Showing papers in "Journal of Engineering for Gas Turbines and Power-transactions of The Asme in 1993"
TL;DR: The results of a series of tests designed to determine the melting and subsequent deposition behavior of volcanic ash cloud materials in modern gas turbine engine combustors and high pressure turbine vanes were reported in this article.
Abstract: This paper reports the results of a series of tests designed to determine the melting and subsequent deposition behavior of volcanic ash cloud materials in modern gas turbine engine combustors and high pressure turbine vanes. The specific materials tested were Mt. St. Helens ash and a soil blend containing volcanic ash (black scoria) from Twin Mountain, New Mexico. Hot section test systems were built using actual engine combustors, fuel nozzles, ignitors, and high pressure turbine vanes from an Allison T56 engine can-type combustor and a more modern Pratt and Whitney F-100 engine annular-type combustor. A rather large turbine inlet temperature range can be achieved using these two combustors. The deposition behavior of volcanic materials as well as some of the parameters that govern whether or not these volcanic ash materials melt and subsequently deposit are discussed.Copyright © 1992 by ASME
190 citations
TL;DR: In this paper, an emission model that simulates the combustor by a number of reactors representing various combustion zones is proposed, which addresses the combined effects of spray evaporation and mixing in the reaction zone.
Abstract: To meet the future goals of reduced emissions produced by gas turbine combustors, a better understanding of the process of formation of various pollutants is required. Both empirical and analytical approaches are used to provide the exhaust concentrations of pollutants of interest such as NOx , CO, and unburned hydrocarbon with varying degrees of success. In the present investigation, an emission model that simulates the combustor by a number of reactors representing various combustion zones is proposed. A detailed chemical kinetic scheme was used to provide a fundamental basis for the derivation of a number of expressions that simulate the reaction scheme. The model addresses the combined effects of spray evaporation and mixing in the reaction zone. The model validation included the utilization of a large data base obtained for an annular combustor of a modern turbopropulsion engine. In addition to the satisfactory agreement with the measurements, the model provided insight into the regions within the combustor that could be responsible for the excessive formation of emissions. Methods to reduce the emissions may be implemented in light of such information.
158 citations
TL;DR: In this article, a laminar-and-turbulent characteristic-time combustion model was extended to allow predictions of ignition and combustion in diesel engines, and a more accurate prediction of ignition delay was achieved by using a multistep chemical kinetics model.
Abstract: Ignition and combustion mechanisms in diesel engines were studied using the KIVA code, with modifications to the combustion, heat transfer, crevice flow, and spray models. A laminar-and-turbulent characteristic-time combustion model that has been used successfully for spark-ignited engine studies was extended to allow predictions of ignition and combustion in diesel engines. A more accurate prediction of ignition delay was achieved by using a multistep chemical kinetics model. The Shell knock model was implemented for this purpose and was found to be capable of predicting successfully the autoignition of homogeneous mixtures in a rapid compression machine and diesel spray ignition under engine conditions. The physical significance of the model parameters is discussed and the sensitivity of results to the model constants is assessed. The ignition kinetics model was also applied to simulate the ignition process in a Cummins diesel engine. The post-ignition combustion was simulated using both a single-step Arrhenius kinetics model and also the characteristic-time model to account for the energy release during the mixing-controlled combustion phase. The present model differs from that used in earlier multidimensional computations of diesel ignition in that it also includes state-of-the-art turbulence and spray atomization models. In addition, in this study the model predictionsmore » are compared to engine data. It is found that good levels of agreement with the experimental data are obtained using the multistep chemical kinetics model for diesel ignition modeling. However, further study is needed of the effects of turbulent mixing on post-ignition combustion.« less
139 citations
TL;DR: In this paper, a HBM procedure with a multiterm approximation is proposed to study the nonlinear vibration of a frictionally damped blade with a friction damper, and the results show that the steady-state response and other related behavior of a FDM can be predicted accurately and quickly by an HBM with a multi-term approximation.
Abstract: The friction damper has been widely used to reduce the resonant vibration of blades. The most commonly used methods for studying the dynamic behavior of a blade with a friction damper are direct integration methods. Although the harmonic balance method (HBM) is a well-known method for studying nonlinear vibration problems, generally only a one-term approximation has been proposed to study the nonlinear vibration of a frictionally damped blade. In this work, a HMB procedure with a multiterm approximation is proposed. The results show that the steady-state response and other related behavior of a frictionally damped blade can be predicted accurately and quickly by an HBM with a multiterm approximation.
87 citations
TL;DR: In this paper, a relatively simple theory is presented that can be used to model the flow and pressure distribution in a brush seal matrix, assuming laminar, compressible, isothermal flow and requiring knowledge of an empirical constant: the seal porosity value.
Abstract: A relatively simple theory is presented that can be used to model the flow and pressure distribution in a brush seal matrix. The model assumes laminar, compressible, isothermal flow and requires knowledge of an empirical constant: the seal porosity value. Measurements of the mass flow rate together with radial and axial distributions of pressure were taken on a nonrotating experimental rig. These were obtained using a 122 mm bore brush seal with 0.25 mm radial interference. The experimental data are used to estimate the seal porosity. Measurements of the pressure distributions along the backing ring and under the bristle tips and discussed. Predicted mass flows are compared with those actually measured and there is reasonable agreement considering the limitations of the model.
67 citations
TL;DR: In this paper, an elevated temperature, rotating test rig was designed and built to test labyrinth and brush seals in simulated subsonic and supersonic engine conditions, and the effect of various brush seal parameters, including: initial interference, backplate gap, and multiple brush seal in series.
Abstract: Brush seals are potential replacements for air-to-air labyrinth seals in gas turbine engines. An investigation has been conducted to determine the performance characteristics of brush seals for application in limited-life gas turbine engines. An elevated temperature, rotating test rig was designed and built to test labyrinth and brush seals in simulated subsonic and supersonic engine conditions. Results from initial tests for subsonic applications demonstrated that brush seals exhibit appreciably lower leakage compared to labyrinth seals, and thus offer significant engine performance improvements. Performance results have been obtained showing the effect of various brush seal parameters, including: initial interference, backplate gap, and multiple brush seals in series.
46 citations
TL;DR: In this paper, a single pass heat exchanger test rig with a fuel capacity of 189 liters was developed to evaluate jet fuel thermal stability. This test rig is capable of supplying jet fuel to a 2.15 mm i.d. tube at a pressure up to 3.45 MPa, fuel temperature up to 900 K, and a fuel-tube Reynolds number in the range 300-11,000.
Abstract: A flowing, single-pass heat exchanger test rig, with a fuel capacity of 189 liters, has been developed to evaluate jet fuel thermal stability. This “Phoenix Rig” is capable of supplying jet fuel to a 2.15 mm i.d. tube at a pressure up to 3.45 MPa, fuel temperature up to 900 K, and a fuel-tube Reynolds number in the range 300–11,000. Using this test rig, fuel thermal stability (carbon deposition rate), dissolved oxygen consumption, and methane production were measured for three baseline jet fuels and three fuels blended with additives. Such measurement were performed under oxygen-saturation or oxygen-starved conditions. Tests with all of the blended fuel samples showed a noticeable improvement in fuel thermal stability. Both block temperature and test duration increased the total carbon deposits in a nonlinear fashion. Interestingly, those fuels that need a higher threshold temperature to force the consumption of oxygen exhibited greater carbon deposits than those that consume oxygen at a lower temperature. These observations suggested a complicated relationship between the formation of carbon deposits and the temperature-driven consumption of oxygen. A simple analysis, based on a bimolecular reaction rate, correctly accounted for the shape of the oxygen consumption curve for various fuels. This analysis yielded estimates of global bulk parameters of oxygen consumption. The test rig yielded quantitative results, which will be very useful in evaluating fuels additives, understanding the chemistry of deposit formation, and eventually developing a global chemistry model.
45 citations
TL;DR: In this paper, a procedure has been developed and documented for determining the methane number of gaseous fuels, which provides an indication of the knock tendency of the fuel, and an experimental test matrix was designed for quantifying the effects of ethane, propane, butane, and CO.
Abstract: A procedure has been developed and documented for determining the methane number of gaseous fuels. The methane number provides an indication of the knock tendency of the fuel. An experimental test matrix was designed for quantifying the effects of ethane, propane, butane, and CO[sub 2]. A unique gas mixing and control system was developed to supply test gases to the engine and to control the equivalence ratio and engine operation. The results of the experiments agreed well with the limited data published in the literature. Predictive equations were developed for the methane number (MN) of gaseous fuels using the gas composition. The forms of these equations are suitable for incorporation in a computer program or a spread-sheet.
44 citations
TL;DR: In this paper, the leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied and the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied.
Abstract: The leakage performance of a brush seal with gaseous working fluids at static and low rotor speed conditions was studied. The leakage results are included for air, helium, and carbon dioxide at several bristle/rotor interferences. Also, the effects of packing a lubricant into the bristles and also of reversing the pressure drop across the seal were studied. Results were compared to that of an annular seal at similar operating conditions. In order to generalize the results, they were correlated using corresponding state theory. The brush seal tested had a bore diameter of 3.792 cm (1.4930 in), a fence height of 0.0635 cm (0.025 in), and 1800 bristles/cm circumference (4500 bristles/in circumference). Various bristle/rotor radial interferences were achieved by using a tapered rotor. The brush seal reduced the leakage in comparison to the annular seal, up to 9.5 times. Reversing the pressure drop across the brush seal produced leakage rates approx. the same as that of the annular seal. Addition of a lubricant reduced the leakage by 2.5 times. The air and carbon dioxide data were successfully correlated using corresponding state theory. However, the helium data followed a different curve than the air and carbon dioxide data.
38 citations
TL;DR: In this paper, the thermal stability characteristics of two liquid hydrocarbon fuels are examined using a single-pass system whereby the fuel under test flows only once through a heated tube which is maintained at constant temperature throughout a test duration of six hours.
Abstract: The thermal stability characteristics of two liquid hydrocarbon fuels are examined using a single-pass system whereby the fuel under test flows only once through a heated tube which is maintained at constant temperature throughout a test duration of six hours. Deposition rates on the tube walls are measured by weighing the tube before and after each test.The experimental data are used to derive empirical equations for predicting the effects on deposition rates of variation in fuel temperature, wall temperature, and Reynolds number. It is found that deposition rates are enhanced by increases in fuel temperature, wall temperature and flow velocity, and by reductions in tube diameter. Pressure has no effect on deposition rates provided it is high enough to prevent fuel boiling.Copyright © 1992 by ASME
33 citations
TL;DR: In this article, the ability of the k-e turbulence model to calculate the flow inside gas turbine combustors was assessed using a cylindrical system of coordinates, hybrid differencing, and a mesh with about 40,000 nodes.
Abstract: The present study assesses the ability of the k-e turbulence model to calculate the flow inside gas turbine combustors. Results of calculations using a cylindrical system of coordinates, hybrid differencing, and a mesh with about 40,000 nodes are compared with velocity measurements of the flow inside a perspex model of can-type gas turbine combustor. The larger discrepancies between measurements and predictions were found in the primary region. The complexity of the flow near the primary jet impingement led to underprediction of the maximum negative axial velocity and turbulence kinetic energy by about 35 and 20 percent, respectively. The calculated results exhibited higher levels of momentum diffusion compared to the experiments and did not show the two contrarotating vortices created between the primary jets; no qualitative agreement with the azimuthal velocity downstream of the primary jets could be achieved. Despite these deficiencies, the model gave acceptable results in other regions of the combustor and correct prediction of the main features of the combustor flow was possible.
TL;DR: In this article, a high-speed video camera associated with an image processing unit was used to study the liquid sheet instabilities and disintegration frequency of a gas turbine combustor.
Abstract: Liquid sheet break-up in coflowing shear flow is the mean by which liquids are atomized in practical injectors for gas turbine combustors. The present study explores experimentally the mechanisms of liquid sheet instabilities and spray formation. Experiments are conducted on four airblast geometries. A high-speed video camera associated with an image processing unit was used to study the liquid sheet instabilities. A microphone and a frequency analyzer were used to track the disintegration frequency. Instability amplitude and disintegration length of the liquid sheet were measured. A two-component Phase Doppler Particle Analyzer was used to characterize the resultant spray. The spatial distribution of the particle size is influenced by the swirling flow field. These experimental results will be used to assess models of fuel sheet instabilities and disintegration.
TL;DR: In this article, nonlinear regression estimators for the three-Weibull distribution were used to extract parameters from sintered silicon nitride failure data and a reliability analysis was performed on a turbopump blade.
Abstract: Described here are nonlinear regression estimators for the three-Weibull distribution. Issues relating to the bias and invariance associated with these estimators are examined numerically using Monte Carlo simulation methods. The estimators were used to extract parameters from sintered silicon nitride failure data. A reliability analysis was performed on a turbopump blade utilizing the three-parameter Weibull distribution and the estimates from the sintered silicon nitride data.
TL;DR: In this paper, a 3×-scale model with co-axial, counter-swirling air streams and a production gas turbine combustor swirl cup is characterized at atmospheric pressure.
Abstract: A production gas turbine combustor swirl cup and a 3×- scale model (both featuring co-axial, counter-swirling air streams) are characterized at atmospheric pressure. Such a study provides an opportunity to assess the effect of scale on the behaviour of the continuous phase (gas in the presence of spray) and droplets by comparing the continuous phase velocity, droplet size, and droplet velocity at geometrically analogous positions. Spatially resolved velocity measurements of the continuous phase, droplet size, and droplet velocity were acquired downstream of the production and 3×-scale swirl cups by using two-component phase-Doppler interferometry in the absence of reaction. While the continuous phase flow fields scale well at the exit of the swirl cup, the similarity deviates at downstream locations due to (1) differences in entrainment, and (2) a flow asymmetry in the case of the production hardware. The droplet velocities scale reasonably well with notable exceptions. More significant The droplet velocities scale reasonably well with notable exceptions. More significant differences are noted in droplet size, although the presence of the swirl cup assemblies substantially reduces the differences in size that are otherwise produced by the two atomizers when operated independent of the swirl cup.
TL;DR: In this paper, an efficient multi-objective optimization algorithm was developed to minimize the total weight of the shaft and the transmitted forces at the bearings under the constraints of critical speed constraints.
Abstract: An efficient optimal algorithm is developed to minimize, individually or simultaneously, the total weight of the shaft and the transmitted forces at the bearings. These factors play very important roles in designing a rotor-bearing system under the constraints of critical speeds. The cross-sectional area of the shaft, the bearing stiffness, and the positions of bearings and disks are chosen as the design variables. The dynamic characteristics are determined by applying the generalized polynomial expansion method and the sensitivity analysis is also investigated. For multi-objective optimization, the weighting method (WM), the goal programming method (GPM), and the fuzzy method (FM) are applied. The results show that the present multi-objective optimization algorithm can greatly reduce both the weight of the shaft and the forces at the bearings with critical speed constraints.
TL;DR: In this paper, the generalized polynomial expansion method (GPEM) was applied to both linear and nonlinear rotor systems to determine critical speeds and modes and the unbalance response of rotor bearing systems.
Abstract: The determination of critical speeds and modes and the unbalance response of rotor-bearing systems is investigated with the application of a technique called the generalized polynomial expansion method (GPEM). This method can be applied to both linear and nonlinear rotor systems; however, only linear systems are addressed in this paper. Three examples including single spool and dual rotor systems are used to demonstrate the efficiency and the accuracy of the method. The results indicate a very good agreement between the present method and the finite element method (FEM). In addition, computing time will be saved using this method in comparison with the finite element method.
TL;DR: In this article, the analysis and design of rotor bearing systems with gyroscopic effects are discussed, where the original problem of this nonproportionally damped mechanism is transformed into the state space form so that the transformed problem is similar to the eigenvalue problem for an undamped system.
Abstract: The analysis and design of rotor-bearing systems with gyroscopic effects are discussed in this paper. The original problem of this nonproportionally damped mechanism is transformed into the state space form so that the transformed problem is similar to the eigenvalue problem for an undamped system. It can be easily solved by widely available eigensolvers and the eigenvalue sensitivities needed for the design optimization can also be obtained conveniently using the transformed form. The sequential linear programming technique is employed to solve the design optimization problem. The easy implementation of this proposed approach with a general purpose finite element program is shown in the solution algorithm.
TL;DR: In this paper, the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing were investigated.
Abstract: The role played by fluid forces in determining the rotordynamic stability of a centrifugal pump is gaining increasing attention. The present research investigates the contributions to the rotordynamic forces from the discharge-to-suction leakage flows between the front shroud of the rotating impeller and the stationary pump casing. In particular, the dependency of the rotordynamic characteristics of leakage flows on the swirl at the inlet to the leakage path was examined. An inlet guide vane was designed for the experiment so that swirl could be introduced at the leakage flow inlet. The data demonstrate substantial rotordynamic effects and a destabilizing tangential force for small positive whirl ratios; this force decreased with increasing flow rate. The effect of swirl on the rotordynamic forces was found to be destabilizing.
TL;DR: In this paper, an emission model that combines the analytical capabilities of three-dimensional combustor performance codes with mathematical expressions based on detailed chemical kinetic scheme is formulated to calculate the emissions produced by several engine combustors that varied significantly in design and concept, and operated on both conventional and high-density fuels.
Abstract: An emission model that combines the analytical capabilities of three-dimensional combustor performance codes with mathematical expressions based on detailed chemical kinetic scheme is formulated. The expressions provide the trends of formation and/or the consumption of Nox , CO, and UHC in various regions of the combustor utilizing the details of the flow and combustion characteristics given by the three-dimensional analysis. By this means, the optimization of the combustor design to minimize pollutant formation and maintain satisfactory stability and performance could be achieved. The developed model was used to calculate the emissions produced by several engine combustors that varied significantly in design and concept, and operated on both conventional and high-density fuels. The calculated emissions agreed well with the measurements. The model also provided insight into the regions in the combustor where excessive emissions were formed, and helped to understand the influence of the combustor details and air admissions arrangement on reaction rates and pollutant concentrations.
TL;DR: In this paper, measurements of circumferential liquid distribution are carried out over ranges of injection pressure from 0.34 to 1.72 MPa (50 to 250 psi) using five different simplex nozzles to achieve variations in the discharge orifice length/diameter ratio.
Abstract: Measurements of circumferential liquid distribution are carried out over ranges of injection pressure from 0.34 to 1.72 MPa (50 to 250 psi) using five different simplex nozzles to achieve variations in the discharge orifice length/diameter ratio from 0.5 to 4.0. Two additional simplex nozzles of the same flow number are also examined in order to ascertain the effect of variations in the number of swirl chamber feed slots on circumferential liquid distribution. Mixtures of water and glycerine are used to provide a twelve to one variation in liquid viscosity. The results obtained show that spray uniformity improves markedly at higher injection pressures. Increase in liquid viscosity also has a beneficial effect on spray uniformity. The most uniform circumferential liquid distributions are obtained with nozzles having a discharge orifice length/diameter ratio of between 1 1/2 and 2.
TL;DR: In this paper, a design chart for the reduction of oxides of nitrogen (NOx ) in conventional combustors is presented, which is used to reconfigure the stoichiometry distribution of the combustor of a production engine so as to reduce NOx while holding the emissions of carbon monoxide, unburned hydrocarbons and smoke well below existing regulations.
Abstract: Measurements of the emissions from an experimental engine were analyzed to construct a design chart for the reduction of oxides of nitrogen (NOx ) in conventional combustors. The design chart was used to reconfigure the stoichiometry distribution of the combustor of a production engine so as to reduce NOx while holding the emissions of carbon monoxide, unburned hydrocarbons, and smoke well below existing regulations. Combustion section pressure loss and combustor outlet temperature distributions were substantially unchanged. The modified design was refined with the aid of computational fluid dynamics calculations to optimize the emissions reduction. Worthwhile reductions in NOx were obtained with combustor modifications that are transparent to the engine user.
TL;DR: In this article, a reliability analysis is presented associated with the initiation of matrix cracking in laminated ceramic matrix composite (CMC) materials and a parameter estimation procedure is presented, which allows three parameters to be calculated from a failure population that has an underlying Weibull distribution.
Abstract: For laminated ceramic matrix composite (CMC) materials to realize their full potential in aerospace applications, design methods and protocols are a necessity. The time independent failure response of these materials is focussed on and a reliability analysis is presented associated with the initiation of matrix cracking. A public domain computer algorithm is highlighted that was coupled with the laminate analysis of a finite element code and which serves as a design aid to analyze structural components made from laminated CMC materials. Issues relevant to the effect of the size of the component are discussed, and a parameter estimation procedure is presented. The estimation procedure allows three parameters to be calculated from a failure population that has an underlying Weibull distribution.
TL;DR: In this paper, the split-sleeve cold expansion process has been used successfully for over 20 years to extend the fatigue life of holes in aircraft structures and to enhance engine low-cycle fatigue performance in both production and repair applications.
Abstract: The split-sleeve cold expansion process has been used successfully for over 20 years to extend the fatigue life of holes in aircraft structures. Cold expansion technology can also be applied to enhance engine low-cycle fatigue (LCF) performance in both production and repair applications. Specific test data are presented showing that fatigue life extension can be attained by cold expansion of holes in a wide range of situations (including non-round hole geometries and low edge margins), and in components subjected to high operating temperatures. A cold expanded bushing system is compared to standard shrink- fit bushing installations. Finally, two case studies are used to illustrate the application of cold expansion to full-scale engine components.
TL;DR: In this paper, the effects of back-pressure on flame holding in a gaseous fuel research combustor were investigated, and it was concluded that exit blockage exerts its influence through effects on the jet and recirculation zone shear layers.
Abstract: Experimental information is presented on the effects of back-pressure on flame-holding in a gaseous fuel research combustor. Data for wall temperatures and static pressures are used to infer behavior of the major recirculation zones, as a supplement to some velocity and temperature profile measurements using LDV and CARS systems. Observations of flame behavior are also included. Lean blowout is improved by exit blockage, with strongest sensitivity at high combustor loadings. It is concluded that exit blockage exerts its influence through effects on the jet and recirculation zone shear layers.Copyright © 1992 by ASME
TL;DR: In this article, the feasibility of using abrasive-waterjets (AWJ) for the precision drilling of small-diameter holes in advanced aircraft engine components was investigated, and the results indicated the accuracy and repeatability of the AWJ technique in meeting the air flow and hole size requirements.
Abstract: This paper addresses an experimental investigation on the feasibility of using abrasive-waterjets (AWJs) for the precision drilling of small-diameter holes in advanced aircraft engine components. These components are sprayed with ceramic thermal barrier coating (TBC), and the required holes are typically 0.025 in. in diameter with a drilling angle of 25 deg. The parameters of the AWJ were varied to study their effects on both quantitative and qualitative hole drilling parameters. The unique techniques of assisting the abrasive feed process, ramping the waterjet pressure during drilling, and varying the jet dwell time after piercing were effectively implemented to control hole quality and size. The results of the experiments indicate the accuracy and repeatability of the AWJ technique in meeting the air flow and hole size requirements. Production parts were drilled for prototype engine testing.
TL;DR: A program to establish the potential for introducing fiber reinforced ceramic matrix composites (FRCMC) in future rocket engine turbopumps was instituted in 1987 as mentioned in this paper, and a brief summary of the overall program (both contract and in-house research) is presented.
Abstract: A program to establish the potential for introducing fiber reinforced ceramic matrix composites (FRCMC) in future rocket engine turbopumps was instituted in 1987. A brief summary of the overall program (both contract and in-house research) is presented. Tests at NASA Lewis include thermal upshocks in a hydrogen/oxygen test rig capable of generating heating rates up to 2500 C/sec. Post thermal upshock exposure evaluation includes the measurement of residual strength and failure analysis. Test results for monolithic ceramics and several FRCMC are presented. Hydrogen compatibility was assessed by isothermal exposure of monolithic ceramics in high temperature gaseous hydrogen plus water vapor.
TL;DR: In this article, a linear quadratic regulator-based least square output feedback control (LQ-OPC) procedure is proposed for rotor systems. But the LQ regulator is not suitable for the case of linear asymmetric rotor systems, and it cannot be applied to the complex mode model.
Abstract: The complex mode and balanced realization methods are used separately to obtain reduced-order models for general linear asymmetric rotor systems. The methods are outlined and then applied to a typical rotor system represented by a 52 degree-offreedom finite element model. The accuracy of the two methods is compared for this model and the complex model method is found to be more accurate than the balanced realization method for the desired frequency bandwidth and for models of the same reduced order. However, with some limitations, it is also shown that the balanced realization method can be applied to the reduced-order complex mode model to obtain further order reduction without loss of model accuracy. A “Linear-Quadratic-Regulator-based least-squares output feedback control” procedure is developed for the vibration control of rotor systems. This output feedback procedure eliminates the requirement of an observer for the use of an LQ regulator, and provides the advantage that the rotor vibration can be effectively controlled by monitoring only one single location along the rotor shaft while maintaining an acceptable performance. The procedures presented are quite general and may be applied to a large class of vibration problems including rotordynamics.
TL;DR: In this article, a GT11N gas turbine was retrofitted with ABB's new EV-Silo-Combustor, and the results of extensive field measurements were obtained.
Abstract: In February 1991, a type GT11N gas turbine (Midland, USA) was retrofitted with ABB’s new EV-Silo-Combustor. Tests were then carried out to examine the operation concept, to demonstrate the technical reliability, and to confirm the low emission performance of this new technology. This paper will describe: the combustor design—one single silo combustor mounted on the turbine and equipped with 37 Ev burners; and the results of the extensive field measurements—the operation concept (lean premix combustion without any pilot diffusion flames, 7 burner groups) is simple and reliable. The emission targets—NOx <25 ppmv (15 percent O2 , natural gas), CO<8 ppmv, UHC<5 ppmv—were reached. NOx values are even lower than 15 ppmv at base load. The NOx predictions for the GT11N-EV, based on the results of high-pressure tests in Cologne (ASME Paper No. 90-GT-308), compared very well with the results of field measurements.
TL;DR: In this article, the results of carbonyl compounds and polycyclic aromatic hydrocarbons (PAH) emissions analysis for a heavy-duty Otto cycle engine fueled with natural gas were presented.
Abstract: Previous works carried out in Istituto Motori laboratories have shown that natural gas is a suitable fuel for general means of transportation. This is because of its favorable effects on engine performance and pollutant emissions. The natural gas fueled engine provided the same performance as the diesel engine, met R49 emission standards, and showed very low smoke levels. On the other hand, it is well known that internal combustion engines emit some components that are harmful for human health, such as carbonyl compounds and polycyclic aromatic hydrocarbons (PAH). This paper shows the results of carbonyl compounds and PAH emissions analysis for a heavy-duty Otto cycle engine fueled with natural gas. The engine was tested using the R49 cycle that is used to measure the regulated emissions. The test analysis has been compared with an analysis of a diesel engine, tested under the same conditions. Total PAH emissions from the CNG engine were about three orders of magnitude lower than from the diesel engine. Formaldehyde emission from the CNG engine was about ten times as much as from the diesel engine, while emissions of other carbonyl compounds were comparable.