Electrohydrodynamic Airflow Control Along a Flat Plate by a DC Surface Corona Discharge - Velocity Profile and Wall Pressure Measurements

2002 ◽  
Author(s):  
Luc Leger ◽  
Eric Moreau ◽  
Gérard Touchard
Keyword(s):  
Velocity Profile ◽  
Flat Plate ◽  
Corona Discharge ◽  
Wall Pressure ◽  
Pressure Measurements ◽  
Discharge Velocity

Calculation of tunnel wall interference from wall-pressure measurements

1988 ◽  
Vol 92 (911) ◽  
pp. 36-53 ◽  
Author(s):  
P. R. Ashill ◽  
R. F. A. Keating
Keyword(s):  
Experimental Evaluation ◽  
Solid Wall ◽  
Wall Pressure ◽  
Wind Tunnels ◽  
Pressure Measurements ◽  
Complex Flows ◽  
Tunnel Wall ◽  
Model Flow ◽  
Good Agreement

Summary A method is described for calculating wall interference in solid-wall wind tunnels from measurements of static pressures at the walls. Since it does not require a simulation of the model flow, the technique is particularly suited to determining wall interference for complex flows such as those over VSTOL aircraft, helicopters and bluff shapes (e.g. cars and trucks). An experimental evaluation shows that the method gives wall-induced velocities which are in good agreement with those of existing methods in cases where these techniques are valid, and illustrates its effectiveness for inclined jets which are not readily modelled.

Interaction Between the Underwater Explosion Bubble and the Structure

2008 ◽  
Author(s):  
A. M. Zhang ◽  
X. L. Yao ◽  
D. Y. Shi ◽  
J. Li
Keyword(s):  
Free Surface ◽  
Flat Plate ◽  
Dynamic Characteristics ◽  
Potential Flow ◽  
Underwater Explosion ◽  
Wall Pressure ◽  
Severe Damage ◽  
Plastic Structure ◽  
Pressure Peak ◽  
Great Damage

Based on the potential-flow assumption, BEM is applied to simulate the dynamic characteristics of underwater explosion bubble near boundaries and solve the interaction of bubble and elastic-plastic structure by coupling with FEM. A complete 3D program of underwater bubble analysis (UBA) is developed and the calculated error is within 10%. With this program, flat plate, cylinder and other simple structures are analyzed; the damages caused by retarded flow, pulsating pressure and jet and other loads on the structures are calculated, including different cases with free surface or without free surface. Results show that bubbles can cause great damage, and the specific cases can even cause greater damage. From the wall pressure and the stress curves of typical elements on the structure, it can be seen that the pressure peak occurs when the bubble collapses, which proves that the pressures caused by the bubble’s collapse and jet can result in great structure’s severe damage. It can provide reference for the research on the dynamic characteristics. The research in this paper aims to provide references for the correlated research on the dynamics of the underwater bubble.

Pressure and velocity measurements of an incompressible moderate Reynolds number jet interacting with a tangential flat plate

2015 ◽  
Vol 770 ◽  
pp. 247-272 ◽  
Author(s):  
A. Di Marco ◽  
M. Mancinelli ◽  
R. Camussi
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Scaling Laws ◽  
Pressure Fluctuations ◽  
Wall Pressure ◽  
Theoretical Modelling ◽  
Wall Pressure Fluctuations ◽  
Moderate Reynolds Number ◽  
The Mean ◽  
Pressure And Velocity Measurements

The statistical properties of wall pressure fluctuations generated on a rigid flat plate by a tangential incompressible single stream jet are investigated experimentally. The study is carried out at moderate Reynolds number and for different distances between the nozzle axis and the flat plate. The overall aerodynamic behaviour is described through hot wire anemometer measurements, providing the effect of the plate on the mean and fluctuating velocity. The pressure field acting on the flat plate was measured by cavity-mounted microphones, providing point-wise pressure signals in the stream-wise and span-wise directions. Statistics of the wall pressure fluctuations are determined in terms of time-domain and Fourier-domain quantities and a parametric analysis is conducted in terms of the main geometrical length scales. Possible scaling laws of auto-spectra and coherence functions are presented and implications for theoretical modelling are discussed.

Unsteady Wall Pressure Measurements In An Outflow Butterfly Valve Using Remote Microphone Probes

2016 ◽  
Author(s):  
Aurelien Marsan ◽  
Marlene Sanjose ◽  
Yann Pasco ◽  
Stephane Moreau ◽  
Martin Brouillette
Keyword(s):  
Wall Pressure ◽  
Pressure Measurements ◽  
Butterfly Valve

External Forced Convection Enhancement Using a Corona Discharge

2007 ◽  
Author(s):  
David B. Go ◽  
Raul A. Maturana ◽  
Timothy S. Fisher ◽  
Suresh V. Garimella
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Corona Discharge ◽  
Flow Direction ◽  
Steel Wire ◽  
Experimental Studies ◽  
Local Heat Transfer ◽  
Bulk Flow ◽  
Electrode Pair ◽  
Transfer Coefficients

An ionic wind is formed when air ions generated by a corona discharge are accelerated by an electric field and exchange momentum with neutral air molecules, causing air flow. Because ionic winds can generate flow with no moving parts, they offer an attractive method for enhancing the heat transfer from a surface that would otherwise only be cooled by natural convection and/or radiation. In the presence of an external, flat plate flow, ionic winds distort the boundary layer such that local heat transfer is enhanced at the wall, and recent work has suggested that integrating such devices can be useful for cooling electronic components locally. In this work, corona discharges are generated between a steel wire and copper tape electrode pair on a flat plate, perpendicular to the bulk flow direction such that the discharge is in the direction of the bulk flow. The corona discharge current is characterized, and a corona glow and spark discharge are visualized. Experimental studies of the heat transfer from a heated flat plate are conducted using an infrared camera which indicated both upstream and downstream cooling along the entire length of the wire. Heat transfer coefficients are increased by more than 200% above those obtained from bulk flow alone and are correlated to the fourth root of the corona current. Preliminary parametric studies demonstrate the influence of the electrode-pair configuration on the cooling enhancement and suggest improved geometric designs.

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.

Some Experiments on the Reattachment of a Laminar Boundary Layer Separating From a Rearward Facing Step on a Flat Plate Aerofoil

1960 ◽  
Vol 64 (599) ◽  
pp. 668-672 ◽  
Author(s):  
T. W. F. Moore
Keyword(s):  
Boundary Layer ◽  
Liquid Film ◽  
Flat Plate ◽  
Laminar Boundary Layer ◽  
Reverse Flow ◽  
Leading Edge ◽  
Reynolds Numbers ◽  
Pressure Measurements ◽  
Flow Vortex

Summary:The results of experiments on the reattachment of a laminar boundary layer, separating from a rearward facing step in a flat plate aerofoil, are correlated with the properties of the short leading edge bubble which forms on thin aerofoils near the stall.The experiments, comprising pressure measurements, Pitot explorations, liquid film and smoke studies, indicate that for all Reynolds numbers above the value given by the Owen-KIanfer criterion the reattachment is turbulent behind a stationary air reverse flow vortex bubble. It is also found that the reattachment is laminar for Reynolds numbers below the critical, which further supports Crabtree's interpretation of the Owen-KIanfer criterion in terms of the condition for the growth of turbulent bursts.

On strong blowing into an incompressible airstream

1973 ◽  
Vol 60 (2) ◽  
pp. 241-255 ◽  
Author(s):  
F. T. Smith
Keyword(s):  
Experimental Study ◽  
Flow Field ◽  
Velocity Profile ◽  
Air Injection ◽  
Relative Mass ◽  
Pressure Measurements ◽  
Flow Rates ◽  
Mass Flow Rates ◽  
Strong Injection ◽  
Steady Laminar

An experimental study of distributed air-injection from a porous section of a flat plate into a uniform incompressible airflow is described. The relative mass flow rates of the injection varied between 0·008 and 0·053 (strong injection) and the blowing was fairly uniformly distributed. In the resulting flow field, which was predominantly laminar except near the dividing streamline, where unsteadiness prevailed, velocity profile and pressure measurements were taken and the position of the dividing streamline thereby estimated. Overall the results agree fairly well with the steady laminar theory for strong normal blowing, outlined in §2, although for the strongest blow some signs of separation some way upstream of the blow are apparent.

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