Aerodynamic Design and Analysis of a High Pressure Ratio Aspirated Compressor Stage

2000 ◽  
Author(s):  
Ali A. Merchant ◽  
Mark Drela ◽  
Jack L. Kerrebrock ◽  
John J. Adamczyk ◽  
Mark Celestina
Keyword(s):  
Boundary Layer ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Adverse Pressure Gradient ◽  
Compressor Stage ◽  
High Pressure Ratio ◽  
Total Pressure Ratio ◽  
Isentropic Efficiency

The pressure ratio of axial compressor stages can be significantly increased by controlling the development of blade and endwall boundary layers in regions of adverse pressure gradient by means of boundary layer suction. This concept is validated and demonstrated through the design and analysis of a unique aspirated compressor stage which achieves a total pressure ratio of 3.5 at a tip speed of 1500 ft/s. The aspirated stage was designed using an axisymmetric through-flow code coupled with a quasi three-dimensional cascade plane code with inverse design capability. Validation of the completed design was carried out with three-dimensional Navier-Stokes calculations. Spanwise slots were used on the rotor and stator suction surfaces to bleed the boundary layer with a total suction requirement of 4% of the inlet mass flow. Additional bleed of 3% was also required on the hub and shroud near shock impingement locations. A three-dimensional viscous evaluation of the design showed good agreement with the quasi three-dimensional design intent, except in the endwall regions. The three-dimensional viscous analysis predicted a mass averaged total pressure ratio of 3.7 at an isentropic efficiency of 93% for the rotor, and a mass averaged total pressure ratio of 3.4 at an isentropic efficiency of 86% for the stage.

Some Experiments With a Supersonic Axial Compressor Stage

1987 ◽  
Vol 109 (3) ◽  
pp. 388-397 ◽  
Author(s):  
A. J. Wennerstrom
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Design Flow ◽  
Vortex Generators ◽  
Boundary Layer Control ◽  
Compressor Stage ◽  
Design Speed ◽  
Isentropic Efficiency ◽  
Layer Control

Between 1970 and 1974, ten variants of a supersonic axial compressor stage were designed and tested. These included two rotor configurations, three rotor tip clearances, addition of boundary-layer control consisting of vortex generators on both the outer casing and the rotor, and the introduction of slots in the stator vanes. Design performance objectives were a stage total pressure ratio of 3.0 with an isentropic efficiency of 0.82 at a tip speed of 1600 ft/s (488 m/s). The first configuration passed only 70 percent of design flow at design speed, achieving a stage pressure ratio of 2.25 at a peak stage isentropic efficiency of 0.61. The rotor was grossly separated. The tenth variant passed 91.4 percent of design flow at design speed, producing a stage pressure ratio of 3.03 with an isentropic efficiency of 0.75. The rotor achieved a pressure ratio of 3.59 at an efficiency of 0.87 under the same conditions. Major conclusions were that design tools available today would undoubtedly permit the original goals to be met or exceeded. However, the application for such a design is currently questionable because efficiency goals considered acceptable for most current programs have risen considerably from the level considered acceptable at the inception of this effort. Splitter vanes placed in the rotor permitted very high diffusion levels to be achieved without stalling. However, viscous effects causing three-dimensional flows violating the assumption of flow confined to concentric stream tubes were so strong that a geometry optimization does not appear practical without a three-dimensional, viscous analysis. Passive boundary-layer control in the form of vortex generators and slots does appear to offer some benefit under certain circumstances.

Experimental Investigation of Aspiration in a Multi-Stage High-Speed Axial-Compressor

2016 ◽  
Author(s):  
Jan Siemann ◽  
Ingolf Krenz ◽  
Joerg R. Seume
Keyword(s):  
Flow Field ◽  
Total Pressure ◽  
High Speed ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Reference Configuration ◽  
Corner Separation ◽  
Part Load ◽  
Total Pressure Ratio ◽  
Isentropic Efficiency

Reducing the fuel consumption is a main objective in the development of modern aircraft engines. Focusing on aircraft for mid-range flight distances, a significant potential to increase the engines overall efficiency at off-design conditions exists in reducing secondary flow losses of the compressor. For this purpose, Active Flow Control (AFC) by aspiration or injection of fluid at near wall regions is a promising approach. To experimentally investigate the aerodynamic benefits of AFC by aspiration, a 4½-stage high-speed axial-compressor at the Leibniz Universitaet Hannover was equipped with one AFC stator row. The numerical design of the AFC-stator showed significant hub corner separations in the first and second stator for the reference configuration at the 80% part-load speed-line near stall. Through the application of aspiration at the first stator, the numerical simulations predict the complete suppression of the corner separation not only in the first, but also in the second stator. This leads to a relative increase in overall isentropic efficiency of 1.47% and in overall total pressure ratio of 4.16% compared to the reference configuration. To put aspiration into practice, the high-speed axial-compressor was then equipped with a secondary air system and the AFC stator row in the first stage. All experiments with AFC were performed for a relative aspiration mass flow of less than 0.5% of the main flow. Besides the part-load speed-lines of 55% and 80%, the flow field downstream of each blade row was measured at the AFC design point. Experimental results are in good agreement with the numerical predictions. The use of AFC leads to an increase in operating range at the 55% part-load speed-line of at least 19%, whereas at the 80% part-load speed-line no extension of operating range occurs. Both speed-lines, however, do show a gain in total pressure ratio and isentropic efficiency for the AFC configuration compared to the reference configuration. Compared to the AFC design point, the isentropic efficiency ηis rises by 1.45%, whereas the total pressure ratio Πtot increases by 1.47%. The analysis of local flow field data shows that the hub corner separation in the first stator is reduced by aspiration, whereas in the second stator the hub corner separation slightly increases. The application of AFC in the first stage further changes the stage loading in all downstream stages. While the first and third stage become unloaded by application of AFC, the loading in terms of the De-Haller number increases in the second and especially in the fourth stage. Furthermore, in the reference as well as in the AFC configuration, the fourth stator performs significantly better than predicted by numerical results.

Time Resolved Simulation and Experimental Validation of the Flow in Axial Slot Casing Treatments for Transonic Axial Compressors

2008 ◽  
Author(s):  
Giovanni A. Brignole ◽  
Florian C. T. Danner ◽  
Hans-Peter Kau
Keyword(s):  
Mass Flow ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Compressor Stage ◽  
Time Resolved ◽  
Transonic Compressor ◽  
Design Speed ◽  
Casing Treatments ◽  
Total Pressure Ratio

Building on the experience of previous investigations, a casing treatment was developed and applied to an axial transonic compressor stage, in literature referred to as Darmstadt Rotor 1. The aerodynamics of the experimental compressor stage was improved by applying axially orientated semicircular slots to the original plain casing, which both enhanced the operating range and design point efficiency. A gain in total pressure ratio along the entire design speed line was also observed. Within the scope of this study four different axial casing treatments were designed. Their effect on the flow in a transonic axial compressor stage was investigated parametrically using time-resolved 3D-FANS simulations with a mesh of approximately 4.8 · 106 grid points. This research aims to identify correlations between the geometrical cavity design and the changed channel flow. The findings help to formulate parameters for evaluating the performance of casing treatments. These criteria can further be used as target functions in the design optimisation process. The predicted behaviour of the transonic compressor was validated against experiments as well as an alternative numerical model, the non-linear harmonic method. Both confirmed the effect of the slots in raising efficiency as well as moving the design speed line towards higher pressure ratios. In the experiments, the addition of the slots increased the total pressure ratio at stall conditions by more than 5% and reduced mass flow from 87.5% of the design mass flow to less than 77.5% compared to the original geometry.

Research on Optimization of the Design(Inverse) Issue of S2 Surface of Axial Compressor Based on Genetic Algorithm

2020 ◽  
Author(s):  
Zijing Chen ◽  
Bo Liu ◽  
Xiaoxiong Wu
Keyword(s):  
Genetic Algorithm ◽  
Total Pressure ◽  
Fitness Function ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Local Data ◽  
Real Coded Genetic Algorithm ◽  
Overall Efficiency ◽  
Total Pressure Ratio ◽  
Peak Value

Abstract In order to further improve the effectiveness of design(inverse) issue of S2 surface of axial compressor, a design method of optimization model based on real-coded genetic algorithm is instructed, with a detailed description of some important points such as the population setting, the fitness function design and the implementation of genetic operator. The method mainly takes the pressure ratio, the circulation as the optimization variables, the total pressure ratio and the overall efficiency of the compressor as the constraint condition and the decreasing of the diffusion factor of the compressor as the optimization target. In addition, for the propose of controlling the peak value of some local data after the optimization, a local optimization strategy is proposed to make the method achieve better results. In the optimization, the streamline curvature method is used to perform the iterative calculation of the aerodynamic parameters of the S2 flow surface, and the polynomial fitting method is used to optimize the dimensionality of the variables. The optimization result of a type of ten-stage axial compressor shows that the pressure ratio and circulation parameters have significant effect on the diffusion factor’s distribution, especially for the rotor pressure ratio. Through the optimization, the smoothness of the mass-average pressure ratio distribution curve of the rotors at all stages of the compressor is improved. The maximum diffusion factors in spanwise of rotor rows at the first, fifth and tenth stage of the compressor are reduced by 1.46%, 12.53% and 8.67%, respectively. Excluding the two calculation points at the root and tip of the blade because of the peak value, the average diffusion factors in spanwise are reduced by 1.28%, 3.46%, and 1.50%, respectively. For the two main constraints, the changes of the total pressure ratio and overall efficiency are less than 0.03% and 0.032%, respectively. In the end, a 3-d CFD numerical result is given to testify the effects of the optimization, which shows that the loss in the compressor is decreased by the optimization algorithm.

Assessment of Various Turbulence Models in a High Pressure Ratio Centrifugal Compressor With an Object Oriented CFD Code

2012 ◽  
Vol 134 (6) ◽  
Author(s):  
Luca Mangani ◽  
Ernesto Casartelli ◽  
Sebastiano Mauri
Keyword(s):  
Boundary Layer ◽  
High Pressure ◽  
Pressure Gradient ◽  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Turbulence Models ◽  
Object Oriented ◽  
Adverse Pressure Gradient ◽  
High Mass ◽  
High Pressure Ratio

The flow field in a high pressure ratio centrifugal compressor with a vaneless diffuser has been investigated numerically. The main goal is to assess the influence of various turbulence models suitable for internal flows with an adverse pressure gradient. The numerical analysis is performed with a 3D RANS in-house modified solver based on an object-oriented open-source library. According to previous studies from varying authors, the turbulence model is believed to be the key parameter for the discrepancy between experimental and numerical results, especially at high pressure ratios and high mass-flow. Particular care has been taken at the wall, where a detailed integration of the boundary layer has been applied. The results present different comparisons between the models and experimental data, showing the influence of using advanced turbulence models. This is done in order to capture the boundary layer behavior, especially in large adverse pressure gradient single stage machinery.

Numerical Investigation on the Effects of Circumferential Coverage of Injection in a Transonic Compressor With Discrete Tip Injection

2014 ◽  
Author(s):  
Wei Wang ◽  
Wuli Chu ◽  
Haoguang Zhang ◽  
Yanhui Wu
Keyword(s):  
Total Pressure ◽  
Pressure Ratio ◽  
Time Lag ◽  
Three Dimensional ◽  
Stability Margin ◽  
Transonic Compressor ◽  
Blade Tip ◽  
Tip Injection ◽  
The Stability ◽  
Total Pressure Ratio

Discrete tip injection upstream of the rotor tip is an effective technique to extend stability margin for a compressor system in an aeroengine. The current study investigates the effects of injectors’ circumferential coverage on compressor performance and stability using time-accurate three-dimensional numerical simulations for multi passages in a transonic compressor. The percentage of circumferential coverage for all the six injectors ranges from 6% to 87% for the five investigated configurations. Results indicate that circumferential coverage of tip injection can greatly affect compressor stability and total pressure ratio, but has little influence on adiabatic efficiency. The improvement of compressor total pressure ratio is linearly related with the increasing circumferential coverage. The unsteady flow fields show that there exists a non-ignorable time lag of the injection effects between the passage inlet and outlet, and blade tip loading will not decline until the injected flow reaches the passage outlet. Stability improves sharply with the increasing circumferential coverage when the coverage is less than 27%, but increases flatly for the rest. It is proven that the injection efficiency which is a measurement of averaged blockage decrement in the injected region is an effective guideline to predict the stability improvement.

Numerical Investigation of Impeller Tip Tailoring and its Impact on Aerodynamic Design of a Centrifugal Compressor’s Impeller

2014 ◽  
Author(s):  
Ashvin Mahajan ◽  
Lieven Baert ◽  
Michaël Leborgne ◽  
Timothée Lonfils ◽  
I. Gede Parwatha ◽  
...  
Keyword(s):  
Design Optimization ◽  
Significant Contribution ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Aerodynamic Design ◽  
High Pressure Ratio ◽  
Important Improvement ◽  
Geometrical Features ◽  
Isentropic Efficiency

The current research focuses on the aerodynamic design of a centrifugal compressor and the effect of tip tailoring on the aerodynamic impeller efficiency. To this extent a high-fidelity multi-point design optimization process has been developed and exploited on a high pressure ratio transonic impeller. By manipulating the shape of the impeller blades and endwalls and by including advanced geometrical features such as winglets on the impeller blades, the behavior of the impeller flow has been investigated. Here, the results of three-dimensional RANS simulations with the Spalart-Allmaras turbulence model on a structured multi-block mesh is used for the evaluation of the flow characteristics. In the context of radial machines, the results of the aerodynamic design optimization show an important improvement of the impeller isentropic efficiency compared to the reference impeller, with a significant contribution from the presence of the impeller tip winglets. Furthermore, the integration of the impeller winglet has encouraged this study to provide a detailed analysis on the impeller flow structures in order to have a better understanding of the effects of tip tailoring on impeller performance.

Study of Supersonic Flowfield With Secondary Injection

2004 ◽  
Author(s):  
D. Sun ◽  
R. S. Amano
Keyword(s):  
Total Pressure ◽  
Boundary Layer Thickness ◽  
Stokes Equations ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Navier Stokes ◽  
Navier Stokes Equations ◽  
Weighted Essentially Nonoscillatory ◽  
Secondary Injection ◽  
Total Pressure Ratio

Two and three-dimensional steady flowfields generated by transverse secondary injection into a supersonic flow, was simulated by solving the Favre-averaged Navier-Stokes equations using the weighted essentially nonoscillatory (WENO) schemes. Both the two-dimensional and three-dimensional results are given. Some parameters affecting the penetration height and separation length of the interactive flowfield, including the total pressure ratio of the jet to the freestream, the boundary layer thickness, slot width, the Mach number of the freestream and injection, the jet angle, and the shape of the injection orifice in the 3D flowfield, were calculated in more detail.

A Comparison between Measured and Computed Flow Fields in a Transonic Compressor Rotor

1980 ◽  
Vol 102 (4) ◽  
pp. 883-889 ◽  
Author(s):  
P. W. McDonald ◽  
C. R. Bolt ◽  
R. J. Dunker ◽  
H. B. Weyer
Keyword(s):  
Mach Number ◽  
Total Pressure ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Computational Procedure ◽  
Operating Conditions ◽  
Transonic Compressor ◽  
Compressor Rotor ◽  
Pressure Profiles

The flow field within the rotor of a transonic axial compressor has been computed and compared to measurements obtained with an advanced laser velocimeter. The compressor was designed for a total pressure ratio of 1.51 at a relative tip Mach number of 1.4. The comparisons are made at 100 percent design speed (20,260 RPM) with pressure ratios corresponding to peak efficiency, near surge, and wide open discharge operating conditions. The computational procedure iterates between a blade-to-blade calculation and an intrablade through flow calculation. Calculated Mach number contours, surface pressure distributions, and exit total pressure profiles are in agreement with the experimental data demonstrating the usefulness of quasi three-dimensional calculations in compressor design.

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