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 Study of a High-Throughflow Transonic Axial Compressor Stage

1984 ◽  
Vol 106 (3) ◽  
pp. 552-560 ◽  
Author(s):  
A. J. Wennerstrom
Keyword(s):  
Experimental Study ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Experimental Results ◽  
Vortex Generators ◽  
Compressor Stage ◽  
Stall Margin ◽  
Transonic Axial Compressor ◽  
Design Speed ◽  
Isentropic Efficiency

Design information and experimental results are presented for a transonic axial compressor stage passing 40 lbs/s-ft2 frontal area (195 Kg/s-m2) with a pressure ratio of 1.95 at 1500 ft/s (457 m/s) tip speed. The design incorporates several unusual features that helped it achieve a peak isentropic efficiency over 88 percent at design speed. The compressor was evaluated at three rotor tip clearances and an optimum was found. Vortex generators placed upstream on the casing proved relatively ineffective in influencing stall margin. Vortex generators installed on the rotor did improve stall margin and also increased efficiency at speeds of 90 percent and below.

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.

Boundary Layer Control of an Axial Compressor Cascade Using Nonconventional Vortex Generators

2015 ◽  
Author(s):  
Ahmed M. Diaa ◽  
Mohammed F. El-Dosoky ◽  
Mahmoud A. Ahmed ◽  
Omar E. Abdel-Hafez
Keyword(s):  
Boundary Layer ◽  
Passive Control ◽  
Axial Compressor ◽  
Vortex Generators ◽  
Boundary Layer Control ◽  
Geometrical Parameters ◽  
Compressor Cascade ◽  
Suction Surface ◽  
Flow Equations ◽  
Layer Control

Boundary layer control plays a decisive role in controlling the performance of axial compressor. Vortex generators are well known as passive control devices of the boundary layer. In the current study, two nonconventional types of vortex generators are used and their effects are investigated. The used vortex generators are doublet, and wishbone. Three dimensional turbulent compressible flow equations through an axial compressor cascade are numerically simulated. Comparisons between cascade with and without vortex generators are performed to predict the effect of inserting vortex generator in the overall performance of the axial compressor. Results indicate that using vortex generators leads to eliminate or delay the separation on the blade suction surface, as well as the endwall. Furthermore, the effects of the vortex generators and their geometrical parameters on the aerodynamic performance of the cascade are documented. In conclusion, while the investigated vortex generators cause a slight increase in the total pressure loss, a significant reduction in the skin friction coefficient at the bottom endwall is found. This reduction is estimated to be about 46% using doublet and 32% using wishbone.

Computation of Three-Dimensional Flow Fields Through Rotating Blade Rows and Comparison With Experiment

1982 ◽  
Vol 104 (2) ◽  
pp. 394-400 ◽  
Author(s):  
K. P. Sarathy
Keyword(s):  
Pressure Ratio ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Peak Efficiency ◽  
Three Dimensional Flow ◽  
Flow Solver ◽  
Rotating Blade ◽  
Blade Row ◽  
Time Marching ◽  
Design Speed

A three-dimensional inviscid time-marching calculation solving the unsteady Euler equations in a coordinate system rotating with the blade row has been developed, based on the Denton flow solver. This calculation was used to compute the flow field through the rotor of a transonic axial compressor and compared to measurements made with an advanced laser velocimeter at DFVLR. The comparison is made at design speed at pressure ratio corresponding to peak efficiency. Comparisons of the calculated and experimentally determined Mach number contours indicate excellent agreement in the entrance region where the viscous blockage effects are small. The methodology of the analysis is also described in this paper.

Evaluation of a High Hub/Tip Ratio Centrifugal Compressor

1970 ◽  
Vol 92 (3) ◽  
pp. 419-428 ◽  
Author(s):  
F. G. Groh ◽  
G. M. Wood ◽  
R. S. Kulp ◽  
D. P. Kenny
Keyword(s):  
Centrifugal Compressor ◽  
Pressure Ratio ◽  
Axial Compressor ◽  
Tip Clearance ◽  
Total Efficiency ◽  
Compressor Stage ◽  
Vaneless Diffuser ◽  
Centrifugal Stage ◽  
Design Speed ◽  
Multistage Axial Compressor

A centrifugal compressor stage with an unusually high inlet hub/tip ratio of 0.87 was designed for a pressure ratio of 2.0 at a corrected mass flow of 2.45 lb per sec. The geometry was selected so that the centrifugal stage could replace several of the last stages of a multistage axial compressor. The stage was tested with two diffuser schemes. One diffuser consisted of a series of drilled conical pipes, whereas the other employed multirow vaned cascades. Sea level aerodynamic tests of the compressor stage with each diffuser showed a peak total-to-total efficiency at design speed of 83.8 percent for the pipe diffuser and 82.9 percent for the vaned cascade diffuser. Additional tests were conducted with a vaneless diffuser to determine effects of impeller discharge tip clearance and inlet prewhirl on impeller performance.

Experimental Study of the Flow Field Within a Transonic Axial Compressor Rotor by Laser Velocimetry and Comparison With Through-Flow Calculations

1978 ◽  
Vol 100 (2) ◽  
pp. 279-286 ◽  
Author(s):  
R. J. Dunker ◽  
P. E. Strinning ◽  
H. B. Weyer
Keyword(s):  
Flow Field ◽  
Pressure Ratio ◽  
Analytical Data ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Compressor Rotor ◽  
Through Flow ◽  
Equivalent Mass ◽  
Transonic Axial Compressor ◽  
Design Speed

The flow field ahead, within, and behind the rotor of a transonic axial compressor designed for a total pressure ratio of 1.51 at a relative tip Mach number of 1.4 has been studied in detail using an advanced laser velocimeter. The tests were carried out at 70 and 100 percent design speed (20,260 rpm) and equivalent mass flows corresponding to the point of maximum isentropic efficiency. The tests yielded quite complete data on the span- and gap-wise velocity profiles, on the three-dimensional shock waves in and outside of the rotor blade channels, and on the blade wakes. Some of the experimental results will be submitted, discussed, and compared to corresponding analytical data of a through-flow calculation. The comparison reveals considerable discrepancies inside the blade row between the two-dimensional calculation and the experiments primarily due to the loss and deviation correlations used, as well as to the distribution of losses and flow angles inside the blade channels.

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.

Experimental and Numerical Investigations on a High Pressure Ratio Centrifugal Compressor

2005 ◽  
Author(s):  
Jae Ho Choi ◽  
Ok Suck Sung ◽  
Seung-Bae Chen ◽  
Jin Shik Lim
Keyword(s):  
Centrifugal Compressor ◽  
Performance Test ◽  
Pressure Ratio ◽  
Flow Analysis ◽  
Three Dimensional ◽  
Aerodynamic Characteristics ◽  
Design Flow ◽  
Tip Clearance ◽  
Centrifugal Impeller ◽  
Compressor Stage

An aerodynamic design, flow analysis and performance test of a pressure ratio 4:1 centrifugal compressor are presented in this paper. The compressor is made up of a centrifugal impeller, a two-stage diffuser consisted of radial and axial types. The impeller has a 45 degree backswept angle and the design running tip clearance is 5% of impeller exit height. Two types of diffusers are designed for this compressor. Three-dimensional numerical analysis is performed to analyze the flows in the impeller, diffuser and deswirler considering the impeller tip clearance. A test module and rig facilities for the compressor stage performance test are designed and fabricated. The overall compressor stage performances as well as the static pressure fields on the impeller and diffuser are measured. Two diffusers of wedge and airfoil types are tested with an impeller. The calculation and test results show the airfoil diffuser has the better aerodynamic characteristics than those of wedge diffuser in the studied models.

Effect of the Inlet Velocity Profile in the Three-Dimensional Flow in a Rear Axial Compressor Stage

1988 ◽  
Vol 110 (4) ◽  
pp. 434-440 ◽  
Author(s):  
V. Cyrus
Keyword(s):  
Velocity Profile ◽  
Three Dimensional ◽  
Axial Compressor ◽  
Design Flow ◽  
Flow Coefficient ◽  
Intensity Level ◽  
Compressor Stage ◽  
Three Dimensional Flow ◽  
Inlet Velocity ◽  
Dimensional Flow

A detailed investigation of the three-dimensional flow was carried out in a low-speed rear axial compressor stage with an aspect ratio of 1. Experimental data were obtained for both an inlet velocity profile with thin endwall boundary layer thickness and a distorted inlet velocity profile with a high turbulence intensity level. The distortion was produced by a specially designed screen. The flow mechanism in the rotor and stator blade rows is analyzed for these two velocity profiles at the design flow coefficient.

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