Flow Field Coupling Between Compression System Components in Asymmetric Flow

1978 ◽  
Vol 100 (1) ◽  
pp. 66-72 ◽  
Author(s):  
E. M. Greitzer ◽  
R. S. Mazzawy ◽  
D. A. Fulkerson
Keyword(s):  
Total Pressure ◽  
Axial Compressor ◽  
Nonuniform Flow ◽  
Asymmetric Flow ◽  
Flow Distortion ◽  
Compression System ◽  
Field Coupling ◽  
Inlet Distortion ◽  
System Components ◽  
Good Agreement

The coupling between an axial compressor in an inlet distortion and downstream compression system components is studied analytically and experimentally. The analysis is based on a nonlinear multisegment parallel compressor model coupled to a calculation procedure for the asymmetric flowfield downstream of the compressor. It is shown that in the presence of circumferentially nonuniform flow (distortion) there can be a strong interaction between the compressor and its overall environment. The response of the compressor to an inlet total pressure distortion can therefore depend not only on the compressor, as has sometimes been assumed, but also on the other components in the compression system. Further, the alteration in the response as a result of the interaction can be either beneficial or detrimental, depending on the nature of the component. Experiments investigating this coupling have been carried out on a three stage compressor. The experiments, which involved operating the compressor with three quite different downstream components, show clearly the differences that can exist in compressor response to distortion due to the compressor-component coupling. The analytical predictions of these effects are found to be in good agreement with the experimental results.

scholarly journals Experimental Investigation of Inlet Distortion Effect on Performance of a Micro Gas Turbine

2018 ◽  
Vol 140 (9) ◽  
Author(s):  
Alireza Naseri ◽  
Shervin Sammak ◽  
Masoud Boroomand ◽  
Alireza Alihosseini ◽  
Abolghasem M. Tousi
Keyword(s):  
Gas Turbine ◽  
Total Pressure ◽  
Nonuniform Flow ◽  
Inlet Flow ◽  
Micro Gas Turbine ◽  
Inlet Distortion ◽  
Air Jet ◽  
Measuring Devices ◽  
Turbine Performance ◽  
Distortion Effect

An experimental study has been carried out to determine how inlet total-pressure distortion affects the performance of a micro gas turbine. An inlet simulator is designed and developed to produce and measure distortion patterns at the inlet to the gas turbine. An air jet distortion generator (AJDG) is used to produce nonuniform flow patterns and total pressure probes are installed to measure steady-state total-pressure distribution at the inlet. A set of wind tunnel tests have been performed to confirm the fidelity of distortion generator and measuring devices. Tests are carried out with the gas turbine exposed to inlet flow with 60 deg, 120 deg, and 180 deg circumferential distortion patterns with different distortion intensities. The performance of the gas turbine has been measured and compared with that of clean inlet flow case. Results indicate that the gas turbine performance can be affected significantly facing with intense inlet distortions.

Shock Propagation and MPT Noise From a Transonic Rotor in Nonuniform Flow

2012 ◽  
Vol 135 (1) ◽  
Author(s):  
Jeffrey J. Defoe ◽  
Zoltán S. Spakovszky
Keyword(s):  
High Speed ◽  
Acoustic Energy ◽  
Shock Propagation ◽  
Far Field ◽  
Nonuniform Flow ◽  
Mean Flow ◽  
Flow Distortion ◽  
Inlet Distortion ◽  
Circumferential Extent ◽  
Transonic Rotor

One of the major challenges in high-speed fan stages used in compact, embedded propulsion systems is inlet distortion noise. A body-force-based approach for the prediction of multiple-pure-tone (MPT) noise was previously introduced and validated. In this paper, it is employed with the objective of quantifying the effects of nonuniform flow on the generation and propagation of MPT noise. First-of-their-kind back-to-back coupled aero-acoustic computations were carried out using the new approach for conventional and serpentine inlets. Both inlets delivered flow to the same NASA/GE R4 fan rotor at equal corrected mass flow rates. Although the source strength at the fan is increased by 38 dB in sound power level due to the nonuniform inflow, far-field noise for the serpentine inlet duct is increased on average by only 3.1 dBA overall sound pressure level in the forward arc. This is due to the redistribution of acoustic energy to frequencies below 11 times the shaft frequency and the apparent cut-off of tones at higher frequencies including blade-passing tones. The circumferential extent of the inlet swirl distortion at the fan was found to be two blade pitches, or 1/11th of the circumference, suggesting a relationship between the circumferential extent of the inlet distortion and the apparent cut-off frequency perceived in the far field. A first-principles-based model of the generation of shock waves from a transonic rotor in nonuniform flow showed that the effects of nonuniform flow on acoustic wave propagation, which cannot be captured by the simplified model, are more dominant than those of inlet flow distortion on source noise. It demonstrated that nonlinear, coupled aerodynamic and aero-acoustic computations, such as those presented in this paper, are necessary to assess the propagation through nonuniform mean flow. A parametric study of serpentine inlet designs is underway to quantify these propagation effects.

Compressor-Diffuser Interaction with Circumferential Flow Distortion

1976 ◽  
Vol 18 (1) ◽  
pp. 25-38 ◽  
Author(s):  
E. M. Greitzer ◽  
H. R. Griswol
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
Static Pressure ◽  
Axisymmetric Flow ◽  
Axial Compressor ◽  
Effective Area ◽  
Flow Distortion ◽  
Diffuser Flow ◽  
Theoretical Predictions ◽  
Annular Diffuser

An analytical and experimental study of axial compressor-diffuser interaction in circumferentially non-uniform flow is reported. An analysis of non-axisymmetric flow in an annular diffuser is presented, based on an inviscid rotational core flow plus the use of a diffuser effective area ratio to account for boundary layer blockage. The analysis is applied to the prediction of the diffuser flow field associated with the presence of a circumferential total pressure distortion. It is found that large static pressure non-uniformities can exist at the inlet of diffusers that are short compared with their mean circumferences, as is usually the case in turbomachinery applications. The analysis is coupled to an asymmetric compressor flow field prediction to provide a method for calculating the effect of an exit diffuser on compressor performance with distortion. It is shown that the velocity defect seen by the compressor can be substantially increased by the presence of the diffuser. The experiments were directed at assessing the method used to predict the flow in the diffuser. Measurements were carried out of the inlet static pressure distortion associated with a circumferentially non-uniform total pressure distribution. The results are found to be in good agreement with the theoretical predictions.

Propagation of Inlet Flow Distortions through an Axial Compressor Stage

1979 ◽  
Vol 101 (1) ◽  
pp. 116-124 ◽  
Author(s):  
J. Colpin
Keyword(s):  
Total Pressure ◽  
Axial Compressor ◽  
Two Dimensional ◽  
Compressor Stage ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Flow Equations ◽  
Finite Difference Technique ◽  
Original Calculation ◽  
Theory And Experiments

This contribution will present an original calculation method predicting the development of an inlet flow distortion through a compressor stage. A finite difference technique is used to treat the flow equations outside the blade rows. That flow is two-dimensional, compressible and nonviscous. The blade rows are modelized using a quasi actuator disk approach, but include the unsteady transfer terms due to the rotor relative motion in a non uniform inlet flow. A set of experimental data, measured on a one stage axial compressor, submitted to a rectangular inlet total pressure distortion will be discussed and will serve as basis for a comparison between theory and experiments.

The Effect of Inlet Flow Distortion on the Performance of Centrifugal Fans for Utility Applications

2011 ◽  
Author(s):  
Jim Greenzweig ◽  
Ray Henry ◽  
Ted Holm
Keyword(s):  
Total Pressure ◽  
Total Efficiency ◽  
Negative Effects ◽  
Flow Distortion ◽  
Testing Program ◽  
Inlet Distortion ◽  
Maximum Reduction ◽  
Centrifugal Fans ◽  
Pressure Development ◽  
Open Position

This paper provides an overview of published literature on the effect of inlet Flow Distortion on the performance of centrifugal fans, with an emphasis on a recently completed testing program [8] on the effect of inlet distortion on the performance of airfoil bladed Centrifugal fans, at various inlet vane positions. The results of this testing program [8] show that a model fan, when equipped with variable inlet vanes, is generally subject to lower levels of performance degradation, for a given level of inlet distortion, than the same model when the variable inlet vanes are not present. This indicates that the variable inlet vanes are acting to condition the distorted flow prior to entry into the fan wheel in a beneficial manner. The reduction in performance degradation seems to occur when the variable inlet vanes are wide open (parallel to the fan shaft axis), and does not seem to improve with closure of the variable inlet vanes. The maximum reduction in Total Pressure development and Total Efficiency measured for fans without variable inlet vanes in this test was −8.4% and −6.1% respectively. The maximum reduction in Total Pressure development and Total Efficiency measured for fans with variable inlet vanes in the wide open position was reduced to −2.9% and −3.5% respectively. In fact, the beneficial effects of the variable inlet vanes appear to be greater with the vanes in the wide open position, and are possibly less beneficial when the inlet vanes are partially closed. (The maximum reduction in Total Pressure development and Total Efficiency measured for fans with variable inlet vanes in a partially open position was −2.5% and −4.1% respectively.) Refer to Table 2 for a summary of the Maximum Distortion Observed for the testing program. An unanticipated result of the tests conducted [8] is the discovery that the effects of distortion seem to vary with the position of the rating point along the fan curve, with distortion effects being greater at higher flow conditions and lower at lower flow conditions. An actual field case study on the negative effects of inlet distortion on a centrifugal Induced Draft (ID) fan is also presented. Recommended steps to take in designing a fan system to minimize the potential for any negative effects on fan performance from inlet distortion are also presented. The conclusion compares the results of previously conducted tests [1, 2] and recently conducted tests [8], and concludes that the recent tests do not support many of the earlier findings. This leads to authors to believe that the actual impact of inlet distortion is highly dependent on the specific geometry of the airfoil-bladed centrifugal fan involved, and the relationship to various fan design parameters is not currently well understood.

Effect of Inflow Circumferential Distortion on a Transonic Axial Compressor

2017 ◽  
Author(s):  
Yuyun Li ◽  
Zhiheng Wang ◽  
Guang Xi
Keyword(s):  
Total Pressure ◽  
Rotor Blade ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Leading Edge ◽  
Inlet Distortion ◽  
Compressor Rotor ◽  
Structure Changes ◽  
Transonic Axial Compressor

The Inlet distortion, which may lead to the stability reduction or structure failure, is often non-ignorable in an axial compressor. In the paper, the three-dimensional unsteady numerical simulations on the flow in NASA rotor 67 are carried out to investigate the effect of inlet distortion on the performance and flow structure in a transonic axial compressor rotor. A sinusoidal circumferential total pressure distortion with eleven periods per revolution is adopted to study the interaction between the transonic rotor and inlet circumferential distortion. Concerning the computational expense, the flow in two rotor blade passages is calculated. Various intensities of the total pressure distortion are discussed, and the detailed flow structures under different rotating speeds near the peak efficiency condition are analyzed. It is found that the distortion has a positive effect on the flow near the hub. Even though there is no apparent decrease in the rotor efficiency or total pressure ratio, an obvious periodic loading exists over the whole blade. The blade loadings are concentrated in the region near the leading edge of the rotor blade or regions affected by the oscillating shocks near the pressure side. The time averaged location of shock structure changes little with the distortion, and the motion of shocks and the interactions between the shock and the boundary layer make a great contribution to the instability of the blade structure.

Prediction of Inlet Distortion Induced Axial Compressor Flow Field Instability in Mid-Air Refueling

2003 ◽  
Author(s):  
Ningyu Liu ◽  
Eddie Yin-Kwee Ng ◽  
Hong Ngiap Lim ◽  
Tock Lip Tan
Keyword(s):  
Incidence Angle ◽  
Axial Compressor ◽  
Axial Flow ◽  
Flow Distortion ◽  
Practical Applications ◽  
Inlet Distortion ◽  
Compressor Inlet ◽  
Physical Insight ◽  
Flow Compressor ◽  
Compressor Efficiency

The propagation of strong distortion at inlet of an axial compressor is investigated by applying the critical distortion line and the integral method. The practical applications, such as flaming of leakage fuel during mid-air refueling process, are implemented to show the details of the numerical methodology used in analysis of the axial flow compressor behavior and the propagation of inlet distortion. From the viewpoint of compressor efficiency, the propagation of inlet flow distortion is further described by a compressor critical performance and its critical characteristic. The simulated results present a useful physical insight to the significant effects of inlet parameters on the distortion extension, velocity, and compressor characteristics. The distortion level, the size of distortion area, and the incidence angle at compressor inlet, and the rotor blade speed are found to be the major parameters affecting the mass flow rate of engine.

Review—Axial Compressor Stall Phenomena

1980 ◽  
Vol 102 (2) ◽  
pp. 134-151 ◽  
Author(s):  
E. M. Greitzer
Keyword(s):  
Fluid Dynamic ◽  
Axial Compressor ◽  
Rotating Stall ◽  
Empirical Correlations ◽  
Flow Distortion ◽  
Stall Margin ◽  
Compression System ◽  
Casing Treatment ◽  
Linearized Stability ◽  
Compressor Performance

Stall in compressors can be associated with the initiation of several types of fluid dynamic instabilities. These instabilities and the different phenomena, surge and rotating stall, which result from them, are discussed in this paper. Assessment is made of the various methods of predicting the onset of compressor and/or compression system instability, such as empirical correlations, linearized stability analyses, and numerical unsteady flow calculation procedures. Factors which affect the compressor stall point, in particular inlet flow distortion, are reviewed, and the techniques which are used to predict the loss in stall margin due to these factors are described. The influence of rotor casing treatment (grooves) on increasing compressor flow range is examined. Compressor and compression system behavior subsequent to the onset of stall is surveyed, with particular reference to the problem of engine recovery from a stalled condition. The distinction between surge and rotating stall is emphasized because of the very different consequences on recoverability. The structure of the compressor flow field during rotating stall is examined, and the prediction of compressor performance in rotating stall, including stall/unstall hysteresis, is described.

High-Fidelity Numerical Analysis of Per-Rev-Type Inlet Distortion Transfer in Multistage Fans: Part I—Simulations With Selected Blade Rows

2008 ◽  
Author(s):  
Jixian Yao ◽  
Steven E. Gorrell ◽  
Aspi R. Wadia
Keyword(s):  
Total Pressure ◽  
High Performance ◽  
Full Range ◽  
High Fidelity ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Inlet Distortion ◽  
Multi Stage ◽  
Depth Analysis ◽  
Total Temperature

Demands for improved performance and operability of advanced propulsion systems require an understanding of the physics of inlet flow distortion transfer and generation and the subsequent engine response. This also includes developing a high-fidelity characterization capability and suitable tools/rules for the design of distortion tolerant engines. This paper describes efforts to establish a high-fidelity prediction capability of distortion transfer and fan response via high-performance computing. The current CFD capability was evaluated with a focus of predicting the transfer of prescribed inlet flow distortions. Numerical simulations, comparison to experimental data, and analysis of two selected three-stage fans are presented. The unsteady RANS code Pturbo demonstrated remarkable agreement with data, accurately capturing both the magnitude and profile of total pressure and total temperature measurements. Part I of the paper describes the establishment of the required numerical simulation procedures. The computational domains are limited to the first three blade rows for the first multistage fan and the last three blade rows for the second fan. The paper presents initial validation and analysis of the total pressure distortion transfer and the total temperature distortion generation. Based on the established ground work of Part I, the entire two multi-stage fans were simulated with inlet distortion at normal operating condition and near stall condition, which is part II of the paper. Part II presents the full range validation against engine test data, and in-depth analysis of distortion transfer and generation mechanisms through out the two fans.

High-Fidelity Numerical Analysis of Per-Rev-Type Inlet Distortion Transfer in Multistage Fans—Part I: Simulations With Selected Blade Rows

2010 ◽  
Vol 132 (4) ◽  
Author(s):  
Jixian Yao ◽  
Steven E. Gorrell ◽  
Aspi R. Wadia
Keyword(s):  
Total Pressure ◽  
High Performance ◽  
Full Range ◽  
High Fidelity ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Inlet Distortion ◽  
Depth Analysis ◽  
Total Temperature ◽  
Generation Mechanisms

Demands for improved performance and operability of advanced propulsion systems require an understanding of the physics of inlet flow distortion transfer and generation and the subsequent engine response. This also includes developing a high-fidelity characterization capability and suitable tools/rules for the design of distortion tolerant engines. This paper describes efforts to establish a high-fidelity prediction capability of distortion transfer and fan response via high-performance computing. The current CFD capability was evaluated with a focus of predicting the transfer of prescribed inlet flow distortions. Numerical simulations, comparison to experimental data, and analysis of two selected three-stage fans are presented. The unsteady Reynolds-Averaged Navier-Stokes (RANS) code PTURBO demonstrated remarkable agreement with data, accurately capturing both the magnitude and profile of total pressure and total temperature measurements. Part I of this paper describes the establishment of the required numerical simulation procedures. The computational domains are limited to the first three blade rows for the first multistage fan and the last three blade rows for the second fan. This paper presents initial validation and analysis of the total pressure distortion transfer and the total temperature distortion generation. Based on the established ground work of Part I, the entire two multistage fans were simulated with inlet distortion at normal operating condition and near stall condition, which is Part II of this paper. Part II presents the full range validation against engine test data and in-depth analysis of distortion transfer and generation mechanisms throughout the two fans.

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