The Interaction of a Sonic Jet with a Surrounding Subsonic Stream

SummaryAn investigation has been made into the effects of a surrounding stream on an “under-expanded” sonic jet. Experiments were performed for different Mach numbers of the surrounding stream and for different ratios of the static pressure in the jet at the exit to that in the external stream. It was found that the base-flow region produced at the exit of the nozzle, due to the finite thickness of the nozzle walls, had a significant effect on the flow field. Schlieren photographs suggest that the surrounding stream has little effect on the first cell of the jet but that the second cell is, in general, lengthened when a surrounding stream is present. In most cases it is longer than the first cell. Conditions at the beginning of the second cell are probably different from those at the beginning of the first cell and it is suggested that the lengthening of the second cell is mainly a secondary effect due to the alteration in the velocity distribution of the first cell caused by the external stream. A theoretical investigation was made, using an inviscid model of the flow. The flows in the jet and the stream were calculated independently and the jet boundary determined using an iterative procedure. For the free jet, a study was made of the various approximations to the sonic exit conditions and into the errors involved in the numerical solution of the supersonic region. A comparison of the calculated length of the first cell of the jet with the experimental results showed reasonable agreement for the free jet. For a jet with a surrounding stream the inviscid model predicted that the length would be significantly increased as the Mach number of the stream was increased from zero; this effect was not found in the experiments. A modification to the model is suggested and it has been found that, using this, the results are in better agreement with the experiments.

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Influence of bypass ratio on subsonic and correctly expanded sonic co-flowing jets with finite lip thickness

Proceedings of the Institution of Mechanical Engineers Part G Journal of Aerospace Engineering ◽

10.1177/0954410018782511 ◽

2018 ◽

Vol 233 (7) ◽

pp. 2536-2548 ◽

Cited By ~ 4

Author(s):

S Thanigaiarasu ◽

R Naren Shankar ◽

E Rathakrishnan

Keyword(s):

Total Pressure ◽

Strong Influence ◽

Static Pressure ◽

Pressure Variation ◽

Jet Mixing ◽

Free Jet ◽

Pressure Decay ◽

Sonic Jet ◽

Mach Numbers ◽

Bypass Ratio

The effects of bypass ratio on co-flowing subsonic and correctly expanded sonic jet decay have been studied experimentally. Co-flowing jets with lip thickness 1.0 Dp (where Dp is the diameter of primary nozzle and is equal to 10 mm) with bypass ratios of around 0.7, 1.4, and 6.4 at primary jet exit Mach numbers 0.6, 0.8, and 1.0 have been analyzed. A single free jet equivalent to primary nozzle of the co-flowing nozzle was considered for comparison. Primary jet centerline total pressure decay, spread, and static pressure variation were investigated. The results show that the mixing of the high bypass ratio co-flowing jet with lip thickness 1.0 Dp is superior to low bypass ratio co-flowing jet. Both lip thickness and bypass ratio have a strong influence on the co-flowing jet mixing. Bypass ratio 6.3 experiences a significantly higher mixing than bypass ratio 0.7 and 1.4. Selected jets were also investigated computationally. The computations capture the salient flow physics and reproduce well with the experiments.

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Base Flow Characteristics of a Linear Aerospike Nozzle Segment

Journal of Engineering for Industry ◽

10.1115/1.3438135 ◽

1973 ◽

Vol 95 (1) ◽

pp. 353-359 ◽

Cited By ~ 1

Author(s):

T. J. Mueller ◽

W. P. Sule

Keyword(s):

Static Pressure ◽

Pressure Ratio ◽

Flow Characteristics ◽

Flow Region ◽

Base Flow ◽

Base Pressure ◽

Wake Flow ◽

Pressure Distributions ◽

Base Bleed ◽

Aerospike Nozzle

The separated base flow region within a linear aerospike nozzle segment is investigated experimentally in an ejector-diffuser system. The nozzle-diffuser system and base pressure characteristics are described over the pressure ratio range from the “open wake” to the “closed wake” operation. Schlieren photographs and static pressure distributions along the test section centerline and top contour describe the transition, from “open wake” to “closed wake” flow fields. Base pressure and static pressure distributions are utilized to present the effects of a ramp diffuser. The effects of base bleed on the base pressure ratio and structure of the nozzle flow field are also presented.

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Static pressure distribution in the free turbulent jet

Journal of Fluid Mechanics ◽

10.1017/s0022112057000440 ◽

1957 ◽

Vol 3 (1) ◽

pp. 1-16 ◽

Cited By ~ 98

Author(s):

David R. Miller ◽

Edward W. Comings

Keyword(s):

Static Pressure ◽

Longitudinal Velocity ◽

Fluid Motion ◽

Mean Velocity ◽

Free Jet ◽

Static Pressure Distribution ◽

Two Dimensional Flow ◽

The Common ◽

Jet Theory ◽

Made In

Measurements of mean velocity, turbulent stress and static pressure were made in the mixing region of a jet of air issuing from a slot nozzle into still air. The velocity was low and the two-dimensional flow was effectively incompressible. The results are examined in terms of the unsimplified equations of fluid motion, and comparisons are drawn with the common assumptions and simplifications of free jet theory. Appreciable deviations from isobaric conditions exist and the deviations are closely related to the local turbulent stresses. Negative static pressures were encountered everywhere in the mixing field except in the potential wedge region immediately adjacent to the nozzle. Lateral profiles of mean longitudinal velocity conformed closely to an error curve at all stations further than 7 slot widths from the nozzle mouth. An asymptotic approach to complete self-preservation of the flow was observed.

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Investigation of Large-Scale Structures in Supersonic Planar non-reactive Shear Layer with a Base Flow Region

51st AIAA/SAE/ASEE Joint Propulsion Conference ◽

10.2514/6.2015-4141 ◽

2015 ◽

Author(s):

Jiping Wu ◽

Hailong Zhang ◽

Jian Chen ◽

Yuxin Zhao

Keyword(s):

Shear Layer ◽

Large Scale ◽

Flow Region ◽

Base Flow ◽

Large Scale Structures ◽

Scale Structures

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Pressure-Probe Interference in a Vortex Flow

Transactions of the Canadian Society for Mechanical Engineering ◽

10.1139/tcsme-1978-0016 ◽

1978 ◽

Vol 5 (2) ◽

pp. 106-110

Author(s):

O.O. Mojola

Keyword(s):

Vortex Flow ◽

Static Pressure ◽

Vertical Wall ◽

Three Dimensional ◽

Flow Region ◽

Pressure Probe ◽

Pressure Data ◽

Pressure Sensing ◽

Recirculation Flow ◽

Made In

This paper examines the sensitivity of vortex-flows to disturbances arising from the insertion of conventional pressure-sensing probes into the flows. With a wide variety of pitot-tubes, static-pressure probes, and transverse-cylinder yawmeters, measurements were made in the vortex (recirculation) flow region of a separated, three-dimensional, turbulent boundary layer upstream of a vertical wall. The measurements, which included both local and surface pressure data, have been analysed to reveal how the shape, size, and alignment of probes independently and collectively contribute to the probe interference.

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Experimental and computational study of square cylinder wakes with two-dimensional injection into the base flow region

European Journal of Mechanics - B/Fluids ◽

10.1016/j.euromechflu.2003.09.004 ◽

2004 ◽

Vol 23 (2) ◽

pp. 353-365 ◽

Cited By ~ 17

Author(s):

Panayiotis Koutmos ◽

Demosthenes Papailiou ◽

Andreas Bakrozis

Keyword(s):

Computational Study ◽

Flow Region ◽

Base Flow ◽

Two Dimensional ◽

Square Cylinder ◽

Cylinder Wakes

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Transient Axial Free Jet Impinging Over a Flat Uniformly Heated Disk: Solid–Fluid Properties Effects

10.1115/imece2000-1543 ◽

2000 ◽

Author(s):

Antonio J. Bula ◽

Muhammad M. Rahman ◽

John E. Leland

Keyword(s):

Heat Transfer ◽

Steady State ◽

Transfer Process ◽

Conjugate Heat Transfer ◽

Finite Thickness ◽

Heat Transfer Process ◽

Transport Processes ◽

Liquid Region ◽

Free Jet ◽

Wide Range

Abstract Transient conjugate heat transfer process during axial free jet impingement on a solid disk of finite thickness was considered. As the fluid reached steady state, power was turned on and a uniform heat flux was imposed on the disk at its opposite surface. The numerical model considered both solid and fluid regions. Equations for conservation of mass, momentum, and energy were solved in the liquid region taking into account the transport processes at the inlet and exit boundaries, as well as at the solid-liquid and liquid-gas interfaces. Inside the solid, only the heat conduction equation was solved. The shape and location of the free surface (liquid-gas interface) was determined iteratively as a part of the solution process by satisfying the kinematic condition as well as the balance of normal and shear forces at this interface. A non-uniform grid distribution, captured from a systematic grid-independence study, was used to adequately accommodate large variations near the solid-fluid interface. Computed results include the simulation of six different substrate materials namely, aluminum, constantan, copper, diamond, silicon, and silver, and three different impinging liquids, FC - 77, Mil - 7808, and water. The solids and fluids selected covered a wide range of possibilities of conjugate heat transfer phenomena. The analysis performed showed that the thermal storage capacity, defined as density times specific heat, is an important factor defining which material will attain steady state faster during conjugate heat transfer process, like the thermal diffusivity does it for pure conduction heat transfer.

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