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.

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.

scholarly journals JET ENGINE INLET DISTORTION SCREEN AND DESCRIPTOR EVALUATION

2017 ◽  
Vol 57 (1) ◽  
pp. 22-31 ◽  
Author(s):  
Jiří Pečinka ◽  
Gabriel Thomas Bugajski ◽  
Petr Kmoch ◽  
Adolf Jílek
Keyword(s):  
Total Pressure ◽  
Basic Flow ◽  
Interface Plane ◽  
Inlet Channel ◽  
Flow Distortion ◽  
Turbine Engine ◽  
Inlet Distortion ◽  
Mass Flow Rates ◽  
Total Temperature ◽  
The University

Total pressure distortion is one of the three basic flow distortions (total pressure, total temperature and swirl distortion) that might appear at the inlet of a gas turbine engine (GTE) during operation. Different numerical parameters are used for assessing the total pressure distortion intensity and extent. These summary descriptors are based on the distribution of total pressure in the aerodynamic interface plane. There are two descriptors largely spread around the world, however, three or four others are still in use and can be found in current references. The staff at the University of Defence decided to compare the most common descriptors using basic flow distortion patterns in order to select the most appropriate descriptor for future department research. The most common descriptors were identified based on their prevalence in widely accessible publications. The construction and use of these descriptors are reviewed in the paper. Subsequently, they are applied to radial, angular, and combined distortion patterns of different intensities and with varied mass flow rates. The tests were performed on a specially designed test bench using an electrically driven standalone industrial centrifugal compressor, sucking air through the inlet of a TJ100 small turbojet engine. Distortion screens were placed into the inlet channel to create the desired total pressure distortions. Of the three basic distortions, only the total pressure distortion descriptors were evaluated. However, both total and static pressures were collected using a multi probe rotational measurement system.

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 Inlet Flow Distortions in Centrifugal Fans

1984 ◽  
Author(s):  
S. Madhavan ◽  
J. DiRe ◽  
T. Wright
Keyword(s):  
Comprehensive Evaluation ◽  
Performance Degradation ◽  
Centrifugal Fan ◽  
Flow Distortion ◽  
Inlet Flow ◽  
Fan Performance ◽  
Inlet Distortion ◽  
Centrifugal Fans ◽  
Inlet Flow Distortion ◽  
Distortion Parameters

Recent measurements of the performance of a centrifugal fan subjected to inlet flow distortion are presented. Results of axial and multilobed distortion modes are discussed in the context of a previously published study to provide a more comprehensive evaluation of related fan performance degradation. Distortion parameters presented in the previous study are shown to be insufficient for the complete description of inlet distortion and further indicators are proposed.

Assessing the Impact of the Inlet Total Pressure Distortion on the Turbofan Thrust

2018 ◽  
pp. 19-30
Author(s):  
Yu. A. Ezrokhi ◽  
E. A. Khoreva
Keyword(s):  
Total Pressure ◽  
External Compression ◽  
Average Value ◽  
Inlet Distortion ◽  
Air Inlet ◽  
Engine Thrust ◽  
Relative Value ◽  
Main Effect ◽  
Pressure Recovery Factor ◽  
The Impact

The paper considers techniques to develop a mathematical model using a method of «parallel compressors». The model is intended to estimate the impact of the air inlet distortion on the primary parameters of the aero-engine.  The paper presents rated estimation results in the context of twin spool turbofan design for two typical cruiser modes of flight of the supersonic passenger jet. In estimation the base values σbase and the average values of the inlet ram recovery σave remained invariable. Thus, parametrical calculations were performed for each chosen relative value of the area of low-pressure region.The paper shows that an impact degree of the inlet distortion on the engine thrust for two modes under consideration is essentially different. In other words, if in the subsonic mode the impact assessment can be confined only to taking into account the influence of decreasing average values of the inlet total pressure, the use of such an assumption in the supersonic cruiser mode may result in considerable errors.With invariable values of the pressure recovery factor at the engine intake, which correspond to the speed of flight for a typical air inlet of external compression σbase, and average value σave, a parameter Δσuneven  has the main effect on the engine thrust, and degree of this effect essentially depends on a difference between σave and σbase values.

Unsteady Three-Dimensional Analysis of Inlet Distortion in a Transonic Fan

2006 ◽  
Author(s):  
Peng Sun ◽  
Guotal Feng
Keyword(s):  
Shock Wave ◽  
Total Pressure ◽  
Large Scale ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Inlet Distortion ◽  
Flow Loss ◽  
Large Scale Vortex ◽  
Total Temperature ◽  
Transonic Fan

A time-accurate three-dimensional Navier-Stokes solver of the unsteady flow field in a transonic fan was carried out using "Fluent-parallel" in a parallel supercomputer. The numerical simulation focused on a transonic fan with inlet square wave total pressure distortion and the analysis of result consisted of three aspects. The first was about inlet parameters redistribution and outlet total temperature distortion induced by inlet total pressure distortion. The pattern and causation of flow loss caused by pressure distortion in rotor were analyzed secondly. It was found that the influence of distortion was different at different radial positions. In hub area, transportation-loss and mixing-loss were the main loss patterns. Distortion not only complicated them but enhanced them. Especially in stator, inlet total pressure distortion induced large-scale vortex, which produced backflow and increased the loss. While in casing area, distortion changed the format of shock wave and increased the shock loss. Finally, the format of shock wave and the hysteresis of rotor to distortion were analyzed in detail.

Effects of Inlet Distortion on the Flow Field in a Transonic Compressor Rotor

1996 ◽  
Author(s):  
Chunill Hah ◽  
Douglas C. Rabe ◽  
Thomas J. Sullivan ◽  
Aspi R. Wadia
Keyword(s):  
Boundary Layer ◽  
Flow Field ◽  
Viscous Flow ◽  
Total Pressure ◽  
Stokes Equations ◽  
Three Dimensional ◽  
Aerodynamic Loss ◽  
Transonic Compressor ◽  
Inlet Distortion ◽  
Compressor Rotor

The effects of circumferential distortions in inlet total pressure on the flow field in a low-aspect-ratio, high-speed, high-pressure-ratio, transonic compressor rotor are investigated in this paper. The flow field was studied experimentally and numerically with and without inlet total pressure distortion. Total pressure distortion was created by screens mounted upstream from the rotor inlet. Circumferential distortions of 8 periods per revolution were investigated at two different rotor speeds. The unsteady blade surface pressures were measured with miniature pressure transducers mounted in the blade. The flow fields with and without inlet total pressure distortion were analyzed numerically by solving steady and unsteady forms of the Reynolds-averaged Navier-Stokes equations. Steady three-dimensional viscous flow calculations were performed for the flow without inlet distortion while unsteady three-dimensional viscous flow calculations were used for the flow with inlet distortion. For the time-accurate calculation, circumferential and radial variations of the inlet total pressure were used as a time-dependent inflow boundary condition. A second-order implicit scheme was used for the time integration. The experimental measurements and the numerical analysis are highly complementary for this study because of the extreme complexity of the flow field. The current investigation shows that inlet flow distortions travel through the rotor blade passage and are convected into the following stator. At a high rotor speed where the flow is transonic, the passage shock was found to oscillate by as much as 20% of the blade chord, and very strong interactions between the unsteady passage shock and the blade boundary layer were observed. This interaction increases the effective blockage of the passage, resulting in an increased aerodynamic loss and a reduced stall margin. The strong interaction between the passage shock and the blade boundary layer increases the peak aerodynamic loss by about one percent.

scholarly journals Introduction of an Universal Scale-Up Method for the Efficiency of Axial and Centrifugal Fans

2014 ◽  
Author(s):  
Peter F. Pelz ◽  
Stefan S. Stonjek
Keyword(s):  
Test Data ◽  
Scale Up ◽  
Pressure Rise ◽  
Flow Coefficient ◽  
Total Efficiency ◽  
Scaling Method ◽  
Centrifugal Fans ◽  
Axial Fans ◽  
Definition Of ◽  
Acceptance Tests

Acceptance tests on large fans to prove the performance (efficiency and total pressure rise) to the customer are expensive and sometimes even impossible to perform. Hence there is a need for the manufacturer to reliably predict the performance of fans from measurements on down-scaled test fans. The commonly used scale-up formulas give satisfactorily results only near the design point, where inertia losses are small in comparison to frictional losses. At part- and overload the inertia losses are dominant and the scale-up formulas used so far fail. In 2013 Pelz and Stonjek introduced a new scaling method which fullfills the demands ( [1], [2]). This method considers the influence of surface roughness and geometric variations on the performance. It consists basically of two steps: Initially, the efficiency is scaled. Efficiency scaling is derived analytically from the definition of the total efficiency. With the total derivative it can be shown that the change of friction coefficient is inversely proportional to the change of efficiency of a fan. The second step is shifting the performance characteristic to a higher value of flow coefficient. It is the task of this work to improve the scaling method which was previously introduced by Pelz and Stonjek by treating the rotor/impeller and volute/stator separately. The validation of the improved scale-up method is performed with test data from two axial fans with a diameter of 1000 mm/250mm and three centrifugal fans with 2240mm/896mm/224mm diameter. The predicted performance characteristics show a good agreement to test data.

The Effect of Inlet Distortion on the Performance Characteristics of a Centrifugal Compressor

1983 ◽  
Vol 105 (2) ◽  
pp. 223-230 ◽  
Author(s):  
I. Ariga ◽  
N. Kasai ◽  
S. Masuda ◽  
Y. Watanabe ◽  
I. Watanabe
Keyword(s):  
Centrifugal Compressor ◽  
Total Pressure ◽  
Performance Characteristics ◽  
Performance Tests ◽  
Velocity Measurements ◽  
Test Rig ◽  
Low Speed ◽  
Inlet Distortion ◽  
Surge Margin ◽  
The Given

The present paper concerns itself with the effects of total pressure (and thus velocity) distortion on performance characteristics and surge margin of centrifugal compressors. Both radial and circumferential distortions were investigated. The performance tests as well as the velocity measurements within the impeller passages were carried out with a low-speed compressor test rig with the inlet honeycomb as the distortion generators and compared with the case of “no distortion” as a datum. The results indicated that the inlet distortion exerted unfavorable influences on the efficiency and the surge margin of the given compressor, though the influence of the radial distortion was much stronger than that of the circumferential one. Various distortion indices were further examined in order to correlate the performance to the inlet distortion.

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