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Showing papers on "Axial compressor published in 1993"


Journal ArticleDOI
TL;DR: In this article, the formation of finite amplitude rotating stall cells was investigated on two laboratory test compressors and it was shown that modal perturbations are not always present prior to stall, and when present, sometimes have little direct effect on the formation.
Abstract: Studies have been conducted on two laboratory test compressors to investigate the process leading to the formation of finite amplitude rotating stall cells. The measurements were obtained from circumferential arrays of hot wires and were spatially and temporarily analyzed to show that modal perturbations are not always present prior to stall, and when present, sometimes have little direct effect on the formation of the stall cells. The measurements lead to the conclusion that the occurrence of modal perturbations, and the formation of finite amplitude stall cells, are two separate phenomena, both occurring under roughly the same conditions at the peak of the pressure rise characteristic. The measurements also underline the hitherto unsuspected importance of short length scale disturbances in the process of stall inception. Examples are given of different ways in which stall cells can develop and the conclusions are backed up with a summary of current test data from various machines around the world.

381 citations


Journal ArticleDOI
TL;DR: In this paper, the wave pattern in terms of the individual spatial Fourier components was considered and a simple proportional control law was implemented for each harmonic, which yielded an 11 percent decrease in the stalling mass flow, while control of the first, second, and third harmonics together reduced the mass flow by 23 percent.
Abstract: The onset of rotating stall has been delayed in a low-speed, single-stage, axial research compressor using active feedback control. Control was implemented using a circumferential array of hot wires to sense propagating waves of axial velocity upstream of the compressor. Using this information, additional circumferentially traveling waves were then generated with appropriate phase and amplitude by «wiggling» inlet guide vanes driven by individual actuators. The control scheme considered the wave pattern in terms of the individual spatial Fourier components. A simple proportional control law was implemented for each harmonic. Control of the first spatial harmonic yielded an 11 percent decrease in the stalling mass flow, while control of the first, second, and third harmonics together reduced the stalling mass flow by 23 percent

199 citations


Journal ArticleDOI
TL;DR: In this paper, two distinctly different methods were used to delay the onset of rotating stall and surge in a four-stage compressor using fast-acting air injection valves and removing emerging stall cells.
Abstract: This paper reports on an experimental program in which active control was successfully applied to both rotating stall and surge in a multistage compressor. Two distinctly different methods were used to delay the onset of rotating stall in a four-stage compressor using fast-acting air injection valves. The amount of air injected was small compared to the machine mass flow, the maximum being less than 1.0 percent. In some compressor configurations modal perturbations were observed prior to stall. By using the air injection valves to damp out these perturbations, an improvement of about 4.0 percent in stall margin was achieved. The second method of stall suppression was to remove emerging stall cells by injecting air in their immediate vicinity. Doing this repeatedly delayed the onset of stall, giving a stall margin improvement of about 6.0 percent. Further studies were conducted using a large plenum downstream of the compressor to induce the system to surge rather than stall. The resulting surge cycles were all found to be initiated by rotating stall and therefore the stall suppression systems mentioned above could also be used to suppress surge. In addition, it was possible to arrest the cyclical pulsing of a compressor already in surge.

197 citations


Patent
16 Jun 1993
TL;DR: In this paper, a process and a device for monitoring and controlling a compressor by measuring pressure fluctuations within at least one stage of the compressor (10) in the region of the housing (24) by means of a pressure sensing device (32) was presented.
Abstract: A process and a device for monitoring and controlling a compressor (10) by measuring pressure fluctuations within at least one stage of the compressor (10) in the region of the housing (24) of the compressor (10) by means of at least one pressure sensing device (32), deriving a frequency signal which comprises at least one characteristic peak (70) in a region of a characteristic frequency assigned to one of the compressor stages (12, 14) and determining at least one peak parameter indicative of the operational status of the compressor (10), and generating a status change signal in case the peak parameter lies beyond a predetermined value range, which is used for controlling the compressor (10).

104 citations


Journal ArticleDOI
TL;DR: In this paper, a simple model for loss created by the tip clearance flow in axial compressors is presented, based on an experimental program performed in conjunction with the Dawes three-dimensional Navier-Stokes calculation method.
Abstract: A simple model for loss created by the tip clearance flow in axial compressors is presented, based on an experimental program performed in conjunction with the Dawes three-dimensional Navier-Stokes calculation method. The principal mechanism of loss (entropy creation) caused by tip leakage flow has been established to be the mixing of flows of similar speeds but different direction. Calculations show that relative motion of the endwall relative to the tip has a small effect on clearance flow. The simple model correctly predicts the magnitude of tip clearance loss and the trend with changes of tip clearance for the cascade tested. For a given geometry the loss is almost exactly proportional to the ratio of tip clearance to blade span; the loss directly associated with the clearance is smaller than often assumed

90 citations


Journal ArticleDOI
TL;DR: In this paper, the authors make a comparison between high-speed and low-speed compressors and show that high speed compressors are more stable than low speed machines, and that low speed results do not necessarily apply well to high speed machines.
Abstract: By far the greater part of our understanding about stall and surge in axial compressors comes from work on low-speed laboratory machines. As a general rule, these machines do not model the compressibility effects present in high-speed compressors and therefore doubt has always existed about the application of low-speed results to high-speed machines. In recent years interest in active control has led to a number of studies of compressor stability in engine-type compressors. The instrumentation used in these experiments has been sufficiently detailed that, for the first time, adequate data are available to make direct comparisons between high-speed and low-speed compressors

68 citations


Patent
29 Jun 1993
TL;DR: In this article, an axial flow turbomachine is provided having a diffuser that directs the flow of working fluid from a turbine exit to an exhaust housing having a bottom opening, thereby turning the flow 90° from the axial to radial direction.
Abstract: An exhaust system for an axial flow turbomachine is provided having a diffuser that directs the flow of working fluid from a turbine exit to an exhaust housing having a bottom opening, thereby turning the flow 90° from the axial to radial direction In the exhaust housing, the flow exiting at the top of the diffuser turns 180° from the vertically upward direction to the downward direction The strength of the vortex formed in the exhaust housing as a result of this turning is minimized by orienting the outlet of an outer exhaust flow guide portion of the diffuser so that it lies in a plane that makes an angle with a plane perpendicular to the turbine axis As a result, the minimum axial length of the outer flow guide occurs at a location remote from the exhaust housing outlet and the maximum axial length occurs at a location proximate the opening, thereby crowding the vortex against a radially extending baffle in the exhaust housing

60 citations


Patent
12 May 1993
TL;DR: In this article, a method and system for increasing the pressure of gaseous fuel delivered to a fuel system of a gas turbine engine is described, where a portion of pressurized gas or compressed air is discharged from a high-pressure section of the gas turbine and is communicated to a plurality of radial inflow turbines or axial flow turbines.
Abstract: A method and system for increasing the pressure of gaseous fuel delivered to a fuel system of a gas turbine engine. A portion of pressurized gas or compressed air is discharged from a high-pressure section of the gas turbine engine and is communicated to a plurality of radial inflow turbines or axial flow turbines. Energy is transferred from each turbine to a plurality of compressors driven by the turbines. Gaseous fuel is supplied to an inlet of one of the compressors. The compressed gaseous fuel is then cooled downstream of the compressors. The aftercooled and compressed gaseous fuel is delivered to the fuel system of the gas turbine engine.

60 citations


Patent
16 Jun 1993
TL;DR: In this article, a process and a device for monitoring vibrational excitation of an axial compressor by measuring of pressure fluctuation within at least one stage (12, 14) of said compressor (10) in the region of the compressor housing (24) by means of a pressure sensing device (32) are presented.
Abstract: A process and a device for monitoring vibrational excitation of an axial compressor (10) by measuring of pressure fluctuation within at least one stage (12, 14) of said compressor (10) in the region of the compressor housing (24) by means of at least one pressure sensing device (32), checking whether each of said frequency signals comprises at least one excitation peak within a predetermined frequency interval in a region of at least one critical frequency of said compressor (10), determining at least one peak parameter indicative of the excitation status of the compressor (10) and generating a status change signal in case said peak parameter has a value lying beyond a predetermined value range.

58 citations


Proceedings ArticleDOI
24 May 1993
TL;DR: In this article, a three-stage axial research compressor has been actively stabilized by damping low amplitude circumferentially travelling waves which can grow into rotating stall using a circumferential array of hot wire sensors, and an array of high speed individually positioned control vanes as the actuator.
Abstract: A three-stage, low speed axial research compressor has been actively stabilized by damping low amplitude circumferentially travelling waves which can grow into rotating stall. Using a circumferential array of hot wire sensors, and an array of high speed individually positioned control vanes as the actuator, the first and second spatial harmonics of the compressor were stabilized down to a characteristic slope of 0.9, yielding an 8% increase in operating flow range. Stabilization of the third spatial harmonic did not alter the stalling flow coefficient. The actuators were also used open loop to determine the forced response behavior of the compressor. A system identification procedure applied to the forced response data then yielded the compressor transfer function. The Moore-Greitzer, 2-D, stability model was modified as suggested by the measurements to include the effect of blade row time lags on the compressor dynamics. This modified Moore-Greitzer model was then used to predict both the open and closed loop dynamic response of the compressor. The model predictions agreed closely with the experimental results. In particular, the model predicted both the mass flow at stall without control and the design parameters needed by, and the range extension realized from, active control.Copyright © 1993 by ASME

56 citations


Journal ArticleDOI
TL;DR: In this article, a two-color, five-beam LDV system has been configured to make simultaneous three-component velocity measurements of the flow field in a 2-stage axial compressor model.
Abstract: A two-color, five-beam LDV system has been configured to make simultaneous three-component velocity measurements of the flow field in a two-stage axial compressor model. The system has been used to make time-resolved measurements both between compressor blade rows and within the rotating blade passages in an axial compressor. The data show the nature and behavior of the complex, three-dimensional flow phenomena present in the tip region of a compressor as they convect downstream. In particular, the nature of the tip leakage vortex is apparent, being manifested by high blockage as well as the expected vortical motion. The data indicate that the radial flows associated with the tip leakage vortex begin to decrease while within the rotor passage, and that they temporarily increase aft of the passage

Patent
08 Apr 1993
TL;DR: In this paper, a gas turbine engine having improved output horsepower and a method of achieving it is described, where the engine has, in order, a low pressure compressor, a high pressure compressor and a combustor, with a speed reducing gear box there between.
Abstract: A gas turbine engine having improved output horsepower and a method of achieving it. The engine has, in order, a low pressure compressor, a high pressure compressor, a combustor, a high pressure turbine and a low pressure turbine. The high pressure turbine is drivingly connected to both compressors with a speed reducing gear box therebetween. An intercooler between the compressors reduces the horsepower requirement of the high pressure compressor. Flow from the combustor is sufficiently heated to enable the high pressure turbine to drive both compressors with the output horsepower of the low pressure turbine devoted to the engine load.

Journal ArticleDOI
TL;DR: In this paper, the surge and rotating stall post-instability behaviors of axial flow compressors are investigated from a bifurcation-theoretic perspective, using a model and system data presented by Greitzer (1976a).
Abstract: The surge and rotating stall post-instability behaviors of axial flow compressors are investigated from a bifurcation-theoretic perspective, using a model and system data presented by Greitzer (1976a). For this model, a sequence of local and global bifurcations of the nonlinear system dynamics is uncovered. This includes a global bifurcation of a pair of large-amplitude periodic solutions. Resulting from this bifurcation are a stable oscillation (surge) and an unstable oscillation (antisurge). The latter oscillation is found to have a deciding significance regarding the particular post-instability behavior experienced by the compressor. These results are used to reconstruct Greitzer's (1976b) findings regarding the manner in which post-instability behavior depends on system parameters. Although the model does not directly reflect non axisymmetric dynamics, use of a steady-state compressor characteristic approximating the measured characteristic of Greitzer (1976a) is found to result in conclusions that compare well with observation. Thus, the paper gives a convenient and simple explanation of the boundary between surge and rotating stall behaviors, without the use of more intricate models and analyses including non axisymmetric flow dynamics.

Patent
29 Jul 1993
TL;DR: In this paper, a cooling system for an axial flow compressor of a gas turbine engine is described, which includes a cooling device to cool the portion of air tapped from the primary air flow, which cooled air is directed into a cooling air chamber.
Abstract: A cooling system for an axial flow compressor of a gas turbine engine is disclosed having a device to tap a portion of air from the primary air flow flowing through the axial compressor and a control device associated with the tap to control the amount of air tapped from the primary air flow. The system also includes a cooling device to cool the portion of air tapped from the primary air flow, which cooled air is directed into a cooling air chamber. The cooling air chamber is located between the last rotor stage of the compressor and a cone attached to the last stage and extending downstream from the rotor wheel. Nozzles associated with the cooling air chamber direct cooling air from the chamber onto the rotating rotor wheel such that a portion of the cooling air passes into the peripheral groove defined by the rotor wheel between the wheel and the blade root, while another portion of the cooling air from the nozzles is directed onto the surface of the cone in order to cool the blades and the cone.

Patent
16 Jun 1993
TL;DR: In this paper, a process and a device for detecting fouling of an axial compressor by measuring the pressure fluctuations within at least one of the stages (12, 14) of the compressor (10) in the region of a compressor housing (24) by means of a pressure sensing device (32) was presented.
Abstract: A process and a device for detecting fouling of an axial compressor (10) by measuring the pressure fluctuations within at least one of the stages (12, 14) of the compressor (10) in the region of the compressor housing (24) by means of at least one pressure sensing device (32), deriving a frequency signal from the signals delivered from the pressure sensing device (32), checking whether each of the frequency signals comprises at least one characteristic peak (70) in the region of a characteristic frequency assigned to one of the compressor stages (12, 14), and deriving a fouling parameter from the frequency signal which depends on a peak parameter indicative of the form of the characteristic peak (70) and indicating the status of fouling of the compressor.

Patent
02 Aug 1993
TL;DR: A gas turbine engine ducted to have the air pass sequentially through a single stage axial flow compressor, a single-stage hybrid axial-radial centrifugal compressor and a burner, an inward flow radial turbine, an axialflow, high-pressure turbine, and then exit nozzles.
Abstract: A gas turbine engine ducted to have the air pass sequentially through a single stage axial-flow compressor, a single-stage hybrid axial-radial centrifugal compressor, a burner, an inward flow radial turbine, an axial-flow, high-pressure turbine, and then exit nozzles. The axial compressor and axial turbine are on a common core shaft. The centrifugal compressor and the radial turbine are on a common porous hub and form an integral, modular unit in which forces on the radial turbine blades drive the centrifugal compressor. The porous common hub permits air to transpire from the compressor to the turbine, serving to cool the turbine. Fuel is burned in annular, "folded-comma" shaped burners with multiple fuel-injection and ignition zones (two stage combustion). The gas flow path has an outer annular duct, a first inner duct from the burner, and a second inner duct to the burner. The outer duct shares common walls with the first and second inner ducts. The first inner duct is located between the burner and the outer duct. The second inner duct is located between the outer duct and a portion of the turbine section.

Journal ArticleDOI
TL;DR: In this paper, the results of numerical solutions of the Navier-Stokes equations, augmented by the k-ϵ model of turbulence, for an axial flow fan operating under distorted inflow conditions are presented.

Patent
09 Dec 1993
TL;DR: In this article, an aircraft subsystem provides the aircraft with all its electrical and conditioned air requirements without requiring the extraction of either shaft power and/or pressurized air from the aircraft's main engines.
Abstract: An aircraft subsystem provides the aircraft with all its electrical and conditioned air requirements without requiring the extraction of either shaft power and/or pressurized air from the aircraft's main engines. At the core of this subsystem are two rotating assemblies journaled on non-oil lubricated bearings to a housing. One assembly includes a cooling turbine, a starter/generator, a core compressor, and a high pressure stage of a two stage axial turbine, all mounted on a single shaft. A combustor is disposed between the core compressor and the turbine. The other assembly is comprised of the low pressure stage of the axial turbine coupled to a load compressor via a second shaft. The high pressure turbine stage and cooling turbine are sized to drive the core compressor and starter/generator which provides all the aircraft's electrical needs both on the ground and inflight. The low pressure turbine stage drives the load compressor, which produces pressurized air that is conditioned through heat exchange components and then expanded and cooled across the cooling turbine before being delivered to the aircraft cabin.

Journal ArticleDOI
TL;DR: In this article, a detailed aerodynamic study of a transonic, high-throughflow, single-stage compressor is presented, which is comprised of a low-aspect-ratio rotor combined alternately with two different stator designs.
Abstract: A detailed aerodynamic study of a transonic, high-throughflow, single-stage compressor is presented. The compressor stage was comprised of a low-aspect-ratio rotor combined alternately with two different stator designs. Both experimental and numerical studies are conducted to understand the details of the complex flow field present in this stage. Aerodynamic measurements using high-frequency, Kulite pressure transducers and conventional probes are compared with results from a three-dimensional viscous flow analysis. A steady multiple blade row approach is used in the numerical technique to examine the detailed flow structure inside the rotor and the stator passages. The comparisons indicate that many flow field features are correctly captured by viscous flow analysis, and therefore unmeasured phenomena can be studied with some level of confidence.

Journal ArticleDOI
TL;DR: In this paper, numerical solutions of the Reynolds-averaged Navier-Stokes equations are presented for convective heat transfer inside axisymmetric rotating disc cavities and four different mathematical models of turbulence are used.

Journal ArticleDOI
TL;DR: In this paper, the propagation of pressure disturbances due to potentialflow interaction and viscous-wake interaction from upstream blade rows in axial-turbine-blade rotor cascades is investigated.
Abstract: This paper investigates the propagation of pressure disturbances due to potentialflow interaction and viscous-wake interaction from upstream blade rows in axialturbine-blade rotor cascades. Results are obtained by modeling the effects of the upstream stator viscous wake and potential-flow fields as incoming disturbances on the downstream rotor flow field, where the computations areperformed. A computer program is used to calculate the unsteady rotor flow fields. The amplitudes for the rotor inlet distortions due to the two types of interaction are based on a review of available experimental and computational data

Proceedings ArticleDOI
28 Jun 1993
TL;DR: In this paper, the axial structure of the perturbations, as well as the behavior of the least stable eigenmode (which determines stability for the machine), is shown to be similar for the high speed situation and for incompressible flow.
Abstract: Ahstrart A computational and theoretical procedure is described for the analysis of flow instability in high speed, muhistage COInpreSWTS. Specifically, lhe paper presenu the first rigorous analysis of the type of twedirnensianal, long wavelength, small amplitude, compressible flow perturbations which have been experimentally observed to develop into rotating stall. The analysis shows that compressibility has a stabilizing influence for both singlestage and multistage machines. A much more impwtant conclusion, however, is that the axial structure of the perturbations, as well as the behavior of the least stable eigenmode (which determines stability for the machine), is similar for the high speed situation and for incompressible flow. The rotating stall onset behaviors of high speed and low speed machines are therefore predicted to be similar in many respecrs. One key feature of this similarity is &at it is the overall slope of the (futl) compressor pressure rise characteristic, rather than the slope of any single stage, that determines instability onset. Numerical resulb are given to illusbate these points, as well as to show the specific influence of parameters such as blade tip Mach number and compessot length.

Proceedings ArticleDOI
24 May 1993
TL;DR: In this paper, an eight-stage fixed geometry engine compressor was compared with low-speed laboratory data and the results showed remarkable similarities in both the stalling and surging behaviour of the two machines, particularly when the engine compressor is run at intermediate speeds.
Abstract: By far the greater part of our understanding about stall and surge in axial compressors comes from work on low-speed laboratory machines. As a general rule, these machines do not model the compressibility effects present in high-speed compressors and therefore doubt has always existed about the application of low-speed results to high-speed machines. In recent years interest in active control has led to a number of studies of compressor stability in engine type compressors. The instrumentation used in these experiments has been sufficiently detailed that, for the first time, adequate data is available to make direct comparisons between high-speed and low-speed compressors. This paper presents new data from an eight-stage fixed geometry engine compressor and compares this with low-speed laboratory data. The results show remarkable similarities in both the stalling and surging behaviour of the two machines, particularly when the engine compressor is run at intermediate speeds. The engine results also show that, as in the laboratory tests, surge is precipitated by the onset of rotating stall. This is true even at very high speeds where it had previously been thought that surge might be the result of a blast wave moving through the compressor. This paper therefore contains new information about high-speed compressors and confirms that low speed testing is an effective means of obtaining insight into the behaviour of high-speed machines.Copyright © 1993 by ASME

Journal ArticleDOI
TL;DR: In this paper, the thermal effects for a viscous flow in a capillary have been calculated by solving the equation of energy, where a parabolic profile is assumed for the axial flow velocity.
Abstract: The thermal effects for a compressible viscous flow in a capillary have been calculated by solving the equation of energy, where a parabolic profile is assumed for the axial flow velocity. It is shown that, in general, the temperature changes are small (a few millikelvins), consistent with the current assumption of an isothermal flow, except in the case of a critical, i.e., very compressible, fluid where the cooling can be substantial. This effect is demonstrated numerically on the basis of a flow of ethylene in nearly critical circumstances.

Journal ArticleDOI
Fredric Ehrich1
TL;DR: In this article, the authors derived a quantitative estimate of the proportionality factor, which relates the Thomas/Alford force in axial flow compressors (i.e., the tangential force generated by a radial deflection of the rotor) to the torque level in the compressor.
Abstract: It is now widely recognized that destabilizing forces, tending to generate forward rotor whirl, are generated in axial flow turbines as a result of the nonuniform torque induced by the nonuniform tip-clearance in a deflected rotor--the so called Thomas/Alford force. It is also recognized that there will be a similar effect in axial flow compressors, but qualitative considerations cannot definitively establish the magnitude or even the direction of the induced whirling forces--that is, if they will tend to forward or backward whirl. Applying a parallel compressor model to simulate the operation of a compressor rotor deflected radially in its clearance, it is possible to derive a quantitative estimate of the proportionality factor [beta] which relates the Thomas/Alford force in axial flow compressors (i.e., the tangential force generated by a radial deflection of the rotor) to the torque level in the compressor. The analysis makes use of experimental data from the GE Aircraft Engines Low Speed Research Compressor facility comparing the performance of three different axial flow compressors, each with four stages (typical of a mid-block of an aircraft gas turbine compressor) at two different clearances. It is found that the value of [beta] is in the range of +0.27 tomore » [minus]0.71 in the vicinity of the stages' nominal operating line and +0.08 to [minus]1.25 in the vicinity of the stages' operation at peak efficiency. The value of [beta] reaches a level of between [minus]1.16 and [minus]3.36 as the compressor is operated near its stalled condition.« less


Patent
04 Jan 1993
TL;DR: Bleed holes are introduced into a volute tongue of a centrifugal pump or compressor to provide a double acting means of boundary layer control at the volute Tongue as discussed by the authors, which improves the flow range of the pumps and compressors.
Abstract: The present invention is directed to a method and apparatus for improving the flow range in centrifugal pumps and compressors. Bleed holes are introduced into a volute tongue of a centrifugal pump or compressor thereby providing a double acting means of boundary layer control at the volute tongue.

Journal ArticleDOI
TL;DR: In this paper, the authors describe the phenomenon of stall and surge in an axial flow aeroengine using fast response static pressure measurements from the compressor of a Rolls-Royce VIPER engine.
Abstract: This paper describes the phenomenon of stall and surge in an axial flow aeroengine using fast response static pressure measurements from the compressor of a Rolls-Royce VIPER engine. It details the growth of flow instability at various speeds, from a small zone of stalled fluid involving only a few blades into the violent surge motion of the entire machine. Various observations from earlier theoretical and compressor rig results are confirmed by these new engine measurements. The main findings are as follows: (1) The point of stall inception moves rearward as engine speed increases, and is shown to be simply related to the axial matching of the compressor

Proceedings ArticleDOI
01 Jun 1993
TL;DR: In this paper, a three-dimensional analysis for the flow inside a transonic, high-through-flow, single stage compressor is presented, which is based on a numerical method for solving the 3D Navier-Stokes equation for unsteady viscous flow through multiple turbomachinery blade rows.
Abstract: A three-dimensional unsteady, viscous aerodynamic analysis has been developed for the flow inside a transonic, high-through-flow, single stage compressor. The compressor stage is comprised of a low-aspect-ratio rotor and a closely coupled stator. The analysis is based on a numerical method for solving the three-dimensional Navier-Stokes equation for unsteady viscous flow through multiple turbomachinery blade rows. The method solves the fully three-dimensional Navier-Stokes equation with an implicit scheme. A two-equation turbulence model with a low-Reynolds-number modification is applied for the turbulence closure. A third-order accurate upwinding scheme is used to approximate convection terms while a second-order accurate central difference scheme is used for the discretization of the viscous terms. A second-order accurate scheme is employed for the temporal discretization. The numerical method is applied to study the unsteady flow field inside a transonic, high-through-flow, axial compressor stage. The numerical results are compared with available experimental data.

Journal ArticleDOI
TL;DR: A simpler yet reliable design technique is presented that allows this category of ducted axial fan rotors, in the presence of swirl-free inlet flow, to be designed to achieve a specified duty with sufficient accuracy for engineering purposes.