Velocity measurements in a high-Reynolds-number, momentum-conserving, axisymmetric, turbulent jet

1994 ◽  
Vol 258 ◽  
pp. 31-75 ◽  
Author(s):  
Hussein J. Hussein ◽  
Steven P. Capp ◽  
William K. George
Keyword(s):  
Reynolds Number ◽  
Laser Doppler Anemometry ◽  
Cross Flow ◽  
Hot Wire ◽  
Velocity Measurements ◽  
Third Order ◽  
Burst Mode ◽  
High Turbulence ◽  
High Reynolds ◽  
Velocity Moments

The turbulent flow resulting from a top-hat jet exhausting into a large room was investigated. The Reynolds number based on exit conditions was approximately 105. Velocity moments to third order were obtained using flying and stationary hot-wire and burst-mode laser-Doppler anemometry (LDA) techniques. The entire room was fully seeded for the LDA measurements. The measurements are shown to satisfy the differential and integral momentum equations for a round jet in an infinite environment.The results differ substantially from those reported by some earlier investigators, both in the level and shape of the profiles. These differences are attributed to the smaller enclosures used in the earlier works and the recirculation within them. Also, the flying hot-wire and burst-mode LDA measurements made here differ from the stationary wire measurements, especially the higher moments and away from the flow centreline. These differences are attributed to the cross-flow and rectification errors on the latter at the high turbulence intensities present in this flow (30% minimum at centreline). The measurements are used, together with recent dissipation measurements, to compute the energy balance for the jet, and an attempt is made to estimate the pressure-velocity and pressure-strain rate correlations.

K-1229 Turbulence-Induced Fluid Dynamic Forces Acting on Cross-Shaped Tube Bundle in Cross Flow : Part 2 : Measurement in the High Reynolds Number

2001 ◽  
Vol V.01.1 (0) ◽  
pp. 139-140
Author(s):  
Takashi NISHIHARA ◽  
Nobukazu TANAKA ◽  
Fumio INADA ◽  
Akira YASUO ◽  
Shinichi KAWAMURA ◽  
...  
Keyword(s):  
Reynolds Number ◽  
High Reynolds Number ◽  
Tube Bundle ◽  
Fluid Dynamic ◽  
Cross Flow ◽  
Shaped Tube ◽  
Dynamic Forces ◽  
Flow Part ◽  
High Reynolds

Effect of Longitudinal Vortex on Boundary Layer State and Separation on NACA Symmetric Foil

2010 ◽  
Author(s):  
Sebastien Prothin ◽  
Henda Djeridi ◽  
Jean-Yves Billard
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Shape Factor ◽  
Base Flow ◽  
Vortex Generators ◽  
Longitudinal Vortex ◽  
Velocity Measurements ◽  
Number Range ◽  
Fluid Displacement ◽  
High Reynolds

Vortex generators have been widely used in aerodynamics to control the separation of boundary layers. In such application (Angele and Muhammad, 2005) vortex generators are embedded in the boundary layer and the vortex height, with regards to the wall, is of the boundary layer thickness. The objective of this configuration is obviously far from being the effects of a single longitudinal vortex (generated upstream by an elliptical plan form profile) on the turbulent boundary layer shape over a Naca0015 symmetric foil at different incidences at high Reynolds number 5 105. The vortex is situated outside the boundary layer (ten times the BL thickness over the wall) taking into account the small value of the thickness in our hydrodynamic application. Obviously, this situation is optimum as the vortex delays separation and increases the maximum lift but introduces drag penalty at small incidence. This is nevertheless frequently encountered in hydrodynamic applications (hub vortex upstream of a rudder) and of interest. To point out the mechanism of the boundary layer manipulation, both global efforts using gauge balance and velocity measurements using LDV and PIV have been performed and compared with and without vortex. The base flow is an APG boundary layer characterized by a predominant wake area. Effect of the vortex is analyzed via the shape factor both in inflow and outflow regions. The longitudinal vortex suppress the hysteretic loop classically described in this Reynolds number range (Djeridi et al., 2009) but an increase of the drag is observed in the range of incidence just before stall. Velocity measurements indicated that, for incidences near the stall appearance, the shape factor is decreased both in the inflow and in the outflow regions. Even for large incidences, in the inflow region the value of the shape factor is equivalent to the one found in the turbulent BL over a flat plate. In this region the vortex modifies the equilibrium state of the BL as attested by the Clauser parameter. Even for large distances between the vortex and the wall, the ability of the vortex to suppress the detachment of the BL is observed on the evolution of the backflow coefficient. This effect is greater pronounced in inflow area near the trailing edge region where the flow is locally reattached due to the high momentum fluid displacement.

High spatial range velocity measurements in a high Reynolds number turbulent boundary layer

2014 ◽  
Vol 26 (2) ◽  
pp. 025117 ◽  
Author(s):  
C. M. de Silva ◽  
E. P. Gnanamanickam ◽  
C. Atkinson ◽  
N. A. Buchmann ◽  
N. Hutchins ◽  
...  
Keyword(s):  
Boundary Layer ◽  
Reynolds Number ◽  
Turbulent Boundary Layer ◽  
High Reynolds Number ◽  
Velocity Measurements ◽  
Spatial Range ◽  
High Reynolds

scholarly journals Trajectory of a synthetic jet issuing into high-Reynolds-number turbulent boundary layers

2018 ◽  
Vol 856 ◽  
pp. 531-551 ◽  
Author(s):  
Tim Berk ◽  
Nicholas Hutchins ◽  
Ivan Marusic ◽  
Bharathram Ganapathisubramani
Keyword(s):  
Reynolds Number ◽  
Boundary Layers ◽  
High Reynolds Number ◽  
Velocity Ratio ◽  
Cross Flow ◽  
Turbulent Boundary Layers ◽  
Synthetic Jet ◽  
Actuation Frequency ◽  
The Cross ◽  
High Reynolds

Synthetic jets are zero-net-mass-flux actuators that can be used in a range of flow control applications. For some applications, the scaling of the trajectory of the jet with actuation and cross-flow parameters is important. This scaling is investigated for changes in the friction Reynolds number, changes in the velocity ratio (defined as the ratio between the mean jet blowing velocity and the free-stream velocity) and changes in the actuation frequency of the jet. A distinctive aspect of this study is the high-Reynolds-number turbulent boundary layers (up to $Re_{\unicode[STIX]{x1D70F}}=12\,800$) of the cross-flow. To our knowledge, this is the first study to investigate the effect of the friction Reynolds number of the cross-flow on the trajectory of an (unsteady) jet, as well as the first study to systematically investigate the scaling of the trajectory with actuation frequency. A broad range of parameters is varied (rather than an in-depth investigation of a single parameter) and the results of this study are meant to indicate the relative importance of each parameter rather than the exact influence on the trajectory. Within the range of parameters explored, the critical ones are found to be the velocity ratio as well as a non-dimensional frequency based on the jet actuation frequency, the cross-flow velocity and the jet dimensions. The Reynolds number of the boundary layer is shown to have only a small effect on the trajectory. An expression for the trajectory of the jet is derived from the data, which (in the limit) is consistent with known expressions for the trajectory of a steady jet in a cross-flow.

LDA Measurements in Plane Turbulent Jets

1985 ◽  
Vol 107 (2) ◽  
pp. 264-271 ◽  
Author(s):  
B. R. Ramaprian ◽  
M. S. Chandrasekhara
Keyword(s):  
Laser Doppler Anemometry ◽  
Turbulent Jets ◽  
Fast Response ◽  
Independent Data ◽  
Hot Wire ◽  
Velocity Measurements ◽  
Effective Technique ◽  
Two Component ◽  
The Mean ◽  
Resistance Thermometry

Measurements on the mean and most of the significant turbulent properties of plane isothermal and heated (but essentially “nonbouyant”) jets are reported. The velocity measurements were made using two-component, frequency-shifted Laser Doppler Anemometry (LDA) and the temperature measurements were made using fast-response resistance thermometry. A simple but effective technique was developed for obtaining accurate velocity measurements from the LDA in a nonisothermal environment. These measurements, some of which are the first of their kind, provide an independent data base with which to compare existing hot-wire data on jets. The LDA measurements indicate lower turbulence intensities and lower turbulent fluxes compared to the hot-wire data.

Velocity and Turbulence Fields in Pipe Entrance Regions in the Presence of Cross Flows

1986 ◽  
Vol 108 (3) ◽  
pp. 498-503 ◽  
Author(s):  
S. Lloyd ◽  
A. Brown
Keyword(s):  
Experimental Investigation ◽  
Reynolds Number ◽  
Cross Flow ◽  
Entrance Region ◽  
Pipe Diameter ◽  
Circular Pipe ◽  
Working Fluid ◽  
Hot Wire

This paper reports on an experimental investigation into the velocity and turbulence fields in the entrance region of a circular pipe with cross flow at the entry. The pipe entry is a sharp square-edged type with air as the working fluid and measurements are made over the region 0<X/D<21. Observations are presented for a range of cross flows with a maximum Reynolds number, based on pipe diameter, of 64,000. The hot-wire anemometer measurements show a separated nonaxisymmetric flow at entry followed by a skewed flow which progressively smooths out with distance along the pipe.

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