Passive Control of the Two-Dimensional Jet Using a Rectangular Notch

2002 ◽  
Author(s):  
Shigetaka Fujita ◽  
Takashi Harima ◽  
Hideo Osaka
Keyword(s):  
Passive Control ◽  
Core Region ◽  
Turbulent Jet ◽  
Upstream Region ◽  
Entrainment Rate ◽  
Two Dimensional ◽  
Flow Properties ◽  
Potential Core ◽  
The Mean ◽  
Rectangular Notch

The mean and turbulent flow properties of turbulent jet issuing from a quasi two-dimensional (2-D) nozzle with a rectangular notch (aspect ratio: AR=12.5) perpendicular to the two-dimensional nozzle at the midspan, have been measured. The exit Reynolds number was kept constant 13000. The aim of this study is to examine the effects of the rectangular notch on the mean and turbulent flowfields of the two-dimensional jet, and to clarify a possibility of a passive control of the two-dimensional jet using a rectangular notch. From the experiments, it was revealed that the potential core region existed until the section of x/d=25. In the upstream region, the entrainment rate was smaller than that of the two-dimensional jet due to the inward secondary flow on the y and z axes. Furthermore, the streamwise development of the turbulent intensity was delayed.

A vortex-street model of the flow in the similarity region of a two-dimensional free turbulent jet

1982 ◽  
Vol 123 ◽  
pp. 523-535 ◽  
Author(s):  
J. W. Oler ◽  
V. W. Goldschmidt
Keyword(s):  
Experimental Data ◽  
Reynolds Stress ◽  
Turbulent Jet ◽  
Vortex Street ◽  
Two Dimensional ◽  
Mean Flow ◽  
Mean Velocity ◽  
The Core ◽  
The Mean ◽  
Similarity Relationships

The mean-velocity profiles and entrainment rates in the similarity region of a two-dimensional jet are generated by a simple superposition of Rankine vortices arranged to represent a vortex street. The spacings between the vortex centres, their two-dimensional offsets from the centreline, as well as the core radii and circulation strengths, are all governed by similarity relationships and based upon experimental data.Major details of the mean flow field such as the axial and lateral mean-velocity components and the magnitude of the Reynolds stress are properly determined by the model. The sign of the Reynolds stress is, however, not properly predicted.

Reattachment of a Two-Dimensional, Incompressible Jet to an Adjacent Flat Plate

1960 ◽  
Vol 11 (3) ◽  
pp. 201-232 ◽  
Author(s):  
C. Bourque ◽  
B. G. Newman
Keyword(s):  
Reynolds Number ◽  
Flat Plate ◽  
Separation Bubble ◽  
Volume Flow ◽  
Turbulent Jet ◽  
Two Dimensional ◽  
General Investigation ◽  
Mean Pressure ◽  
The Mean ◽  
Coandǎ Effect

SummaryAs part of a general investigation into Coanda effect, a study has been made of the reattachment of a two-dimensional, incompressible, turbulent jet to an adjacent, inclined, flat plate. The jet separates from the boundaries at the slot lips and reattaches to the plate downstream, a phenomenon which is associated with the lowering of the pressure between the jet and the plate accompanying the entrainment of fluid there. It is found that the flow becomes independent of both the length of the plate and the Reynolds number when these parameters are sufficiently large: the flow, scaled with respect to the width of the slot, is then uniquely determined by the plate inclination. Two approximate theories are developed for the mean pressure within the separation bubble, the position of reattachment and the increase in volume flow from the slot: the agreement with experiment is fairly satisfactory. These theories are a development of Dodds's analysis for the reattachment of a jet to a plate offset from, and parallel to, the axis of the slot and, for the purpose of comparison, a limited study is also made of this flow.

scholarly journals 520 Manipulation of two-dimensional turbulent jet using multiple rectangular notches : Mean flow properties

2009 ◽  
Vol 2009.47 (0) ◽  
pp. 175-176
Author(s):  
Shigetaka FUJITA ◽  
Takashi HARIMA ◽  
Takahiro FUJIMOTO ◽  
Hideo OSAKA
Keyword(s):  
Turbulent Jet ◽  
Two Dimensional ◽  
Mean Flow ◽  
Flow Properties

Interaction of an Acoustic Disturbance and a Two-Dimensional Turbulent Jet: Experimental Data

1983 ◽  
Vol 105 (2) ◽  
pp. 134-139 ◽  
Author(s):  
F. O. Thomas ◽  
V. W. Goldschmidt
Keyword(s):  
Turbulent Jet ◽  
Vortical Flow ◽  
Energy Spectra ◽  
Flow Structures ◽  
Two Dimensional ◽  
Frequency Range ◽  
Initial Region ◽  
Acoustic Disturbance ◽  
Turbulent Flow Structure ◽  
The Mean

An experimental study was performed to determine the effects a periodic acoustic disturbance had upon a two-dimensional turbulent jet in both the initial and similarity regions. Correlation and energy spectra measurements in the initial region indicate that acoustic forcing within a certain frequency range is capable of restructuring the flow in this region. In particular, these measurements suggest the presence of vortical flow structures arranged symmetrically with respect to the jet centerline. Measurements of the mean and turbulent flow structure in the similarity region of the jet indicate strong acoustically induced effects. Evidence suggests that the interaction effects observed in the similarity region are intimately related to those in the initial region.

The Swirling Turbulent Jet

1972 ◽  
Vol 94 (4) ◽  
pp. 739-747 ◽  
Author(s):  
B. D. Pratte ◽  
J. F. Keffer
Keyword(s):  
Experimental Investigation ◽  
Static Pressure ◽  
Decay Rates ◽  
Turbulent Jet ◽  
Entrainment Rate ◽  
Self Similarity ◽  
Free Jet ◽  
Swirling Jet ◽  
Self Similar ◽  
The Mean

An experimental investigation has been made of a swirling jet having a moderate ratio of swirling to axial momentum. Measurements showed that the flow achieved a self-similarity for the mean velocities rather quickly while the normal turbulent intensities reached a self-similar state after a longer period of jet development. Conservation arguments were used to predict streamwise decay rates for the mean quantities. The analysis showed that the maximum axial and swirling velocity components should vary asymptotically as (x − x0)−1 and (x − x0)−2, respectively. The experimental results confirmed this satisfactorily. The minimum static pressure was predicted to vary at a rate proportional to (x − x0)−4. Measurements indicated, however, that the relation was closer to (x − x0)−2. Better agreement with the data was achieved when the analytical expression was adjusted for the effect of the turbulence terms. The entrainment rate and angle of spread for the swirling jet were found to be nearly twice that of the non-swirling free jet.

On the development of noise-producing large-scale wavelike eddies in a plane turbulent jet

1975 ◽  
Vol 70 (2) ◽  
pp. 353-368 ◽  
Author(s):  
Lee-Or Merkine ◽  
J. T. C. Liu
Keyword(s):  
Boundary Layer ◽  
Boundary Layer Thickness ◽  
Large Scale ◽  
Frequency Parameter ◽  
Turbulent Jet ◽  
Two Dimensional ◽  
Fine Scale ◽  
Mean Flow ◽  
Potential Core

In this paper we study the development of large-scale wavelike eddies in a two-dimensional turbulent jet, extending earlier work on the mixing region (Liu 1974). The basic mean flow develops from one of mixing-region type with an initially specified boundary-layer thickness into a fully developed jet. This study brings out the role of the varicose and sinuous modes as they develop in a growing mean flow. In general, it is found that, for a given frequency parameter, the varicose mode has a shorter streamwise lifetime than the sinuous mode. For lower frequencies, the latter persists past the end of the potential core only to become subject to dissipation by the enhanced fine-scale turbulent activity in that region.

S0502-3-1 Manipulation two-dimensional turbulent jet using multiple rectangular notches : Turbulent flow properties

2010 ◽  
Vol 2010.2 (0) ◽  
pp. 167-168
Author(s):  
Shigetaka FUJITA ◽  
Takashi FARIMA ◽  
Nobuaki YOSHITAKE ◽  
Hideo OSAKA
Keyword(s):  
Turbulent Flow ◽  
Turbulent Jet ◽  
Two Dimensional ◽  
Flow Properties
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