Showing papers in "Journal of Engineering for Power in 1979"
137 citations
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TL;DR: In this article, the authors performed parameter monitoring for hot corrosion control of utility gas turbine alloys with respect to simple aluminides, overlay coatings and precious metal coatings.
Abstract: Hot corrosion is the accelerated rate of oxidation of coatings and substrates, which occurs when a condensed phase is present on the surface. The major constituent of the corrosive deposit is sodium sulfate, although when fuels other than light distillates are employed, the deposit can contain various amounts of vanadium pentaoxide, an impurity present in many heavy distillates and most residual oils. Other corrodents that can be present in varying concentrations are lead, carbon and alkali halides. The coatings employed to extend the life of gas turbine alloys, and the alloys themselves exhibit varying degrees of resistance to hot corrosion. In our study of the “Parameter Monitoring for Corrosion Control of Utility Gas Turbines” we are determining the relative effect of each of the aforementioned corrodents with respect to simple aluminides, overlay coatings and precious metal coatings on three nickel base superalloys and one cobalt base superalloy. Although these studies are being conducted over the temperature range from 1500 to 1800°F, this presentation primarily emphasizes the completed high temperature results with some examples of the ongoing lower temperature studies.
57 citations
TL;DR: In this paper, a mathematical model for three-dimensional, swirling, recirculating, turbulent flows inside can combustors is presented, restricted to single-phase, diffusion-controlled combustion, with negligible radiation heat-transfer.
Abstract: The paper presents a mathematical model for three-dimensional, swirling, recirculating, turbulent flows inside can combustors. The present model is restricted to single-phase, diffusion-controlled combustion, with negligible radiation heat-transfer; however, the introduction of other available physical models can remove these restrictions. The mathematical model comprises differential equations for: continuity, momentum, stagnation enthalpy, concentration, turbulence energy, its dissipation rate, and the mean square of concentration fluctuations. The simultaneous solution of these equations by means of a finite-difference solution algorithm yields the values of the variables at all internal grid nodes. The prediction procedure, composed of the mathematical model and its solution algorithm, is applied to predict the fields of variables within a representative can combustor; the results are compared with corresponding measurements. The predicted results give the same trends as the measured ones, but the quantitative agreement is not always acceptable; this is attributed to the combustion process not being truly diffusion-controlled for the experimental conditions investigated.
53 citations
TL;DR: In this article, the effects of Coriolis force on two-dimensional laminar and turbulent boundary layers were investigated and a numerical evaluation was carried out utilizing the Monin-Oboukhov coefficient including the effect of rotation.
Abstract: To investigate the effects of Coriolis force on two-dimensional laminar and turbulent boundary layers, quantitative experiments were performed. A numerical evaluation was also carried out utilizing the Monin-Oboukhov coefficient including the effect of rotation. From the experimental results, the boundary layer development was found to be promoted on the unstable side and suppressed on the stable side, in comparison with the case of zero-rotation. In the stable boundary layer, the critical Reynolds number for relaminarization was observed to increase as rotation number was decreased. Calculated results were seen to predict the stabilizing effect of Coriolis force fairly well.
49 citations
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40 citations
TL;DR: In this article, the effect of injecting steam generated by exhaust gas waste heat into a gas turbine with 3060°R turbine inlet temperature has been analyzed, and two alternate steam injection cycles are compared with a combined cycle using a conventional steam bottoming cycle.
Abstract: The effect of injecting steam generated by exhaust gas waste heat into a gas turbine with 3060°R turbine inlet temperature has been analyzed. Two alternate steam injection cycles are compared with a combined cycle using a conventional steam bottoming cycle. A range of compression ratios (8, 12, 16, and 20) and water mass injection ratios (0 to 0.4) were analyzed to determine effect on net turbine power output per pound of air and cycle thermodynamic efficiency. A water/fuel cost tradeoff analysis is also provided. The results indicate promising performance and economic advantages of steam injected cycles relative to more conventional utility power cycles. Application to coal-fired configuration is briefly discussed.
38 citations
32 citations
TL;DR: In this paper, a rotating pressure pattern was generated at a much higher mass flow rate than the one leading to surge, and the measured pressure fluctuations should not be attributed to rotating zones of separated boundary layers at the diffuser walls.
Abstract: Pressure fluctuations at various locations on the flow path of two centrifugal compressor stages have been recorded and analyzed in the time and frequency domains. Two distinct types of unsteady phenomena were measured: a rotating pressure pattern in the diffuser and compressor system surge. The rotating pressure pattern was generated at a much higher mass flow rate than the one leading to surge. At the onset of the diffuser instability, the pressure fluctuations were sinusoidal and lines of equal phase were radial. For the tests conducted in the present investigation, two nodal diameters existed in the pattern. Both amplitude and rotational speed of the pressure pattern gradually increased as the mass flow rate was gradually decreased. It is shown that the measured pressure fluctuations should not be attributed to rotating zones of separated boundary layers at the diffuser walls. This does not mean, however, that a stationary separation zone in the diffuser is not necessary to generate the measured diffuser instability.
TL;DR: In this paper, a comprehensive computer aided design procedure and its use to investigate mixed flow turbines for automotive turbocharger applications is described, where the outside dimensions of rotor and casing as well as blade angles are determined from one-dimensional design and off design calculations, the detailed blade shape from quasi-three-dimensional analysis and mechanical stressing and vibration programs, and geometric data are presented as outside views and sections of the rotor by a graphics subroutine.
Abstract: The paper describes a comprehensive computer aided design procedure and its use to investigate mixed flow turbines for automotive turbocharger applications. The outside dimensions of rotor and casing as well as blade angles are determined from one-dimensional design and off design calculations, the detailed blade shape from quasi-three-dimensional analysis and mechanical stressing and vibration programs, and geometric data are presented as outside views and sections of the rotor by a graphics subroutine. The procedure consists of a series of separate programs rather than a single program, so that the designer’s intervention at each stage of the process can be applied. Two mixed flow rotors were designed, manufactured and tested in a specially designed high speed dynamometer. The first was intended to achieve a substantial increase in mass flow over the reference radial rotor without loss of efficiency, while the latter was intended as a direct replacement of the reference radial rotor, but should give more favorable pulse performance when operating in conjunction with an engine due to changes in the operating map viz: a) lower tip speeds for best efficiency, and b) flatter mass flow characteristics. Both effects were predicted by analysis and confirmed by tests.
TL;DR: In this article, the results of testing a fast-acting rotating stall control system on a J-85 turbojet engine under sea level static conditions, both with and without inlet distortion was presented.
Abstract: : This report presents the results of testing a fast-acting rotating stall control system on a J-85 turbojet engine under sea level static conditions, both with and without inlet distortion. The control is an electronic feedback control system which uses unsteady pressure signals produced by pressure sensors within the compressor to detect incipient rotating stall and provide a correction signal when such a condition occurs. On the J-85 engine, the correction signal is used to drive a fast-response hydraulic actuator which operates intermediate stage compressor bleed doors and inlet guide vane flaps. The performance of the stall control was tested by closing the bleed doors until rotating stall occurred or until the control anticipated stall and held the bleed doors open. The tests showed that the control is capable of anticipating stall before it occurs and keeping the engine completely clear of stall at speeds up to 80 percent of design speed. No tests were performed above 80 percent of design because opening the bleed doors at such speeds might aggravate the stall rather than clear it. (Author)
TL;DR: In this article, the authors investigated the leakage loss caused by leaks through the impeller tip clearance for a centrifugal compressor and found that the average compressor performance would be reduced by about 4 percent when the relative clearance was increased from 0.0125 to 0.125 and the resulting leakage loss was dependent on the Reynolds number.
Abstract: Fluid loss caused by leaks through the impeller tip clearance was investigated for a centrifugal compressor. Operating conditions, Reynolds number, and clearance were varied independently during the experiment. It was found that the average compressor performance would be reduced by about 4 percent when the relative clearance was increased from 0.0125 to 0.125 and the resulting leakage loss was dependent on the Reynolds number, the tendency of which was just opposite in case of wall friction loss, as was well-known. Moreover, a determination of the leakage loss coefficient was made as a function of the relative clearance, relative leak level and the Reynolds number as the result of this experiment.
TL;DR: In this article, an analytical formulation which can be applied to obtain unsteady aerodynamic solutions for a cascade of flat plate blades oscillating in sub-sonic or supersonic flow with either sub-sonic or sub-supersonic axial velocity component is presented.
Abstract: An analytical formulation which can be applied to obtain unsteady aerodynamic solutions for a cascade of flat plate blades oscillating in subsonic or supersonic flow with either subsonic or supersonic axial velocity component is presented. In the analysis, the flow is assumed to be two-dimensional and isentropic and the blades are undergoing small amplitude harmonic oscillations. The method of superposition of basic wave solutions of the linearized unsteady flow equation is used to construct the flow field induced by the harmonic motion of blades in cascade. This method leads to an integral equation from which the unsteady loading on a blade can be determined. Since the equation applied to both subsonic and supersonic inlet conditions, the present approach provides a unified basis for analyzing and understanding the complex physical phenomena associated with flow past vibrating cascades. The technique used to determine a solution for an unsteady supersonic cascade is also described and the results obtained are shown to agree with those from previous solution.
TL;DR: In this article, the exhaust gases from five large diesel engines were sampled at three sites over a range of engine operating conditions using fuels with 0.05 to 0.8 percent sulfur, and measurements of SO2, SO3, CO, CO2, H2O, NO, NOX, chlorides, acid dew point, peak rate temperature of acid deposition, particulate loading, particle sizing, particle composition and smoke number were made to characterize the diesel exhaust.
Abstract: The exhaust gases from five large diesel engines--1500 to 6400 kW (2000 to 8900 hp)--were sampled at three sites over a range of engine operating conditions using fuels with 0.05 to 0.8 percent sulfur. Measurements of SO2, SO3, CO, CO2, H2O, NO, NOX, chlorides, acid dew point, peak rate temperature of acid deposition, particulate loading, particle sizing, particulate composition and smoke number were made to characterize the diesel exhaust. Total particulate emissions varied directly with fuel sulfur content. Fifty percent or greater of the total particulate emissions were less than or equal to 0.3 micrometers in size. The fouling and corrosion potential of diesel exhaust gas can be approximated given the fuel analysis and engine operating conditions.
TL;DR: In this paper, a series of experimental tests and computational analyses are reported for two automotive gas turbine diffusers, including an interstage and an exhaust diffuser plus collector, at Reynolds numbers and inlet blockage levels characteristic of engine operating conditions.
Abstract: A series of experimental tests and computational analyses are reported for two automotive gas turbine diffusers. The diffusers include an interstage and an exhaust diffuser plus collector. The diffuser models were tested at Reynolds numbers and inlet blockage levels characteristic of the engine operating conditions. A rig test of the interstage diffuser is also reported. Inlet swirl and Mach number were systematically varied in the model tests. Good recovery was found for each diffuser at zero swirl. Recovery degraded at high swirl for the interstage diffuser. The exhaust diffuser with a double discharge collector showed little sensitivity to inlet swirl. Flow visualization indicates that the interstage diffuser was separated at modest swirl levels, at least in the model test. Pressure recovery in the rig (with upstream rotor and downstream stator) was found to be greater than in the model test (using 'clean' inlet conditions). Comparisons between measured wall pressures and calculations provide further basic insights.
TL;DR: In this article, the authors used state-of-the-art shock tube technology and well-established transient test techniques to measure the spatial distribution of heat transfer rate on the first-stage stationary inlet nozzle of AiResearch Manufacturing Co.'s TFE-731-2 engine under gas-dynamic conditions that simulate engine operating conditions.
Abstract: To achieve maximum cycle efficiencies with gas-turbine engines, designers must select the maximum possible turbine inlet temperatures within the constraints of structural integrity. Because accurate heat-transfer rate measurements are an important consideration in achieving this goal, Calspan Corp. has appllied state-of-the-art shock-tube technology and well-established transient-test techniques to measure the spatial distribution of heat-transfer rate on the first-stage stationary inlet nozzle of AiResearch Manufacturing Co.'s TFE-731-2 engine under gas-dynamic conditions that simulate engine operating conditions. The test time and mass-flow rate available from the shock-tube reservoir and the flow-establishment time in the test section are all acceptable for the purposes of performing these heat-transfer rate measurements. In addition, useful cascade-loss data can be obtained using the experimental apparatus described.
TL;DR: In this paper, the results of a series of measurements made on the fretting wear of heat exchanger tubes and support plates at room temperature in a nitrogen/air atmosphere are presented.
Abstract: The results of a series of measurements made on the fretting wear of heat exchanger tubes and support plates at room temperature in a nitrogen/air atmosphere are presented. The fretting wear is shown to be a function of the amplitude and frequency of tube vibration as well as the gap between the tube and the support plate and the mean load supported by the tube. An empirical model is developed in Part II for predicting the fretting wear.
TL;DR: In this article, an improved and generalized version of the pseudo-random binary noise (PRBN) method is described, which shows significant improvements compared to other methods of dynamic response testing.
Abstract: A knowledge of the dynamic behavior of a gas turbine has always been necessary for control system design and development. One of the chief problems is to measure this information from engine tests as comprehensively and accurately as possible in the minimum amount of time. A technique, based on an improved and generalized version of the pseudo-random binary noise (PRBN) method, is described which shows significant improvements compared to other methods of dynamic response testing. The technique involves the injection of a small PRBN or other random disturbance into the fuel flow or variable geometry actuator, the recording of the response of other engine parameters to that disturbance and the subsequent use of a computer to derive the frequency response. The requirements necessary for successful dynamic response testing are discussed and a comparison made between the improved PRBN technique and conventional sinewave testing from actual engine tests. A number of engines have been analyzed using the new method, some of the results from which are presented.
TL;DR: In this article, the suitability of jet fuels made from oil shale and coal and a data base which will allow optimization of future fuel characteristics, taking energy efficiency of manufacture and the tradeoffs in aircraft and engine design into account.
Abstract: In connection with the anticipated impossibility to provide on a long-term basis liquid fuels derived from petroleum, an investigation has been conducted with the objective to assess the suitability of jet fuels made from oil shale and coal and to develop a data base which will allow optimization of future fuel characteristics, taking energy efficiency of manufacture and the tradeoffs in aircraft and engine design into account. The properties of future aviation fuels are examined and proposed solutions to problems of alternative fuels are discussed. Attention is given to the refining of jet fuel to current specifications, the control of fuel thermal stability, and combustor technology for use of broad specification fuels. The first solution is to continue to develop the necessary technology at the refinery to produce specification jet fuels regardless of the crude source.