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Showing papers in "Journal of Engineering for Gas Turbines and Power-transactions of The Asme in 1997"


Journal ArticleDOI
TL;DR: In this article, the authors present an in-depth study of blade vibration problems that seriously impact development of advanced gas turbine configurations, and they conclude that structural integrity of power plants is the dominant factor that influences the quality, reliability, and marketability of the product.
Abstract: This paper presents an in-depth study of blade vibration problems that seriously impact development of advanced gas turbine configurations. The motivation for this study arises from the author's conviction that structural integrity of power plants is the dominant factor that influences the quality, reliability, and marketability of the product. Implications of this study in the context of potential R&D challenges and opportunities of interest to industry, governments, and academia are discussed.

313 citations


Journal ArticleDOI
TL;DR: In this article, an investigation was conducted to explore the endothermic potential of practical fuels, with inexpensive and readily available catalysts, under operating conditions simulative of high-speed flight applications.
Abstract: Storable hydrocarbon fuels that undergo endothermic reaction provide an attractive heat sink for future high-speed aircraft. An investigation was conducted to explore the endothermic potential of practical fuels, with inexpensive and readily available catalysts, under operating conditions simulative of high-speed flight applications. High heat sink capacities and desirable reaction products have been demonstrated for n-heptane and Norpar 12 fuels using zeolite catalysts in coated-tube reactor configurations. The effects of fuel composition and operating condition on extent of fuel conversion, product composition, and the corresponding endotherm have been examined. The results obtained in this study provide a basis for catalytic-reactor/ heat-exchanger design and analysis.

237 citations


Proceedings ArticleDOI
TL;DR: In this paper, the authors report experimental observations of oscillations produced by a fuel nozzle typical of industrial gas turbines and evaluate how geometric changes to the fuel nozzle will affect the boundary between stable and oscillating combustion.
Abstract: The use of premix combustion in stationary gas turbines can produce very low levels of NO{sub x} emissions. This benefit is widely recognized, but turbine developers routinely encounter problems with combustion oscillations during the testing of new premix combustors. Because of the associated pressure fluctuations, combustion oscillations must be eliminated in a final combustor design. Eliminating these oscillations is often time-consuming and costly because there is no single approach to solve an oscillation problem. Previous investigations of combustion stability have focused on rocket applications, industrial furnaces, and some aeroengine gas turbines. Comparatively little published data is available for premixed combustion at conditions typical of an industrial gas turbine. In this paper, the authors report experimental observations of oscillations produced by a fuel nozzle typical of industrial gas turbines. Tests are conducted in a specially designed combustor capable of providing the acoustic feedback needed to study oscillations. Tests results are presented for pressures up to 10 atmospheres, theoretical considerations, it is expected that oscillations can be characterized by a nozzle reference velocity, with operating pressure playing a smaller role. This expectation is compared to observed data that shows both the benefits and limitations of characterizing the combustor oscillating behavior in termsmore » of a reference velocity rather than other engine operating parameters. This approach to characterizing oscillations is then used to evaluate how geometric changes to the fuel nozzle will affect the boundary between stable and oscillating combustion.« less

127 citations


Journal ArticleDOI
TL;DR: In this paper, an experiment was conducted to evaluate the potential for reduced exhaust emissions and improved efficiency, by way of lean-burn engine fueling with hydrogen supplemented natural gas (Hythane).
Abstract: An experiment was conducted to evaluate the potential for reduced exhaust emissions and improved efficiency, by way of lean-burn engine fueling with hydrogen supplemented natural gas (Hythane). The emissions and efficiency of the Hythane fuel (15% hydrogen, 85% natural gas by volume), were compared to the emissions and efficiency of pure natural gas using a turbocharged, spark ignition, 3.1 L, V-6 engine. The feasibility of heavy duty engine fueling with Hythane was assessed through testing conducted at engine speed and load combinations typical of heavy-duty engine operation. Comparison of the efficiency and emissions at MBT spark timing revealed that Hythane fueling of the test engine resulted in consistently lower brake specific energy consumption and emissions of total hydrocarbons (THC), carbon monoxide (CO), and carbon dioxide (CO{sub 2}), at a given equivalence ratio. There was no clear trend with respect to MBT oxides of nitrogen (NO{sub x}) emissions. It was also discovered that an improved NO{sub x}-THC tradeoff resulted when Hythane was used to fuel the test engine. Consequently, Hythane engine operating parameters can be adjusted to achieve a concurrent reduction in NO{sub x} and THC emissions relative to natural gas fueling.

94 citations


Journal ArticleDOI
TL;DR: In this paper, a two-control-volume model is employed for honeycomb-stator/smooth-rotor seals, with a conventional control-volume used for the throughflow and a capacitance-accumulator model for the honeycomb cells.
Abstract: A two-control-volume model is employed for honeycomb-stator/smooth-rotor seals, with a conventional control-volume used for the throughflow and a capacitance-accumulator model for the honeycomb cells. The control volume for the honeycomb cells is shown to cause a dramatic reduction in the effective acoustic velocity of the main flow, dropping the lowest acoustic frequency into the frequency range of interest for rotordynamics. In these circumstances, the impedance functions for the seals cannot be modeled with conventional (frequency-independent) stiffness, damping, and mass coefficients. More general transform functions are required to account for the reaction forces, and the transfer functions calculated here are a lead-lag term for the direct force function and a lag term for the cross-coupled function. Experimental measurements verify the magnitude and phase trends of the proposed transfer functions. These first-order functions are simple, compared to transfer functions for magnetic bearings or foundations. For synchronous response due to imbalance, they can be approximated by running-speed-dependent stiffness and damping coefficients in conventional rotordynamics codes. Correct predictions for stability and transient response will require more general algorithms, presumably using a state-space format.

91 citations


Journal ArticleDOI
TL;DR: In this paper, a reduced order approach is introduced to predict the steady-state response of mistuned bladed disks, based on a finite element analysis of a tuned system and a computationally efficient mistuned model with a reduced number of degrees of freedom.
Abstract: A reduced order approach is introduced in this paper that can be used to predict the steady-state response of mistuned bladed disks. This approach takes results directly from a finite element analysis of a tuned system and, based on the assumption of rigid blade base motion, constructs a computationally efficient mistuned model with a reduced number of degrees of freedom. Based on a comparison of results predicted by different approaches, it is concluded that: the reduced order model displays structural fidelity comparable to that of a finite element model of the entire bladed disk system with significantly improved computational efficiency; and under certain circumstances both the finite element model and the reduced order model predict quite different response from simple spring-mass models.

82 citations


Journal ArticleDOI
TL;DR: In this paper, NASA-supported experimental and computational results on the mixing of a row of jets with a confined subsonic crossflow in a cylindrical duct were summarized.
Abstract: This paper summarizes NASA-supported experimental and computational results on the mixing of a row of jets with a confined subsonic crossflow in a cylindrical duct. The studies from which these results were excerpted investigated flow and geometric variations typical of the complex three-dimensional flowfield in the combustion chambers in gas turbine engines. The principal observations were that the momentum-flux ratio and the number of orifices were significant variables. Jet penetration was critical, and jet penetration decreased as either the number of orifices increased or the momentum-flux ratio decreased. It also appeared that jet penetration remained similar with variations in orifice size, shape, spacing, and momentum-flux ratio when the number of orifices was proportional to the square root of the momentum-flux ratio. In the cylindrical geometry, planar variances are very sensitive to events in the near-wall region, so planar averages must be considered in context with the distributions. The mass-flow ratios and orifices investigated were often very large (mass-flow ratio >1 and ratio of orifice area-to-mainstream cross-sectional area up to 0.5), and the axial planes of interest were sometimes near the orifice trailing edge. Three-dimensional flow was a key part of efficient mixing and was observed for all configurations. The results shown also seem to indicate that nonreacting dimensionless scalar profiles can emulate the reacting flow equivalence ratio distribution reasonably well. The results cited suggest that further study may not necessarily lead to a universal “rule of thumb” for mixer design for lowest emissions, because optimization will likely require an assessment for a specific application.

82 citations


Journal ArticleDOI
TL;DR: In this paper, the benefits of wave rotor topping in small (300- to 500-kW [400- to 700hp] class) and intermediate (2000- to 3000-kw [3000- to 4000-hp]) turboshaft engines, and large (350- to 450-kN [80,000- to 100,000lb f ] class) high-bypass-ratio turbofan engines are evaluated.
Abstract: The benefits of wave rotor topping in small (300- to 500-kW [400- to 700-hp] class) and intermediate (2000- to 3000-kW [3000- to 4000-hp] class) turboshaft engines, and large (350- to 450-kN [80,000- to 100,000-lb f ] class) high-bypass-ratio turbofan engines are evaluated. Wave rotor performance levels are calculated using a one-dimensional design/analysis code. Baseline and wave-rotor-enhanced engine performance levels are obtained from a cycle deck in which the wave rotor is represented as a burner with pressure gain. Wave rotor topping is shown to enhance the specific fuel consumption and specific power of small- and intermediate-sized turboshaft engines significantly. The specific fuel consumption of the wave-rotor-enhanced large turbofan engine can be reduced while it operates at a significantly reduced turbine inlet temperature. The wave-rotor-enhanced engine is shown to behave off-design like a conventional engine. Discussion concerning the impact of the wave rotor/gas turbine engine integration identifies technical challenges.

78 citations


Journal ArticleDOI
TL;DR: In this paper, the structural eigenvalue problem was formulated as a normalized modal eigen value problem, and it was shown that the amount of interaction in two modes can be simply characterized by six normalized modality parameters and the difference between the normalized frequencies.
Abstract: Modal interaction refers to the way that the modes of a structure interact when its geometry and material properties are perturbed. The amount of interaction between the neighboring modes depends on the closeness of the natural frequencies, the mode shapes, and the magnitude and distribution of the perturbation. By formulating the structural eigenvalue problem as a normalized modal eigenvalue problem, it is shown that the amount of interaction in two modes can be simply characterized by six normalized modal parameters and the difference between the normalized frequencies. In this paper, the statistical behaviors of the normalized frequencies and modes are investigated based on a perturbation analysis. The results are independently verified by Monte Carlo simulations.

70 citations


Journal ArticleDOI
TL;DR: In this paper, the authors demonstrate the capability of an original modular simulator tool for the thermoeconomic analysis of thermal energy systems, which is based on the Thermoeconomic Functional Analysis (T.F.A.).
Abstract: The aim of this work is to demonstrate the capability of an original modular simulator tool for the thermoeconomic analysis of thermal-energy systems. The approach employed is based on the Thermoeconomic Functional Analysis (T.F.A.), which, through definition of the functional productive diagram and the establishment of the capital cost function of each component, allows the marginal costs and the unit product costs, i.e., the internal economy, of the functional exergy flows to be obtained in correspondence to the optimum point. The optimum design of the system is obtained utilizing a traditional optimization technique, which includes both physical structure of the energy system described in terms ofthermodynamic variables and cost model (capital cost of the components, maintenance and amortization factors, unit fuel cost, unit electricity cost, etc.). As an application example to show the practicability of the tool, the thermoeconomic analysis of various complex multipressure combined cycles (with or without steam reheating) is carried out. The results are analyzed and discussed in depth.

67 citations


Journal ArticleDOI
TL;DR: The efficiency and advantages of the intelligent diagnostic procedure in precisely monitoring and quantifying the fault development are systematically brought out considering this bearing system.
Abstract: The objective of this paper is the development of an efficient intelligent diagnostic procedure that considers several diagnostic indices for the quantification of developing faults and for monitoring machine condition. In this procedure, the condition monitoring is performed based on the on-line vibration measurements, and further, the fault quantification is formulated into a multivariate trend analysis. Self-organizing neural networks are then deployed to perform the multivariable trending of the fault development. The attributes for the disordering of “knots” in the trend analysis are determined. The disordering of neural network units is then eliminated by suitably altering the self-organizing neural network algorithm. Applications of this diagnostic procedure to the condition monitoring and life estimation of a bearing system are fully developed and demonstrated. The efficiency and advantages of the intelligent diagnostic procedure in precisely monitoring and quantifying the fault development are systematically brought out considering this bearing system.

Journal ArticleDOI
TL;DR: In this article, internal combustion wave rotors are envisioned for use as pressure gain combustors in gas turbine engines, and a simulation methodology is described, including a presentation of the assumed governing equations for the flow and reaction in the channels, the numerical integration method used, and the modeling of external components such as recirculation ducts.
Abstract: Wave rotor cycles that utilize premixed combustion processes within the passages are examined numerically using a one-dimensional CFD-based simulation. Internal-combustion wave rotors are envisioned for use as pressure-gain combustors in gas turbine engines. The simulation methodology is described, including a presentation of the assumed governing equations for the flow and reaction in the channels, the numerical integration method used, and the modeling of external components such as recirculation ducts. A number of cycle simulations are then presented that illustrate both turbulent-deflagration and detonation modes of combustion. Estimates of performance and rotor wall temperatures for the various cycles are made, and the advantages and disadvantages of each are discussed.

Journal ArticleDOI
TL;DR: In this article, the authors assessed the scales at which commercial, first-generation biomass integrated-gasifier/gas turbine combined cycle (BIG/GTCC) technology is likely to be most economic when fueled by plantation-derived biomass.
Abstract: This paper assesses the scales at which commercial, first-generation biomass integrated-gasifier/gas turbine combined cycle (BIG/GTCC) technology is likely to be most economic when fueled by plantation-derived biomass. First-generation BIG/GTCC systems are likely to be commercially offered by vendors beginning around 2000 and will be based on either pressurized or atmospheric-pressure gasification. Both plant configurations are considered here, with estimates of capital and operating costs drawn from published and other sources. Prospective costs of a farm-grown energy crop (switchgrass) delivered to a power plant are developed with the aid of a geographic information system (GIS) for agricultural regions in the North Central and Southeast US in the year 2000 and 2020. A simplified approach is applied to estimate the cost of delivering chipped eucalyptus from an existing plantation in Northeast Brazil. The optimum capacity (MW{sub opt}), defined as that which yields the minimum calculated cost of electricity (COE{sub m}), varies by geographic region due to differences in delivered biomass costs. With pressurized BIG/GTCC plants, MW{sup opt} is in the range of 230--320 MW{sub e} for the sites considered, assuming most of the land around the power plant is farmed for energy crop production. For atmospheric-pressure BIG/GTCC plants, MW{sub opt} ranges frommore » 110 to 142 MW{sub e}. When a lower fraction of the land around a plant is used for energy farming, values for MW{sub opt} are smaller than these. In all cases, the cost of electricity is relatively insensitive to plant capacity over a wide range around MW{sub opt}.« less

Journal ArticleDOI
TL;DR: In this paper, a variable normal load friction force model is proposed to investigate the influence of shroud-like contact kinematics on the forced response of frictionally constrained turbine blades, and analytical criteria are formulated to predict the transitions between stick, slip, and separation of the interface so as to assess the induced friction forces.
Abstract: Designers of aircraft engines frequently employ shrouds in turbine design. In this paper, a variable normal load friction force model is proposed to investigate the influence of shroudlike contact kinematics on the forced response of frictionally constrained turbine blades. Analytical criteria are formulated to predict the transitions between stick, slip, and separation of the interface so as to assess the induced friction forces. When considering cyclic loading, the induced friction forces are combined with the variable normal load so as to determine the effective stiffness and damping of the friction joint over a cycle of motion. The harmonic balance method is then used to impose the effective stiffness and damping of the friction joint on the linear structure. The solution procedure for the nonlinear response of two-degree-of-freedom oscillator is demonstrated. As an application, this procedure is used to study the coupling effect of two constrained forces, friction force and variable normal load, on the optimization of the shroud contact design.

Journal ArticleDOI
TL;DR: In this article, a novel perturbation technique is introduced for the determination of the forced vibration response of mistuned bladed disks, which is adaptive in the sense that the level of approximation can be varied at will to accommodate any specificities of the tuned system and/or of existing mistuning.
Abstract: In this paper, a novel perturbation technique is introduced for the determination of the forced vibration response of mistuned bladed disks. The proposed technique is adaptive in the sense that the level of approximation can be varied at will to accommodate any specificities of the tuned system and/or of the existing mistuning. This versatility of the proposed approach not only guarantees the reliability of the computed response but also leads to an excellent compromise between accuracy and computational effort. Numerical results are presented that demonstrate both the reliability of the computed response and the computational saving obtained by relying on the suggested perturbation technique as opposed to a straightforward steady-state analysis.

Journal ArticleDOI
TL;DR: In this article, the effect of the rates of species conversion from reactants to products in the combustion model was investigated, and a multiple-time-scale combustion model is formulated to allow consideration of multiple characteristic time scales for the major chemical species.
Abstract: Numerical simulations of direct injection (DI) heavy-duty diesel engine combustion over the entire engine operating range were conducted using the KIVA code, with modifications to the spray, combustion, turbulence, and heat transfer models. In this work, the effect of the rates of species conversion from reactants to products in the combustion model was investigated, and a characteristic-time combustion model was formulated to allow consideration of multiple characteristic time scales for the major chemical species. In addition, the effect of engine operating conditions on the model formulation was assessed, and correlations were introduced into the combustion model to account for the effects of residual gas and Exhaust Gas Recirculation (EGR). The predictions were compared with extensive engine test data. The calculation results had good overall agreement with the experimental cylinder pressure and heat release results, and the multiple-time-scale combustion model is shown to give improved emissions predictions compared to a previous single-time-scale model. Overall, the NO{sub x} predictions are in good agreement with the experiments. The soot predictions are also in reasonable agreement with the measured particulates at medium and high loads. However, at light loads, the agreement deteriorates, possibly due to the neglect of the contribution of SOF in themore » soot model predictions.« less

Journal ArticleDOI
TL;DR: In this paper, a two-dimensional (θ, z) Navier-Stokes solver for multiport wave rotor flow simulation is described, where finite-volume forms of the unsteady thin-layer Navier Stokes equations are integrated in time on multiblock grids that represent the stationary inlet and outlet ports and the moving rotor passages of the wave rotor.
Abstract: A two-dimensional (θ, z) Navier-Stokes solver for multiport wave rotor flow simulation is described. The finite-volume forms of the unsteady thin-layer Navier- Stokes equations are integrated in time on multiblock grids that represent the stationary inlet and outlet ports and the moving rotor passages of the wave rotor. Computed results are compared with three-port wave rotor experimental data. The model is applied to predict the performance of a planned four-port wave rotor experiment. Two-dimensional flow features that reduce machine performance and influence rotor blade and duct wall thermal loads are identified.

Journal ArticleDOI
TL;DR: In this paper, a two-phase laminar counterflow configuration exhibits a green premixed flame, a blue diffusion flame, and a vaporization plane, all three are flat and parallel.
Abstract: Staged combustion can be employed to reduce the formation of CO and NO{sub x}, stabilize the flame, decrease the flame temperature, and create better working conditions in gas turbine combustors. To help understand influences of partial premixing and addition of water on NO{sub x} formation, the authors study two-stage flames in a counterflow spray burner. This paper reports experimental and theoretical results concerning two-stage combustion in which one feed stream is composed of a fuel-rich mixture of methane and air and the other is air. Water sprays are added to the air stream. This two-phase laminar counterflow configuration exhibits a green premixed flame, a blue diffusion flame, and a vaporization plane. All three are flat and parallel. The separation distances between them decrease with increasing equivalence ratio and strain rate. Flow visualization is provided through illumination by an argon ion laser sheet, velocity fields and spray structure are measured by a phase-doppler particle analyzer, concentration fields of major stable species are measured by gas chromatography of samples withdrawn from the flame, and temperature fields are measured by a thermocouple. Numerical integrations that employ a recent chemical-kinetic data base are performed to model the flame structure and NO{sub x} formation. Comparisonsmore » of experimental results with numerical predictions are made to test agreement. This work provides information on hydrocarbon combustion in both premixed flames and diffusion flames, indicates how NO{sub x} is formed in fuel-rich flames, and suggests how the pollutants can be reduced.« less

Journal ArticleDOI
TL;DR: In this paper, a network approach is developed that divides the flow into a number of independent semi-empirical subflows and solves the continuity equation and a pressure drop/flow rate relationship.
Abstract: The preliminary design process of a gas turbine combustor often involves the use of cumbersome, geometry restrictive semi-empirical models. The objective of this analysis is the development of a versatile design tool for gas turbine combustors, able to model all conceivable combustor types. A network approach is developed that divides the flow into a number of independent semi-empirical subflows. A pressure-correction methodology solves the continuity equation and a pressure-drop/flow rate relationship. The development of a full conjugate heat transfer model allows the calculation of flame tube heat loss in the presence of cooling films, annulus heat addition, and flame tube feature heat pick-up. A constrained equilibrium calculation, incorporating mixing and recirculation models, simulates combustion processes. Comparison of airflow results to a well-validated combustor design code showed close agreement. The versatility of the network solver is illustrated with comparisons to experimental data from a reverse flow combustor.

Journal ArticleDOI
TL;DR: In this article, a promising cooling technology for the vanes using steam was developed and the blades were cooled by air, adopting the impingement cooling, film cooling, and so on.
Abstract: It is very essential to raise the thermal efficiency of combined cycle plants from the viewpoint of energy saving and environmental protection. Tohoku Electric Power Co., Inc., and Toshiba Corporation in Japan have jointly studied the next generation of combined cycle systems using 1500°C class gas turbine. A promising cooling technology for the vanes using steam was developed. The blades are cooled by air, adopting the impingement cooling, film cooling, and so on. The cooling effectiveness was confirmed both for the vanes and the blades using a hot wind tunnel. This paper describes the design features of the vanes and the blades, and the results of the verification tests using the hot wind tunnel.

Journal ArticleDOI
TL;DR: In this article, an experimental investigation of a nonreacting multiple jet mixing with a confined crossflow has been conducted, where the jets were perpendicularly injected out of one opposed row of circular orifices into a heated crossflow.
Abstract: An experimental investigation of a nonreacting multiple jet mixing with a confined crossflow has been conducted. Flow and geometric conditions were varied in order to examine favorable parameters for mixing. The requirement for a rapid and intense mixing process originates from combustion applications, especially the RQL-combustion concept. Thus, the jets were perpendicularly injected out of one opposed row of circular orifices into a heated crossflow in a rectangular duct. Spacing and hole size were varied within the ranges referring to combustor applications. The results presented are restricted to an in-line orientation of opposed jet axis. Temperature distribution, mixing rate, and standard deviation were determined at discrete downstream locations. Best, i.e., uniform mixing can be observed strongly depending on momentum flux ratio. For all geometries investigated, an optimum momentum flux ratio yields to a homogeneous temperature distribution in the flow field downstream of the injection plane. Overly high ratios deteriorate the mixing process due to the mutual impact of the opposed entraining jets along with a thermal stratification of the flowfield.

Journal ArticleDOI
TL;DR: In this article, a fracture mechanics approach has been used to predict crack propagation lives in gas turbine engine blades subjected to vibratory high cycle fatigue (HCF), with one blade subjected to only the nonresonant mode and another blade to both modes.
Abstract: A novel fracture mechanics approach has been used to predict crack propagation lives in gas turbine engine blades subjected to vibratory high cycle fatigue (HCF). The vibratory loading included both a resonant mode and a nonresonant mode, with one blade subjected to only the nonresonant mode and another blade to both modes. A life prediction algorithm was utilized to predict HCF propagation lives for each case. The life prediction system incorporates a boundary integral element (BIE) derived hybrid stress intensity solution, which accounts for the transition from a surface crack to corner crack to edge crack. It also includes a derivation of threshold crack length from threshold stress intensity factors to give crack size limits for no propagation. The stress intensity solution was calibrated for crack aspect ratios measured directly from the fracture surfaces. The model demonstrates the ability to correlate predicted missions to failure with values deduced from fractographic analysis. This analysis helps to validate the use of fracture mechanics approaches for assessing damage tolerance in gas turbine engine components subjected to combined steady and vibratory stresses.

Journal ArticleDOI
TL;DR: In this article, active control of a subscale, atmospheric pressure nozzle/combustor arrangement was used to mitigate the effects of combustion instability in afterburner and dump combustor applications, and cyclic injection of small quantities of control fuel was proposed to counteract the periodic heat release that contributes to undesired pressure oscillations.
Abstract: A number of recent articles have demonstrated the use of active control to mitigate the effects of combustion instability in afterburner and dump combustor applications. In these applications, cyclic injection of small quantities of control fuel has been proposed to counteract the periodic heat release that contributes to undesired pressure oscillations. This same technique may also be useful to mitigate oscillations in gas turbine combustors, especially in test rig combustors characterized by acoustic modes that do not exist in the final engine configuration. To address this issue, the present paper reports on active control of a subscale, atmospheric pressure nozzle/combustor arrangement. The fuel is natural gas. Cyclic injection of 14% control fuel in a premix fuel nozzle is shown to reduce oscillating pressure amplitude by a factor of 0.30 (i.e., {approximately}10 dB) at 300 Hz. Measurement of the oscillating heat release is also reported.

Journal ArticleDOI
TL;DR: In this article, the authors proposed an anchored computational combustion dynamics (CCD) model for turbopropulsion engine combustion, which is anchored with one of the modern turboprocess engine combustors.
Abstract: Correlations based on design database, combined with multidimensional computational combustion dynamics (CCD) models are used in the combustion design process. However, because of limitations in the current turbulent combustion models, numerics, and boundary conditions, CCD has provided mainly qualitative trends for aerothermal performance, emissions, and liner wall temperature levels and gradients. To overcome these deficiencies, hybrid modeling approaches have been proposed to analyze existing combustors. A typical hybrid modeling approach combines empirical and semianalytical correlations with CCD to give quantitatively accurate predictions of No x , CO, HC, smoke, lean blowout, ignition, pattern factor, and liner wall temperatures. An alternate approach, anchored CCD, is described in this paper. First, the models were anchored with one of the five modern turbopropulsion engine combustors. The anchored models were then run for the other four combustors. The predicted results correlated well with measured NO x , CO, HC, LBO, and exit temperature quality data, demonstrating a broader applicability of the anchored method. The models were also used for designing a new combustion concept. The pretest prediction agreed well with sector rig data from development hardware, showing the feasibility of using the anchored methodology as a design tool.

Journal ArticleDOI
TL;DR: In this article, basic integration principles and next-generation concepts based on advanced high pressure ratio gas turbines, Humid Air Turbine (HAT) cycles and integration of compression heat and refrigeration sources from the ASU are reviewed and control measures are described for the safe, efficient and reliable operation of these facilities.
Abstract: The commercialization of Integrated Gasification Combined Cycle (IGCC) power has been aided by concepts involving the integration of a cryogenic air separation unit (ASU) with the gas turbine combined-cycle module. Other processes, such as coal-based ironmaking and combined power/industrial gas production facilities, can also benefit from the integration. It is known and now widely accepted that an ASU designed for elevated pressure service and optimally integrated with the gas turbine can increase overall IGCC power output, increase overall efficiency, and decrease the net cost of power generation when compared to nonintegrated facilities employing low-pressure ASUs. The specific gas turbine, gasification technology, NO x emission specification, and other site specific factors determine the optimal degree of compressed air and nitrogen stream integration. Continuing advancements in both air separation and gas turbine technologies offer new integration opportunities to improve performance and reduce costs. This paper reviews basic integration principles and describes next-generation concepts based on advanced high pressure ratio gas turbines, Humid Air Turbine (HAT) cycles and integration of compression heat and refrigeration sources from the ASU. Operability issues associated with integration are reviewed and control measures are described for the safe, efficient, and reliable operation of these facilities.

Journal ArticleDOI
TL;DR: In this paper, the performance analysis of a semiclosed-cycle gas turbine is described, where the working fluid is carbon dioxide and the fuel is low heating value gas synthesized from coal.
Abstract: This paper describes the performance analysis of a semiclosed-cycle gas turbine. The working fluid is carbon dioxide and the fuel is low heating value gas synthesized from coal. The objective of the machine is to produce clean electricity with the smallest efficiency penalty. First, the thermodynamic properties of the gases in the cycle were obtained as a function of temperature and pressure. Then two performance simulation codes were developed. These have the ability of simulating different configurations of open, closed, and semiclosed cycles. The first code was used for cycle optimization and the second for off-design studies. The design and off-design performances of the machine are predicted. The production of clean electricity will be at the expense of a lower efficiency compared with current equipment. Finally, some critical issues for the development of such a gas turbine are identified.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the development of a TC measurement system, based on the capacitive measurement principle, which was undertaken to satisfy the application requirements of a specific class of gas turbine engines.
Abstract: It is an established fact that the efficiency of a gas turbine engine has an inverse relationship with the clearance between the rotor blades and the casing (Tip Clearance, or TC). TC is an essential measurement during the testing of development engines. While commercial TC measurement systems are available, their applicability to an engine is dictated by engine size, geometry, physical accessibility, and temperature distribution around the measurement region. This paper describes the development of a TC measurement system, based on the capacitive measurement principle, which was undertaken to satisfy the application requirements of a specific class of gas turbine engines. The requirements included a relatively long and flexible cable to route the electrical signals out of the engine. The TC measurement system was successfully used during engine testing and valuable data were obtained.

Journal ArticleDOI
TL;DR: In this paper, the authors analyzed the dynamic response of a cracked horizontal rotor and found that the crack causes backward whirl, the amplitude of which increases with the crack size, and the influence of the crack on the synchronous response can be regarded as an additional unbalance whereupon, depending on the speed and the crack location, the response amplitude differs from that of the uncracked rotor.
Abstract: By considering time-dependent terms as external excitation forces, the approximate dynamic response of a cracked horizontal rotor is analyzed theoretically and numerically. The solution is good for small cracks and small vibrations in the stable operating range. For each steady-state harmonic component, the forward and backward whirl amplitudes, the shape and orientation of the elliptic orbit, and the amplitude and phase of the response signals are analyzed, taking into account the effect of crack size, crack location, rotor speed, and unbalance. It is found that the crack causes backward whirl, the amplitude of which increases with the crack. For a cracked rotor, the response orbit for each harmonic component is an ellipse, the shape and orientation of which depend on the crack size. The influence of the crack on the synchronous response of the system can be regarded as an additional unbalance whereupon, depending on the speed and the crack location, the response amplitude differs from that of the uncracked rotor. The nonsynchronous response provides evidence of crack in the subcritical range, but is too small to be detected in the supercritical range. Possibilities for crack detection over the full-speed range include the additional average (the constant) response component, the backward whirl of the response, the ellipticity of the orbit, the angle between the major axis and the vertical axis, and the phase angle difference between vertical and horizontal vibration signals.

Journal ArticleDOI
TL;DR: In this paper, the design and operation of a test combustor suitable for studying combustion oscillations caused by a commercial-scale gas turbine fuel nozzle is discussed, along with initial operating experience and preliminary data that suggests the importance of nozzle reference velocity and air temperature.
Abstract: This paper discusses the design and operation of a test combustor suitable for studying combustion oscillations caused by a commercial-scale gas turbine fuel nozzle. Aside from the need to be conducted at elevated pressures and temperatures, it is desirable for the experimental device to be flexible in its geometry so as to provide an acoustic environment representative of the commercial device. The combustor design, capabilities, and relevant instrumentation for such a device are presented, along with initial operating experience and preliminary data that suggests the importance of nozzle reference velocity and air temperature.

Journal ArticleDOI
TL;DR: This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing interacting with auxiliary bearings during a critical operating condition to develop a better understanding of the dynamic behavior of a magnetic bearing supported rotor system.
Abstract: This study examines the response of a flexible rotor supported by load sharing between linear bearings and an auxiliary clearance bearing. The objective of the work is to develop a better understanding of the dynamical behavior of a magnetic bearing supported rotor system interacting with auxiliary bearings during a critical operating condition. Of particular interest is the effect of coupling between the bearing/housing and shaft vibration on the rotordynamical responses. A simulation model is developed and a number of studies are performed for various parametric configurations. An experimental investigation is also conducted to compare and verify the rotordynamic behavior predicted by the simulation studies. A strategy for reducing synchronous shaft vibration through appropriate design of coupled shaft/bearing/housing vibration modes is identified. The results are presented and discussed.