A Method for Correcting Wall Pressure Measurements in Subsonic Compressible Flow

1991 ◽  
Vol 113 (2) ◽  
pp. 256-260 ◽  
Author(s):  
C. Ducruet
Keyword(s):  
Boundary Layer ◽  
Experimental Investigation ◽  
Mach Number ◽  
Compressible Flow ◽  
Velocity Gradient ◽  
Static Pressure ◽  
Subsonic Flow ◽  
Diameter Ratio ◽  
Wall Pressure ◽  
Pressure Measurements

A theoretical and experimental investigation has been made of the static pressure hole problem in subsonic flow. Thanks to a linearization, the effects of the boundary layer, of the velocity gradient and of the wall curvature could be separated so that a formula of correction containing three influence functions has been obtained. These functions were determined in the case of practical requirements by means of experiments made on appropriate models for two values of the depth-to-diameter ratio and for at least three values of the Mach number. Then, the method of correction has been applied to the flow around an airfoil at zero angle of attack.

Experimental investigation of aerofoil tonal noise at low Mach number

2021 ◽  
Vol 932 ◽  
Author(s):  
Prateek Jaiswal ◽  
Yann Pasco ◽  
Gyuzel Yakhina ◽  
Stéphane Moreau
Keyword(s):  
Experimental Investigation ◽  
Mach Number ◽  
Three Dimensional ◽  
Normal Modes ◽  
Wall Pressure ◽  
Far Field ◽  
Tonal Noise ◽  
Trailing Edge ◽  
Modal Shape ◽  
Low Mach Number

This paper presents an experimental investigation of aerofoil tones emitted by a controlled-diffusion aerofoil at low Mach number ( $0.05$ ), moderate Reynolds number based on the chord length ( $1.4 \times 10^{5}$ ) and moderate incidence ( $5^{\circ }$ angle of attack). Wall-pressure measurements have been performed along the suction side of the aerofoil to reveal the acoustic source mechanisms. In particular, a feedback loop is found to extend from the aerofoil trailing edge to the regions near the leading edge where the flow encounters a mean favourable pressure gradient, and consists of acoustic disturbances travelling upstream. Simultaneous wall-pressure, velocity and far-field acoustic measurements have been performed to identify the boundary-layer instability responsible for tonal noise generation. Causality correlation between far-field acoustic pressure and wall-normal velocity fluctuations has been performed, which reveals the presence of a Kelvin–Helmholtz-type modal shape within the velocity disturbance field. Tomographic particle image velocimetry measurements have been performed to understand the three-dimensional aspects of this flow instability. These measurements confirm the presence of large two-dimensional rollers that undergo three-dimensional breakdown just upstream of the trailing edge. Finally, modal decomposition of the flow has been carried out using proper orthogonal decomposition, which demonstrates that the normal modes are responsible for aerofoil tonal noise. The higher normal modes are found to undergo regular modulations in the spanwise direction. Based on the observed modal shape, an explanation of aerofoil tonal noise amplitude reduction is given, which has been previously reported in modular or serrated trailing-edge aerofoils.

On Transition From Supersonic to Subsonic Flow at Low Reynolds Numbers in a Tube

1969 ◽  
Vol 36 (2) ◽  
pp. 146-150 ◽  
Author(s):  
R. Y. Chen ◽  
J. C. Williams
Keyword(s):  
Mach Number ◽  
Static Pressure ◽  
Subsonic Flow ◽  
Supersonic Nozzle ◽  
Reynolds Numbers ◽  
Impact Pressure ◽  
Low Reynolds Numbers ◽  
Pressure Distributions ◽  
Low Reynolds ◽  
The Impact

A supersonic low-density gas stream produced in a supersonic nozzle was passed through a circular tube in which the transition from supersonic to subsonic flow took place. Static pressure distributions along the tube (and nozzle) and impact pressure distributions across the tube at several stations were measured to determine the nature of this transition. The impact pressure distributions were used, together with the local static pressure, to infer Mach number and velocity profiles in the tube. When the pressure distributions and center-line Mach number distributions are considered together, one obtains a fairly clear picture of the processes involved in the transition from supersonic to subsonic flow at low Reynolds numbers.

The pressure-hole problem

1984 ◽  
Vol 142 ◽  
pp. 251-267 ◽  
Author(s):  
C. Ducruet ◽  
A. Dyment
Keyword(s):  
Boundary Layer ◽  
Incompressible Flow ◽  
Velocity Gradient ◽  
Static Pressure ◽  
Slender Body ◽  
Complex Flows ◽  
Dimensionless Parameters ◽  
Pressure Drag ◽  
Partial Linearization

The static pressure-hole problem is investigated both theoretically and experimentally. The influence of all significant dimensionless parameters is brought to light. These parameters represent the effects of the boundary layer, of the velocity gradient and of the wall curvature. A partial linearization makes it possible to propose a formula of correction containing three influence functions which cannot be determined by the theory. A limited number of experiments on appropriate models leads to the determination of these functions in case of practical requirements. So, a method of correction is obtained, but only in incompressible flow. The previous formula has been verified in two complex flows. The importance of the correction on the pressure drag of a slender body is brought to light and the difficulties in the application on the method are emphasized.

Experimental Study on Pressure Fluctuations in the Boundary Layer of an Axisymmetric Body

2011 ◽  
Vol 66-68 ◽  
pp. 1488-1493
Author(s):  
Hong Xiao ◽  
Chao Gao ◽  
Zhen Kun Ma
Keyword(s):  
Boundary Layer ◽  
Experimental Study ◽  
Mach Number ◽  
Dynamic Pressure ◽  
Pressure Fluctuations ◽  
Axisymmetric Body ◽  
Pressure Measurements ◽  
Fluctuating Pressure ◽  
Frequency Domains ◽  
Dynamic Pressure Measurements

The characteristics of the fluctuating pressure in the boundary layer of an axisymmetric body have been investigated experimentally using dynamic pressure measurements and Schlieren photograghs. Data were acquired at subsonic and super-sonic Mach numbers. The angles of attack ranged from 0° to 5°. Pressure signals were measured simultaneously in several positions along the model and were analyzed both in the time and frequency domains. The Mach number shows the relevant influence on . Furthermore, the pressure fluctuations’ level decreases with the increasing of Mach number except M=1.15. And it is shown that, the location along the axis of the model and the angles of attack have small effect on pressure fluctuations.

Numerical Investigation of the Compressible Flow Through a Turbine Center Frame Duct

2018 ◽  
Author(s):  
Li-Wei Chen ◽  
Christian Wakelam ◽  
Jonathan Ong ◽  
Andreas Peters ◽  
Andrea Milli ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Mach Number ◽  
Numerical Investigation ◽  
Compressible Flow ◽  
Flow Behavior ◽  
Computational Domain ◽  
Turbulent Structures ◽  
Curvature Effects ◽  
Eddy Simulation ◽  
Static Pressure Distribution

Numerical investigation of the compressible flow in the Turbine Center Frame (TCF) duct was carried out using a Reynolds-averaged Navier-Stokes (RANS) method, and a Hybrid RANS/Large Eddy Simulation (HLES) method, i.e. Stress-Blended Eddy Simulation (SBES). The reference Reynolds number based on the TCF inlet condition is 530,000, and the inlet Mach number is 0.41. It is found that the boundary layer flow behavior is very sensitive to the incoming turbulence characteristics, so the upstream grid used to generate turbulence in the experiment is also included in the computational domain. Results have been validated carefully against experimental data, in terms of static pressure distribution on hub and casing walls, total pressure and Mach number profiles on the TCF measurement planes, as well as over-all pressure loss coefficient. Further, various fundamental mechanisms dictating the intricate flow phenomena, including concave and convex curvature effects, interactions between inlet turbulent structures and boundary layer, and turbulent kinetic energy budget, have been studied systematically. The current study is to evaluate the performance of HLES method for TCF flows and develop a further understanding of unsteady flow physics in the TCF duct. The results obtained in this work provide physical insight into the mechanisms relevant to the turbine intercase or TCF duct flows subjected to complex inlet disturbances.

Well Resolved Wall Pressure Measurements in a High Reynolds Number Turbulent Boundary Layer

2004 ◽  
Author(s):  
Brendan F. Perkins
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
Surface Pressure ◽  
High Reynolds Number ◽  
Wall Pressure ◽  
Pressure Measurements ◽  
Boundary Layer Turbulence ◽  
High Reynolds ◽  
Salt Playa

In order to better understand boundary layer turbulence at high Reynolds number, the fluctuating wall pressure was measured within the turbulent boundary layer that forms over the salt playa of Utah’s west desert. Pressure measurements simultaneously acquired from an array of nine microphones were analyzed and interpreted. The wall pressure intensity was computed and compared with low Reynolds number data. This analysis indicated that the variance in wall pressure increases logarithmically with Reynolds number. Computed autocorrelations provide evidence for a hierarchy of surface pressure producing scales. Space-time correlations are used to compute broadband convection velocities. The convection velocity data indicate an increasing value for larger sensor separations. To the author’s knowledge, the pressure measurements are the highest Reynolds number, well resolved measurements of fluctuating surface pressure to date.

Measurement of the Profile Drag of Compressor and Turbine Cascades and the Effect of Wakes in Exciting Vibration

1953 ◽  
Vol 57 (515) ◽  
pp. 722-725 ◽  
Author(s):  
J. M. Stephenson
Keyword(s):  
Mach Number ◽  
Compressible Flow ◽  
Total Pressure ◽  
Static Pressure ◽  
Error Curve ◽  
Exciting Vibration ◽  
Turbine Cascades ◽  
Simplified Procedure

The Melvill Jones equation for the profile drag of a single aerofoil is adapted to the case of an aerofoil in cascade, where the static pressure may be permanently raised (compressor), or lowered (turbine). A simplified procedure for measuring the drag is then described, assuming that the total pressure wake has the form of an error curve. A table of multiplying factors is given, for compressible flow up to an outlet Mach number of 0·9. Many published measurements of cascade drag have ignored this factor, with a consequent error of up to 25 per cent.

Velocity Measurements on the Forward Portion of a Cylinder

1990 ◽  
Vol 112 (2) ◽  
pp. 243-245 ◽  
Author(s):  
D. E. Paxson ◽  
R. E. Mayle
Keyword(s):  
Boundary Layer ◽  
Laminar Flow ◽  
Circular Cylinder ◽  
Vortex Shedding ◽  
Static Pressure ◽  
Free Stream ◽  
Stream Velocity ◽  
Pressure Measurements ◽  
Velocity Measurements ◽  
Flow Around A Cylinder

Velocity measurements in the laminar boundary layer around the forward portion of a circular cylinder are presented. These results are compared to Blasius’ theory for laminar flow around a cylinder using a free-stream velocity distribution obtained from static pressure measurements on the cylinder. Even though the flow is periodically unsteady as a result of vortex shedding from the cylinder, it is found that the agreement is excellent.

Experimental investigation into transonic flows over tandem cavities

2001 ◽  
Vol 105 (1045) ◽  
pp. 119-124 ◽  
Author(s):  
N. Taborda ◽  
D. Bray ◽  
K. Knowles
Keyword(s):  
Experimental Study ◽  
Experimental Investigation ◽  
Mach Number ◽  
Pressure Distribution ◽  
Static Pressure ◽  
Transonic Flows ◽  
Wide Range ◽  
Different Dimensions

AbstractAn experimental study was conducted to analyse the pressure distribution along the floor of a cavity, with and without the presence of an upstream tandem cavity, at a constant freestream Mach number of about 0-911. Measurements were made for single cavities and the results compared with those obtained in the presence of an upstream tandem cavity. This comparison was made over a wide range of geometries, covering open to closed classes of cavities with both identical and different dimensions for the two cavities. The effect of the spacing between the two cavities was also studied. The downstream cavity is shown to be significantly affected by the presence of an upstream cavity, with both the overall net static pressure and its gradient being affected, dependent upon the class of cavity geometry and spacing under consideration.

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