Blockage Corrections for Rectangular Flat Plates Mounted in an Open Jet Wind Tunnel

1983 ◽  
Vol 197 (4) ◽  
pp. 259-263 ◽  
Author(s):  
A T Sayers ◽  
D R Ball
Keyword(s):  
Wind Tunnel ◽  
Flat Plate ◽  
Wind Velocity ◽  
Experimental Technique ◽  
Flow Direction ◽  
The Body ◽  
Wind Tunnels ◽  
Flat Plates ◽  
Projected Area

The correction that must be applied to the upstream wind velocity, when a rectangular flat plate normal to the flow direction is placed in an open jet wind tunnel, is determined and is found to be at all times equal to or greater than unity. It is also found to be dependent upon the distance of the body from the tunnel outlet, and the projected area of the body. Comparisons with previous work carried out in closed wind tunnels are made to confirm the experimental technique used.

Angular Dependency on Film Boiling Heat Transfer From Relatively Long Inclined Flat Plates

2013 ◽  
Vol 135 (12) ◽  
Author(s):  
Chan Soo Kim ◽  
Kune Y. Suh
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Boiling Heat Transfer ◽  
Flow Direction ◽  
Film Boiling ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Heat Transfer Coefficients ◽  
Inclination Angles ◽  
Angular Dependency

The effect of inclination angle of the downward facing flat plate on the interfacial wavy motion is investigated utilizing the water quenching test apparatus downward ebullient laminar transition apparatus flat surface (DELTA-FS) in a quasi-steady state. Film boiling heat transfer coefficients are obtained on the relatively long surface in the flow direction. Interfacial velocities at the various inclination angles and wall superheat conditions are determined through the analysis of the visualized continuous snapshots with 1000 fps. Visualization of the vapor film reveals that the interfacial wavelength increases and the interfacial velocity decreases as the flat plate moves from the vertical to downward facing locations. A new semi-empirical correlation is developed from the measured heat transfer coefficients and interfacial velocities. The correlation shows good agreement with the previous water test results on vertical plates. In the case of the previous other fluid experimental results on the vertical plates, the correlation overpredicts the film boiling heat transfer coefficients at the experimental condition.

Resistance of Two Inclined Parallel Flat Plates Placed in Tandem on a Stream-Wise Flat Plate in Two-Dimensional Flow

1993 ◽  
Vol 207 (6) ◽  
pp. 393-397
Author(s):  
R C Mehta ◽  
C R Rao ◽  
Y N Dubey
Keyword(s):  
Reynolds Number ◽  
Drag Coefficient ◽  
Flat Plate ◽  
Flow Direction ◽  
Considerable Extent ◽  
Appreciable Effect ◽  
Two Dimensional ◽  
Flat Plates ◽  
Dimensional Flow ◽  
Two Dimensional Flow

The paper presents the results of an experimental study on the drag coefficient of two inclined parallel flat plates, placed on a stream-wise flat plate, in tandem, in two-dimensional flow. The effects on the drag coefficient of Reynolds number, the inclination of the plates to the flow direction and the relative spacing between plates were studied. It is observed that, while the Reynolds number has no appreciable effect, the other parameters influence the drag coefficient to a considerable extent. The results are corrected for blockage effect and comparisons are made with the data collected by other investigators.

Wind-Tunnel Screens: Flow Instability and its Effect on Aerofoil Boundary Layers

1964 ◽  
Vol 68 (639) ◽  
pp. 198-198 ◽  
Author(s):  
P. Bradshaw
Keyword(s):  
Boundary Layer ◽  
Wind Tunnel ◽  
Layer Thickness ◽  
Boundary Layers ◽  
Boundary Layer Thickness ◽  
Flow Instability ◽  
Flow Direction ◽  
Flat Plates ◽  
Mixing Processes ◽  
Flow Through

Morgan has described a spatial instability in the flow through screens or grids of small open-area ratio. Head and Rechenberg and others have observed large span-wise variations in the thickness and shear stress of nominally two-dimensional boundary layers on flat plates and aerofoils in wind tunnels. It now appears that these spanwise variations are caused by the instability of flow through the screens. The jets of air issuing from the pores of the screen attempt to entrain more air by the usual mixing processes, but can only entrain it from each other, so that groups of jets coalesce in rather random (steady) patterns determined by small irregularities in the weave. The resulting variations in axial velocity are virtually eliminated by the wind tunnel contraction, but variations in flow direction are not so greatly reduced: a theoretical analysis shows that the observed variations of boundary-layer thickness, which often reach ± 10 per cent of the mean, can be produced by directional variations in the working section of the order of ± 1/20 deg, with a spanwise wavelength of the same order as the boundary-layer thickness.

scholarly journals Sensitivity Investigation on the Pressure Coefficients Non-Dimensionalization

2021 ◽  
Vol 6 (4) ◽  
pp. 53
Author(s):  
Fabio Rizzo
Keyword(s):  
Wind Tunnel ◽  
Wind Velocity ◽  
Time History ◽  
Wind Tunnels ◽  
Pressure Coefficients ◽  
Box Section ◽  
Large Structures ◽  
Suspended Bridge

The scaling of large structures to investigate their aerodynamics in wind tunnels is a common and robust procedure to estimate important magnitudes, including pressure coefficients. Different aspects can affect the estimation of pressure coefficients; four examples are the non-dimensionalization, blockage, non-stationarity, and non-Gaussianity of the wind tunnel velocity. This paper shows the variability of pressure coefficients due to these four aspects for the case study of a closed box section of a suspended bridge. It was estimated that the pressure coefficients of similar pressure taps vary significantly due to different sets of wind velocity time history used to non-dimensionalize the wind tunnel pressures. In addition, the stationarity of the wind velocity process was not confirmed for all wind velocity sets and the non-Gaussianity of the wind velocity time history was confirmed.

The prospect ahead

1971 ◽  
Vol 269 (1199) ◽  
pp. 545-554
Keyword(s):  
Wind Tunnel ◽  
Bluff Body ◽  
Wind Tunnel Test ◽  
Accurate Solution ◽  
The Body ◽  
Wind Tunnels ◽  
Dual Approach ◽  
Architectural Models ◽  
Wind Pressures ◽  
Large Wind

The exacting nature of the problems of architectural aerodynamics and some of the difficulties of obtaining an accurate solution to them from laboratory experiments are described. Among the latter is the uncertainty associated with scale effect, which requires for its resolution more observations of the flow patterns about, and measurements of the wind pressures on, actual buildings and structures. The possibility of constructing a special wind tunnel is also mentioned. A dual approach to aerodynamic research is advocated: such that work in large wind tunnels, with complicated architectural models and elaborate simulation of the atmospheric wind, proceed in parallel with investigations on a simpler scale. The latter should concentrate on fundamental aspects of bluff body flows; particularly their unsteady components, their interaction with shear and turbulence in the approaching stream, as well as their dependence on the shape of the body, on any vibration it may exhibit and on its interference with neighbouring bodies. Examples are given of some of the subtle and surprising features of such flows. The architect is invited to specify the accuracy he requires of aerodynamic data and is urged to regard the wind-tunnel test, with full representation of the atmospheric wind and its turbulent structure, as a routine element in the design process.

scholarly journals Turbulence investigation in the VTI’s experimental aerodynamics laboratory

2017 ◽  
Vol 21 (suppl. 3) ◽  
pp. 629-647 ◽  
Author(s):  
Slavica Ristic ◽  
Suzana Linic ◽  
Marija Samardzic
Keyword(s):  
Wind Tunnel ◽  
Test Section ◽  
Flow Direction ◽  
Technical Information ◽  
Low Flow ◽  
Wind Tunnels ◽  
Main Requirement ◽  
Measurement Results ◽  
Experimental Aerodynamics ◽  
Flow Quality

Wind tunnels are the aerodynamic laboratories which task is to enable high quality and stabile airflow in controlled volume, a test section, during run time, in order to study the effects of streaming around various aeronautical or nonaeronautical models (airfoils and bluff bodies with complex motorized or robotic constructions). The main requirement that leads to quality and reliable measurement results is a high flow quality in the test section: uniformity of the velocity and pressure fields along and across the test section, low turbulence level and low flow direction angularities or swirling. The knowledge of low parameters enables the exchange of the scientific and technical information, comparison of the experimental results from different wind tunnels and data scaling of the model to the real scale. The turbulence intensity TI significantly affects the wind tunnel results and reduction of turbulence is of the highest importance for the quality measurements. This paper presents the Experimental Aerodynamics Laboratory of the VTI in Belgrade, the equipment and methods of turbulence measurements in the test section stream and around different test models. Wind tunnel facilities maintain equipment and devices for sampling, acquisition and data reduction for various test types, from forces and moment measurements, over the pressure distribution measurements to the advanced measurements, followed with the appropriate flow visualization techniques. The modern instrumentation enables determine flow quality and its influence on tests and measurement results of static and dynamic model characteristics.

scholarly journals DESAIN ALAT UJI NOSEL DENGAN MENGGUNAKAN PRINSIP TEROWONGAN ANGIN SUPERSONIK

2012 ◽  
Vol 9 (1) ◽  
Author(s):  
Bagus H. Jihad ◽  
Dedi Priadi
Keyword(s):  
Wind Tunnel ◽  
Internal Flow ◽  
The Body ◽  
Wind Tunnels ◽  
Testing System ◽  
Nozzle Design ◽  
Flow Conditions ◽  
Special Software ◽  
Run Time ◽  
Effective Speed

 The accuracy of nozzle design can be improved by validation. Two methods of validation is software or hardware application. The software can be either CFD software or special software for the nozzle design, such as NOZZLE ® or Aerospike ®. The limitations of CFD software is on unsteady flow conditions. while the limitations of special software is the obscurity of assumptions used. Therefore, the flow validation experimental is important to be implemented. Lapan has three units of wind tunnels, namely subsonic, transonic and supersonic. They have the capability to measure the external flow of the body. While the nozzle design purpose is mostly to investigate the internal flow of the nozzle. Therefore, the nozzle flow testing system which is called a mini wind tunnel has been designed.This wind tunnel is designed to have speed of Mach 2.4, but the effective speed of 2 Mach. By using a calculation we obtain the run time of 46 seconds. If we assume the pressure drop is 40%, then actually the run time is 28 seconds.Keyword:Windtunnel, Nozzle, Supersonic, Run-time, Schlieren

Film Boiling on Downward Facing Flat Plates With Varying Inclination Angles

2005 ◽  
Author(s):  
Chan S. Kim ◽  
Mong J. Yu ◽  
Kune Y. Suh ◽  
Joy L. Rempe ◽  
F. Bill Cheung ◽  
...  
Keyword(s):  
Heat Transfer ◽  
Flat Plate ◽  
Flat Surface ◽  
Flow Direction ◽  
Film Boiling ◽  
Transfer Coefficients ◽  
Flat Plates ◽  
Heat Transfer Coefficients ◽  
Inclination Angles ◽  
Water Test

The effect of inclination angle of the downward facing flat plate on the interfacial wavy motion is investigated utilizing the water test apparatus DELTA FS (Downward Ebullient Laminar Transition Apparatus Flat Surface) in a quasi-steady state. Film boiling heat transfer coefficients are obtained on the relatively long surface in the flow direction. The measured heat transfer coefficients are compared with those predicted by the laminar film boiling and interfacial wavy film boiling correlations at the same experimental condition. Visualization of the vapor film revealed that the interfacial wavelength decreases as the flat plate moves from the vertical to downward facing locations.

scholarly journals Experimental Investigation on the Effect of Angles of Attack to the Flutter Speed of a Flat Plate in Axial Flow

2021 ◽  
Vol 21 (2) ◽  
pp. 111-116
Author(s):  
I Putu Gede Sopan Rahtika ◽  
◽  
I Made Suarta ◽  
I Komang Rusmariadi ◽  
Putu Wijaya Sunu ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Wind Tunnel ◽  
Flat Plate ◽  
Experimental Research ◽  
Relative Position ◽  
Air Flow ◽  
Axial Flow ◽  
Flat Plates ◽  
Flutter Speed ◽  
Subsonic Wind Tunnel

The application of flat plates to the field of wind harvesting requires a lot of research toward the understanding of the flutter behavior of the plates. There are shortages of articles that discuss the effect of varying the angles of attack to the flutter speed of a flat plate. This research aims to conduct a basic experimental research on the effect of relative position of a thin-flat plates to the direction of the air flow to its flutter speed. In this study, a thin-flat plate was placed in a subsonic wind tunnel to test its flutter speed. The position of the plate was varied in various angles of attack. The effect of the angles of attack to the flutter speed was observed.

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