Centerline Velocity Decay of Compressible Free Jets

AbstractThis paper presents a computational analysis of effects of swirling co-flow and non-circular subsonic compressible inner jets on centerline velocity decay, mass entrainment and jet spreading rate. Three different exit shapes of elliptical, rectangular and circular inner jets were compared for three different co-flow conditions such as no co-flow, straight co-flow and swirling co-flow. Co-flow is issuing from a circular annular duct. Swirling co-flow is created in the co-flow duct by introducing a swirler with stationary angular vanes of 50° oblique to the jet axis. Reynolds number of inner jet is calculated based on its equivalent diameter as 200342. It is found that the swirling co-flow has strong influence on the boundary condition of inner jet and alters the major features of the jet such as jet potential core length, centerline velocity decay rate and jet spread rate. Streamwise corner vortices of different jet conditions have been captured using velocity vector plot to show the effect of swirling co-flow on the jet flow field. Swirling co-flow with elliptical inner jet exhibits higher velocity decay rate and jet spreading rate than the equivalent area circular and rectangular jet.

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Center-Line Velocity Decay in Coaxial Free Jets

Journal of Applied Mechanics ◽

10.1115/1.3423621 ◽

1975 ◽

Vol 42 (2) ◽

pp. 514-516 ◽

Cited By ~ 3

Author(s):

C. S. Lenzo ◽

T. N. Dalai

Keyword(s):

Center Line ◽

Free Jets ◽

Velocity Decay

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Mean Streamwise Centerline Velocity Decay and Entrainment in Triangular and Circular Jets

AIAA Journal ◽

10.2514/1.j051559 ◽

2013 ◽

Vol 51 (1) ◽

pp. 70-79 ◽

Cited By ~ 11

Author(s):

W. R. Quinn ◽

M. Azad ◽

D. Groulx

Keyword(s):

Centerline Velocity ◽

Circular Jets ◽

Velocity Decay

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The jet centerline velocity decay method for noninvasive calculation of aortic regurgitant volume

Journal of the American College of Cardiology ◽

10.1016/s0735-1097(96)82511-3 ◽

1996 ◽

Vol 27 (2) ◽

pp. 395 ◽

Cited By ~ 1

Author(s):

Russell S. Heinrich ◽

Michael Jones ◽

Izumi Yamada ◽

Jennifer McGhee ◽

Takahiro Shiota ◽

...

Keyword(s):

Centerline Velocity ◽

Regurgitant Volume ◽

Velocity Decay

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Momentum Flux Development From Three-Dimensional Free Jets

Journal of Fluids Engineering ◽

10.1115/1.3448277 ◽

1976 ◽

Vol 98 (2) ◽

pp. 256-260 ◽

Cited By ~ 2

Author(s):

J. P. Narain

Keyword(s):

Axial Velocity ◽

Momentum Flux ◽

Three Dimensional ◽

Core Region ◽

Potential Region ◽

Potential Core ◽

Free Jets ◽

Flow Development ◽

Velocity Decay

The momentum-flux development from three-dimensional free jets has been investigated. The analysis is presented for free jets from circular, triangular, rectangular and elliptical orifices. The bluff jets, with eccentricity near unity, show the usual potential region and the axisymmetric decay region for the maximum axial velocity decay. The slender jets, with smaller than one eccentricity values, show three zones of flow development. The potential core region is followed by a characteristic decay region where velocity decay is dependent on the shape and eccentricity of the orifice. The maximum axial velocity of all slender jets finally decay axisymmetrically with increasing downstream distances.

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Dynamic characteristics of supersonic turbulent free jets from four types of circular nozzles

International Journal of Nonlinear Sciences and Numerical Simulation ◽

10.1515/ijnsns-2020-0071 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Mingli He ◽

Guang Zhang ◽

Shaohua Hu ◽

Cheng Wang

Keyword(s):

Dynamic Characteristics ◽

Axial Velocity ◽

Working Pressure ◽

Perfect Agreement ◽

Potential Core ◽

Free Jets ◽

Eddy Simulation ◽

Work Pressure ◽

Velocity Decay ◽

Spreading Rates

Abstract The effects of nozzle structures and working pressure on the dynamic characteristics of supersonic turbulent free jets have been investigated numerically. Four types of nozzles (namely Laval, pipe, contraction I, and contraction II, respectively) and four pressure conditions (namely K = 0.8, 1, 1.5, and 2, respectively) were considered. A Standard k-ε model was utilized for the calculation of the supersonic turbulent free jets. Validation of the model was performed on the Laval jet by comparing it with the experiment and large-eddy simulation (LES). A perfect agreement was achieved in terms of the centerline and radial axial velocity profiles. The jets issuing from the Laval and the pipe had a longer potential core and a larger centerline axial velocity with the same outlet momentum. The length of the potential core was proportional to the working pressure, but variations of the centerline axial velocity decay rate were inverse for all nozzles. The effects of nozzle structures and work pressure on the spreading rates of the jets were insignificant. No obvious change trend could be observed on the kinematic and geometric virtual origins. The study can provide references for the nozzle and working pressure selection in practical application.

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Three-Dimensional Free Jets

Journal of the Royal Aeronautical Society ◽

10.1017/s0001924000053847 ◽

1967 ◽

Vol 71 (684) ◽

pp. 858-859

Author(s):

N. Rajaratnam ◽

K. Subramanya

Keyword(s):

Three Dimensional ◽

Flow Characteristics ◽

Maximum Velocity ◽

Potential Core ◽

Free Jets ◽

Axisymmetric Jet ◽

Plane Jets ◽

Velocity Decay ◽

Different Shapes ◽

Semi Empirical

Fairly elegant semi-empirical theories are available for predicting the turbulent diffusion of axisymmetric and plane jets. However, there are relatively few investigations on the non-axisymmetric jets, herein denoted as three-dimensional jets. The extensive investigations conducted at the Polytechnic Institute of Brooklyn on three-dimensional jets have shown that the flow field is characterised by three distinct regions; the potential core, the characteristic decay (CD) region and the axisymmetric decay (AD) region. In the CD region the velocity profiles in the direction of the minor axis are similar but the maximum velocity decay curves are different for different shapes. In the AD region the flow characteristics are similar to that of an axisymmetric jet. Yevdjevich has recently conducted another investigation on rectangular jets.

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