Flow characteristics in an expansion tunnel as inferred from velocity measurements

AIAA Journal ◽  
1977 ◽  
Vol 15 (9) ◽  
pp. 1364-1366
Author(s):  
Charles G. Miller ◽  
Wilfred J. Friesen
Keyword(s):  
Flow Characteristics ◽  
Velocity Measurements ◽  
Expansion Tunnel

scholarly journals Flow Characteristics of a 35° Inclined Turbulent Jet in a Crossflow on a Concave Surface

1992 ◽  
Author(s):  
Sang Woo Lee ◽  
Joon Sik Lee ◽  
Taik Sik Lee
Keyword(s):  
Near Field ◽  
Velocity Ratio ◽  
Three Dimensional ◽  
Flow Characteristics ◽  
Horseshoe Vortex ◽  
Concave Surface ◽  
Velocity Measurements ◽  
Downstream Region ◽  
Type Flow ◽  
Streamwise Pressure Gradient

The effect of the concave curvature on the flow of a streamwise 35° inclined jet issuing into a crossflow boundary layer has been investigated experimentally. Three-dimensional velocity measurements are performed in the near-field and some downstream region of jet exit by using a 5-hole directional probe. Since the main purpose is to investigate solely the effect of the concave curvature, the upper wall of the curved region is adjusted to minimize the effect of the streamwise pressure gradient. The results show that in the vicinity of the jet exit, the bound vortex dominates the flow structure, while in the far downstream region, the concave curvature plays an important role in converting the secondary flow into the Taylor-Görtler type flow. In addition, vortices rotating in the opposite direction with respect to the bound vortex is generated at both sides of the bound vortices, which stimulate the mixing of the jet and crossflow fluid. When the velocity ratio is large, the horseshoe vortex exists in the neighborhood of the jet exit, even though the strength is very weak compared with the bound vortex, however this horseshoe vortex may act as a kind of steady disturbance on the concave surface.

Comparison of Near Wake-Flow Structure Behind a Solid Cap With an Attached Bubble and a Solid Counterpart

2003 ◽  
Author(s):  
Hidekazu No ◽  
Michel Call ◽  
Akira T. Tokuhiro
Keyword(s):  
Flow Structure ◽  
Flow Characteristics ◽  
Wake Flow ◽  
Equivalent Diameter ◽  
Velocity Measurements ◽  
Near Wake ◽  
Downward Flow ◽  
Air Bubble ◽  
Square Channel ◽  
Image Velocimetry

An experimental study was conducted on the flow structure in the near-wake of a hollow cap with an air bubble attached underneath and a solid object possessing a bubble-like shape. The objective of the study was to elucidate distinguishing wake flow characteristics of the capped bubble relative to the solid. The experiment was performed in a square channel, 80×80mm2 in cross section. The bubble and solid were separately suspended in downward flow of purified water. Both the capped bubble and the solid were ellipsoidal in shape (the cap was shaped to represent the front of an ellipsoidal bubble) and had an approximate volume of 0.8ml. The Reynolds number for the flow, based on the objects’ equivalent diameter and average downward flow velocity (U = 25cm/s), was Re ≅ 2800. Velocity measurements were taken using Particle Image Velocimetry. The obtained velocity data were analyzed to deduce vorticity, turbulent kinetic energy, production, and Reynolds stress. Graphic and numerical comparisons between the two cases were made. The results to date are discussed.

Flow and Heat Transfer in the Space Between Two Corotating Disks in an Axisymmetric Enclosure

1989 ◽  
Vol 111 (3) ◽  
pp. 625-632 ◽  
Author(s):  
C. J. Chang ◽  
C. A. Schuler ◽  
J. A. C. Humphrey ◽  
R. Greif
Keyword(s):  
Heat Transfer ◽  
Flow Characteristics ◽  
Velocity Measurements ◽  
Flow And Heat Transfer ◽  
Gap Flow ◽  
Flow Reynolds Number ◽  
Improved Design ◽  
And Control ◽  
Gap Width ◽  
Disk Spacing

A numerical investigation was undertaken to characterize the laminar flow and heat transfer in axisymmetric coaxial corotating shrouded disk configurations. Attention was focused on calculation conditions favoring steady, stable, symmetric solutions of the conservation equations. The justification for this is based on velocity measurements obtained in a test section that matches the numerical configuration. Calculations were performed to investigate the dependence of the flow characteristics on disk angular velocity, disk spacing, and the disk–shroud gap width. Conditions involving a radial throughflow (blowing) and/or an axially directed disk–shroud gap flow were also predicted. In the region of the shroud the results show a strong sensitivity of the flow and heat transfer to variations in the flow Reynolds number (rotation) and Rossby number (blowing). By contrast, the flow was found to be less dependent on the disk spacing and the disk–shroud gap width for the conditions investigated. The introduction of an axially directed disk–shroud gap flow significantly alters the flow and heat transfer characteristics in the region between two disks. This finding is important for the improved design and control of corotating disk systems.

Dynamic Analysis of Airflow in Air-Jet Filling Insertion: Part II — Air Velocity Measurements

2002 ◽  
Author(s):  
Sabit Adanur ◽  
Sayavur I. Bakhtiyarov ◽  
Tacibaht Turel
Keyword(s):  
Dynamic Analysis ◽  
Air Flow ◽  
Flow Characteristics ◽  
Experimental System ◽  
Velocity Measurements ◽  
Air Velocity ◽  
Auburn University ◽  
Air Jet

Air-jet filling insertion is the most popular way of insertion systems in weaving. The heart of the air-jet filling insertion is the air flow, which provides the necessary propelling force for the yarn. In this work, the characteristics of airflow in air-jet filling insertion are discussed. The procedure and experimental system that is developed at Auburn University to measure the air flow characteristics is described.

Comparison of Flow Characteristics in Axial-Gap Seals for Close- and Wide-Spaced Turbine Stages

2007 ◽  
Author(s):  
Cheng-Zhang Wang ◽  
Bruce V. Johnson ◽  
Frederick De Jong ◽  
T. K. Vashist ◽  
Rajib Dutta
Keyword(s):  
Fluid Dynamics ◽  
Radial Velocity ◽  
Flow Characteristics ◽  
Leading Edge ◽  
The Other ◽  
State University ◽  
Arizona State University ◽  
Velocity Measurements ◽  
The University ◽  
Dynamics Analyses

3D unsteady computational fluid dynamics analyses were performed for both close-spaced and wide-spaced turbine stages with axial gap seals and a cavity. Turbine stages, with airfoil configurations similar to those previously studied at United Technologies Research Center (UTRC) and Arizona State University (ASU), were simulated for vane-blade spacing at 34 percent and 70 percent of the vane axial chord length, L. Three configurations were investigated, with the first one placing an axial gap rim seal at 17 percent L upstream of the blade for close-spaced stage, and the other two placing the axial gap seal at either 17 or 34 percent L upstream of the blade for the wide-spaced stage. The seal velocity ingestion characteristics were strongly dependent on axial location for the wide-spaced stage. The seals placed at equal distances upstream of the blade leading edge for the wide- and close-spaced stages had approximately the same average ingestion velocity characteristics. However, the ingestion velocity profiles for the wide-spaced stage were less influenced by vane wakes than for the close-spaced stage. The calculated variation of radial velocity in all gaps was consistent with previous tangential and radial velocity measurements in the seal gap measurements at the University of Aachen.

Effects of Gap Ratio on Flow Past a Square Cylinder

2014 ◽  
Author(s):  
Ebenezer E. Essel ◽  
Liam Sharkey ◽  
Mark F. Tachie
Keyword(s):  
Shear Stress ◽  
Reynolds Shear Stress ◽  
Flow Characteristics ◽  
Reynolds Stresses ◽  
Square Cylinder ◽  
Velocity Measurements ◽  
Freestream Velocity ◽  
Gap Ratio ◽  
Image Velocimetry ◽  
Bottom Face

The present study investigates the effect of gap ratio on the turbulent flow characteristics downstream of a square cylinder positioned in an open channel. Detailed velocity measurements were performed using a particle image velocimetry (PIV) system for gap ratios, G/h = 0.5 and 1, where G is the distance from the bottom face of the cylinder to the nearby wall and h is the cylinder height. Each set of experiments was conducted using a water depth of 65 mm and a Reynolds number of 2000 based on the height of the cylinder and the freestream velocity. Mean velocities, Reynolds stresses and Reynolds shear stress producing events of the quadrant decompositions were compared for the different gap ratios investigated. The results showed that as gap ratio decreased from 1 to 0.5 cylinder heights, the length of the separated region increased by 50%. Furthermore, the Reynolds stresses were found to decrease with decreasing gap ratio. Further downstream of the cylinder, the turbulent kinetic energy decreased, while the Reynolds shear stress increased for G/h = 0.5 compared to G/h = 1.

Flow Characteristics and Structure of 3D Turbulent Offset Jets

2014 ◽  
Author(s):  
B. Nyantekyi-Kwakye ◽  
S. Clark ◽  
M. F. Tachie ◽  
J. Malenchak ◽  
G. Muluye
Keyword(s):  
Reynolds Shear Stress ◽  
Three Dimensional ◽  
Symmetry Plane ◽  
Flow Characteristics ◽  
Velocity Measurements ◽  
Height Ratio ◽  
Mean Velocity ◽  
Image Velocimetry ◽  
Velocity Decay ◽  
Contour Plots

Three-dimensional turbulent offset jets were investigated with a particle image velocimetry (PIV) technique. Detailed velocity measurements for the flow were performed at an exit Reynolds number ranging from 8080–12080 for three offset height ratios of 0, 2 and 4. Profiles of the maximum mean velocity decay and wall-normal spread rates were observed to be sensitive to offset height ratio. Contour plots of mean velocity and turbulence kinetic energy exhibited dependence on offset height ratio. The reattachment lengths of the turbulent three-dimensional offset jets were observed to increase with offset height ratio. The results within the symmetry plane revealed that the production of Reynolds shear stress was not significantly enhanced by offset height ratio further downstream.

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