Some Experiments at Low Speed on Compressor Cascades

1967 ◽  
Vol 89 (3) ◽  
pp. 427-436 ◽  
Author(s):  
D. Pollard ◽  
J. P. Gostelow
Keyword(s):  
Axial Velocity ◽  
Velocity Ratio ◽  
Turbulence Level ◽  
Low Speed ◽  
Pressure Distributions ◽  
Blade Row ◽  
Testing Techniques ◽  
Almost All ◽  
Experimental Pressure ◽  
Good Agreement

Some results of recent work on low-speed cascade tunnels are described. Preliminary investigations, directed toward the analysis and improvement of the airflow and testing techniques, revealed that, when porous sidewall suction was employed, almost all change in axial velocity occurred within the blade row. Variation of axial velocity ratio, aspect ratio, Reynolds number, and turbulence level for one particular cascade facilitated an explanation of differences between the results of early British and American cascade tests. More recently, work has involved cascade tests on an analytically derived cascade. Good agreement was obtained between theoretical and experimental pressure distributions and profile boundary layers.

Secondary Flow in Cascades: The Effect of Axial Velocity Ratio

1974 ◽  
Vol 16 (6) ◽  
pp. 402-407 ◽  
Author(s):  
H. Marsh
Keyword(s):  
Secondary Flow ◽  
Incompressible Flow ◽  
Axial Velocity ◽  
Velocity Ratio ◽  
Guide Vanes ◽  
Inlet Guide Vanes ◽  
Blade Row ◽  
Flow Through ◽  
The Difference ◽  
Circulation Theorem

By considering the flow through a many-bladed cascade, a simple theory is developed for the effect of a change in axial velocity on the secondary flow at exit from a cascade. An expression is derived for the difference in the time taken for fluid particles to travel over the two surfaces of the blade and this is used, along with Kelvin's circulation theorem for incompressible flow, to obtain an equation for the distributed secondary vorticity. It is shown that for the row of inlet guide vanes tested by Gregory-Smith (1)†, the change of axial velocity across the blade row has a significant effect on the secondary vorticity.

Rotor-Stator Interactions in a Four-Stage Low-Speed Axial Compressor—Part I: Unsteady Profile Pressures and the Effect of Clocking

2004 ◽  
Vol 126 (4) ◽  
pp. 507-518 ◽  
Author(s):  
Ronald Mailach ◽  
Konrad Vogeler
Keyword(s):  
Pressure Distribution ◽  
Axial Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Experimental Investigations ◽  
Low Speed ◽  
Unsteady Aerodynamic ◽  
Pressure Distributions ◽  
Blade Row ◽  
Pressure Changes

This two-part paper presents detailed experimental investigations of unsteady aerodynamic blade row interactions in the four-stage Low-Speed Research Compressor of Dresden. In part I of the paper the unsteady profile pressure distributions for the nominal setup of the compressor are discussed. Furthermore, the effect of blade row clocking on the unsteady profile pressures is investigated. Part II deals with the unsteady aerodynamic blade forces, which are calculated from the measured profile pressure distributions. The unsteady pressure distributions were analyzed in the first, a middle and the last compressor stage both on the rotor and stator blades. The measurements were carried out on pressure side and suction side at midspan. Several operating points were investigated. A complex behavior of the unsteady profile pressures can be observed, resulting from the superimposed influences of the wakes and the potential effects of several up- and downstream blade rows of the four-stage compressor. The profile pressure changes nearly simultaneously along the blade chord if a disturbance arrives at the leading edge or the trailing edge of the blade. Thus the unsteady profile pressure distribution is nearly independent of the convective wake propagation within the blade passage. A phase shift of the reaction of the blade to the disturbance on the pressure and suction side is observed. In addition, clocking investigations were carried out to distinguish between the different periodic influences from the surrounding blade rows. For this reason the unsteady profile pressure distribution on rotor 3 was measured, while stators 1–4 were separately traversed stepwise in the circumferential direction. Thus the wake and potential effects of the up- and downstream blade rows on the unsteady profile pressure could clearly be distinguished and quantified.

Rotor-Stator Interactions in a Four-Stage Low-Speed Axial Compressor: Part I — Unsteady Profile Pressures and the Effect of Clocking

2004 ◽  
Author(s):  
Ronald Mailach ◽  
Konrad Vogeler
Keyword(s):  
Pressure Distribution ◽  
Axial Compressor ◽  
Leading Edge ◽  
Suction Side ◽  
Experimental Investigations ◽  
Complex Behaviour ◽  
Low Speed ◽  
Unsteady Aerodynamic ◽  
Pressure Distributions ◽  
Blade Row

This two-part paper presents detailed experimental investigations of unsteady aerodynamic blade row interactions in the four-stage Low-Speed Research Compressor of Dresden. In part I of the paper the unsteady profile pressure distributions for the nominal setup of the compressor are discussed. Furthermore the effect of blade row clocking on the unsteady profile pressures is investigated. Part II deals with the unsteady aerodynamic blade forces, which are calculated from the measured profile pressure distributions. The unsteady pressure distributions were analysed in the first, a middle and the last compressor stage both on the rotor and stator blades. The measurements were carried out on pressure side and suction side at midspan. Several operating points were investigated. A complex behaviour of the unsteady profile pressures can be observed, resulting from the superimposed influences of the wakes and the potential effects of several up- and downstream blade rows of the four-stage compressor. The profile pressure changes nearly simultaneously along the blade chord if a disturbance arrives at the leading edge or the trailing edge of the blade. Thus the unsteady profile pressure distribution is nearly independent of the convective wake propagation within the blade passage. A phase shift of the reaction of the blade to the disturbance on the pressure and suction side is observed. In addition clocking investigations were carried out to distinguish between the different periodic influences from the surrounding blade rows. For this reason the unsteady profile pressure distribution on rotor 3 was measured, while stator 1–4 were separately traversed stepwise in the circumferential direction. Thus the wake and potential effects of the up- and downstream blade rows on the unsteady profile pressure could clearly be distinguished and quantified.

Two-dimensional flow of a compressible fluid past given curved obstacles with infinite wakes

1955 ◽  
Vol 227 (1170) ◽  
pp. 367-386 ◽  
Keyword(s):  
Flow Separation ◽  
Subsonic Flow ◽  
Constant Pressure ◽  
Boundary Layer Separation ◽  
Two Dimensional ◽  
Pressure Distributions ◽  
Infinite Extent ◽  
Two Dimensional Flow ◽  
Experimental Pressure ◽  
Good Agreement

This paper extends in a number of ways the classical Helmholtz theory of incompressible flow about obstacles behind which are constant-pressure cavities or ‘bubbles’ of infinite extent. The theory given in the paper applies to compressible subsonic flow about given curved obstacles with bubble pressures varying down the wake. As an example the flow is calculated past a circular cylinder for a number of points of flow separation and Mach numbers. When the points of flow separation are the same as those found experimentally, the theoretical and experimental pressure distributions over the cylinder are in good agreement. It is shown that the point of flow separation for ‘proper’ cavitation is almost coincident with the point found experimentally for laminar boundary-layer separation.

Blunt Trailing Edge Shear Wake Development With Turbulent In-Flow Boundary Layers

2005 ◽  
Author(s):  
Dhanalakshmi Challa ◽  
Joe Klewicki
Keyword(s):  
Boundary Layer ◽  
Shear Layer ◽  
Boundary Layers ◽  
High Speed ◽  
Velocity Ratio ◽  
Free Shear Layer ◽  
Low Speed ◽  
Axial Pressure Gradient ◽  
Layer Flow ◽  
Good Agreement

Experiments are conducted to explore the structural mechanisms involved in the post-separation evolution of a wall-bounded to a free-shear turbulent flow. At the upstream, both the boundary layers are turbulent. Experiments were conducted in a two-stream shear-layer tunnel, under a zero axial pressure gradient shear-wake configuration. A velocity ratio near 2 was explored. Profile data were collected with a single wire probe at various locations downstream of the blunt separation lip. With this set of measurements, mean profile, axial intensity and measures of profile evolution indicate that the predominant shift from turbulent boundary layer to free shear-layer like behavior occurs between the downstream locations x/θ = 13.7 & 27.4, where θ is the upstream momentum deficit thickness on the low-speed stream. The shear wake width is observed to be nominally constant with the downstream position. Axial velocity spectra show that the transition from boundary layer flow to shear flow occurs earlier in high-speed stream when compared to low speed stream. Strouhal number, Sto, of initial vortex rollup based on initial momentum thickness was found to be 0.034, which is in very good agreement with the existing literature. Other measures are in good agreement with linear stability considerations found in the literature.

Paper 32: The Effects of Reynolds Number, Turbulence Intensity, and Axial Velocity Ratio on Compressor Blade Performance

1969 ◽  
Vol 184 (7) ◽  
pp. 93-100
Author(s):  
R. Shaw
Keyword(s):  
Reynolds Number ◽  
Axial Velocity ◽  
Free Stream ◽  
Velocity Ratio ◽  
Compressor Blade ◽  
Free Stream Turbulence ◽  
Blade Row ◽  
Reynolds Number Effects ◽  
Side Walls ◽  
Series Of Experiments

The paper describes a series of experiments that were conducted on a compressor blade of conventional geometry, in a low-speed research compressor, to determine the effect of Reynolds number on the performance of (1) an isolated rotor blade row when the free-stream turbulence is low, (2) the isolated rotor at a higher level of turbulence, and (3) the rotor row when unsteadiness is introduced by a set of inlet guide vanes of zero camber and zero stagger. In each case the axial velocity ratio at mid-span was measured and tests were carried out under similar conditions on a two-dimensional cascade of blades using a wind tunnel with porous side walls. The compressor results indicate that there are significant Reynolds number effects under these conditions, and the comparison with the cascade results demonstrates that there is a difference in performance between the rotating row and the cascade.

A Theoretical Analysis of the Viscous Flow in a Narrowly Spaced Radial Diffuser

1957 ◽  
Vol 24 (1) ◽  
pp. 9-15
Author(s):  
Henry W. Woolard
Keyword(s):  
Turbulent Flow ◽  
Viscous Flow ◽  
Plane Surface ◽  
Flow Analysis ◽  
Theoretical Method ◽  
Radial Pressure ◽  
Pressure Distributions ◽  
Disk Valve ◽  
Experimental Pressure ◽  
Good Agreement

Abstract A theoretical method for calculating the radial pressure distribution for laminar viscous flow in a narrowly spaced radial diffuser having arbitrarily shaped walls deviating only moderately from a plane surface is developed. The analysis as it stands is also directly applicable to turbulent flow in the initial inlet region of a diffuser. Additional work is necessary to obtain a complete turbulent-flow analysis. Pressure distributions calculated by the laminar-flow theory show reasonably good agreement with the limited experimental pressure distributions available at the time of the analysis. Fairly good agreement also is obtained for the performance of a disk-valve element.

Rotor-Stator Interactions in a Four-Stage Low-Speed Axial Compressor: Part II — Unsteady Aerodynamic Forces of Rotor and Stator Blades

2004 ◽  
Author(s):  
Ronald Mailach ◽  
Lutz Mu¨ller ◽  
Konrad Vogeler
Keyword(s):  
Aerodynamic Force ◽  
Axial Compressor ◽  
Stability Limit ◽  
Experimental Investigations ◽  
Low Speed ◽  
Unsteady Aerodynamic ◽  
Pressure Distributions ◽  
Third Stage ◽  
Blade Row ◽  
Stator Blade

This two-part paper presents detailed experimental investigations of unsteady aerodynamic blade row interactions in the four-stage Low-Speed Research Compressor of Dresden. In part I of the paper the unsteady profile pressure distributions for the nominal setup of the compressor are discussed. Furthermore the effect of blade row clocking on the unsteady profile pressures is investigated. Part II deals with the unsteady aerodynamic blade forces, which are determined from the measured profile pressure distributions. A method to calculate the aerodynamic blade forces on the basis of the experimental data is presented. The resulting aerodynamic blade forces are discussed for the rotor and stator blade rows of the first stage and the third stage of the compressor. Different operating points between design point and stability limit of the compressor were chosen to investigate the influence of loading on the aerodynamic force excitation. The time traces and the frequency contents of the unsteady aerodynamic blade force are discussed. Strong periodic influences of the incoming wakes and of potential effects of downstream blade rows can be observed. The amplitude and shape of the unsteady aerodynamic blade force depend on the interaction of the superimposed influences of the blade rows.

Rotor-Stator Interactions in a Four-Stage Low-Speed Axial Compressor—Part II: Unsteady Aerodynamic Forces of Rotor and Stator Blades

2004 ◽  
Vol 126 (4) ◽  
pp. 519-526 ◽  
Author(s):  
Ronald Mailach ◽  
Lutz Mu¨ller ◽  
Konrad Vogeler
Keyword(s):  
Aerodynamic Force ◽  
Axial Compressor ◽  
Stability Limit ◽  
Experimental Investigations ◽  
Low Speed ◽  
Unsteady Aerodynamic ◽  
Pressure Distributions ◽  
Third Stage ◽  
Blade Row ◽  
Stator Blade

This two-part paper presents detailed experimental investigations of unsteady aerodynamic blade row interactions in the four-stage low-speed research compressor of Dresden. In Part I of the paper the unsteady profile pressure distributions for the nominal setup of the compressor are discussed. Furthermore the effect of blade row clocking on the unsteady profile pressures is investigated. Part II deals with the unsteady aerodynamic blade forces, which are determined from the measured profile pressure distributions. A method to calculate the aerodynamic blade forces on the basis of the experimental data is presented. The resulting aerodynamic blade forces are discussed for the rotor and stator blade rows of the first stage and the third stage of the compressor. Different operating points between design point and stability limit of the compressor were chosen to investigate the influence of loading on the aerodynamic force excitation. The time traces and the frequency contents of the unsteady aerodynamic blade force are discussed. Strong periodic influences of the incoming wakes and of potential effects of downstream blade rows can be observed. The amplitude and shape of the unsteady aerodynamic blade force depend on the interaction of the superimposed influences of the blade rows.

Computer Modeling of a Tire under Cornering Loads

1989 ◽  
Vol 17 (2) ◽  
pp. 86-99 ◽  
Author(s):  
I. Gardner ◽  
M. Theves
Keyword(s):  
Finite Element Analysis ◽  
Geometric Approach ◽  
Lateral Force ◽  
Slip Angle ◽  
Element Analysis ◽  
Pressure Distributions ◽  
Slip Effects ◽  
Improved Accuracy ◽  
Nonlinear Geometric ◽  
Good Agreement

Abstract During a cornering maneuver by a vehicle, high forces are exerted on the tire's footprint and in the contact zone between the tire and the rim. To optimize the design of these components, a method is presented whereby the forces at the tire-rim interface and between the tire and roadway may be predicted using finite element analysis. The cornering tire is modeled quasi-statically using a nonlinear geometric approach, with a lateral force and a slip angle applied to the spindle of the wheel to simulate the cornering loads. These values were obtained experimentally from a force and moment machine. This procedure avoids the need for a costly dynamic analysis. Good agreement was obtained with experimental results for self-aligning torque, giving confidence in the results obtained in the tire footprint and at the rim. The model allows prediction of the geometry and of the pressure distributions in the footprint, since friction and slip effects in this area were considered. The model lends itself to further refinement for improved accuracy and additional applications.

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