Investigation of Supersonic Jet Interaction With Hypersonic Cross Flow

2015 ◽  
Vol 137 (10) ◽  
Author(s):  
S. L. N. Desikan ◽  
R. Saravanan ◽  
S. Subramanian ◽  
A. E. Sivararamakrishnan ◽  
S. Pandian
Keyword(s):  
Pressure Ratio ◽  
Supersonic Jet ◽  
Cross Flow ◽  
Injection Port ◽  
Strong Function ◽  
Jet Interaction ◽  
Oil Flow ◽  
Flow Features ◽  
Horseshoe Vortices ◽  
Oil Flow Visualization

This paper presents the interaction of a highly underexpanded supersonic jet of Mjet = 3.19 with hypersonic cross flow (M∞ = 6). The jet interaction flowfield was studied through wall static pressure measurement, Schlieren, and oil flow visualization. The results clearly demonstrate that flow separation is a strong function of jet pressure ratio (PR). To understand the overall flow physics, numerical simulations were also carried out. The flow features such as primary, secondary, tertiary, and quaternary vortex in separated boundary layer, horseshoe vortices, and its foot print downstream of the injection port were predicted well.

Visualization and measurement of supersonic jet flow field evolution issuing from a rectangular nozzle with aft-deck

2020 ◽  
Vol 34 (14n16) ◽  
pp. 2040092
Author(s):  
Yun Jiao ◽  
Chengpeng Wang ◽  
Wenshuo Wang ◽  
Keming Cheng
Keyword(s):  
Shear Stress ◽  
Flow Visualization ◽  
Near Field ◽  
Pressure Ratio ◽  
Supersonic Jet ◽  
Surface Flow ◽  
Rectangular Nozzle ◽  
Great Consistency ◽  
Oil Flow ◽  
Oil Flow Visualization

An experimental study is reported of supersonic jet surface flow structure visualization and wall shear stress field measurement issuing from a rectangular nozzle with aft-deck. The near-field surface flow structures evolution from over-expansion to under-expansion with the increase of nozzle pressure ratio (NPR) are successfully captured by surface oil flow visualization and shear sensitive liquid crystal coating (SSLCC) technique. The quantitative measurement result of shear stress vector field obtained by SSLCC shows that shear stress directions change significantly across the shock wave and expansion fans, while the magnitudes of shear stress have no obvious changes. Surface streamlines calculated by SSLCC image keep great consistency with the streamlines visualized using oil flow technique, which demonstrates the accuracy and potential application of SSLCC in supersonic jet surface flow visualization.

Experimental Study of Stream-Wise Vortex Formation on Swept Circular Cylinders in Cross-Flow

2015 ◽  
Author(s):  
W. D. E. Allan ◽  
J. P. Gostelow ◽  
Simon I. Hogg
Keyword(s):  
Vortex Formation ◽  
Cross Flow ◽  
Vortex Pair ◽  
Experimental Results ◽  
Circular Cylinders ◽  
Data Sets ◽  
Oil Flow ◽  
Turbomachinery Blades ◽  
Oil Flow Visualization ◽  
Series Of Experiments

A series of experiments has been undertaken on a swept cylinder in cross-flow in the 2m2 open-jet wind-tunnel at Durham University, at a nominal Reynolds Number of 500,000. Boundary layer instability, leading to transition has been attributed to curious sheets of stream-wise vortices on turbomachinery blades and other airfoils. Cylinders in cross-flow can be scaled to model such flows. Empirical analysis of stream-wise vortex pair spacing on cylinders was proposed in 1970 and various researchers have produced experimental data sets at various Reynolds Numbers and sweep ranges. Oil flow visualization was conducted in this work, the goal of which was to fill an important gap in experimental results, a gap of significance to turbine blade designers amongst others. In this test campaign, clear evidence of stream-wise vortices was exposed, the wavelengths of which compared well with the experimental results of others and with theory, although interesting departures were observed at high sweep angles. A physical explanation for the formation of the vortex and pair spacing, particularly at higher sweeps, is proposed.

Measurement and Computation of Flowfield in Transonic Turbine Nozzle Blading With Blunt Trailing Edges

2009 ◽  
Author(s):  
J. P. Gostelow ◽  
A. Mahallati ◽  
S. A. Andrews ◽  
W. E. Carscallen
Keyword(s):  
Mach Number ◽  
Large Scale ◽  
Pressure Ratio ◽  
Time Resolved ◽  
High Pressure Ratio ◽  
Blunt Trailing Edge ◽  
Pressure Distributions ◽  
Oil Flow ◽  
Oil Flow Visualization ◽  
Total Temperature

Experimental and computational results are presented from cascade testing on the nozzle blading of a high pressure ratio single stage turbine. Testing on this blading in 1986 showed surprising evidence of a redistribution of the downstream total temperature field. The nozzle midspan section has subsequently been tested in a large scale low aspect ratio planar cascade, having a continuous room-temperature inlet flow, to obtain more detailed information over the subsonic and transonic speed ranges. The blades had a blunt trailing edge which caused strong von Ka´rma´n vortex shedding throughout the subsonic range. This was shown to result in Eckert-Weise effect temperature redistribution. The first time-resolved measurements of this effect were measured in this cascade. Unusual vortex configurations were also observed at transonic speeds. The purpose of the current observations was to obtain reliable time-averaged measurements of flow through the cascade, which is proving to be an excellent vehicle for validating CFD predictions. A three-hole finger probe was traversed at the inlet and outlet of the cascade to evaluate the aerodynamic performance. Mach number and base pressure distributions, together with schlieren and surface oil-flow visualization, aided understanding of flow and loss behavior. Two-dimensional numerical simulations were performed over the speed range. The results assisted understanding of the influence of Mach number on losses and flow structures, specifically the shock configurations and base pressures. Comparisons of numerical results and experimental measurements of the flow-field showed good agreement.

scholarly journals MECHANISMS OF GENERATION AND SOURCES OF NOISE IN SUPERSONIC JETS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 144-150
Author(s):  
Vladislav Emelyanov ◽  
Aleksey Tsvetkov ◽  
Konstantin Volkov
Keyword(s):  
Pressure Ratio ◽  
Supersonic Jet ◽  
Numerical Data ◽  
Jet Flows ◽  
Noise Generation ◽  
Noise Sources ◽  
Cavity Depth ◽  
Flow Parameters ◽  
Nozzle Pressure ◽  
Physical Pattern

Interest in the development of models and methods focused on the mechanisms of noise generation in jet flows is due to strict noise requirements produced by various industrial devices, as well as the possibilities of using sound in engineering and technological processes. The tools of physical and computational modeling of gas dynamics and aero-acoustics problems are considered, and noise sources and mechanisms of noise generation in supersonic jet flows are discussed. The physical pattern of the flow in free supersonic under-expanded jets is discussed on the basis of experimental and numerical data, as well as the flow structure arising from the interaction of a supersonic under-expanded jet with a cylindrical cavity. The influence of the nozzle pressure ratio and cavity depth on the sound pressure level, amplitude and frequency characteristics of the flow parameters is studied.

Effects of Core Flow Swirl on the Flow Characteristics of a Scalloped Forced Mixer

2011 ◽  
Author(s):  
Zhijun Lei ◽  
Ali Mahallati ◽  
Mark Cunningham ◽  
Patrick Germain
Keyword(s):  
Pressure Ratio ◽  
Velocity Ratio ◽  
Flow Characteristics ◽  
Pressure Probe ◽  
Streamwise Vortices ◽  
Core Flow ◽  
The Core ◽  
Flow Swirl ◽  
Swirl Angle ◽  
Oil Flow

This paper presents a detailed experimental investigation of the influence of core flow swirl on the mixing and performance of a scaled turbofan mixer with 12 scalloped lobes. Measurements were made downstream of the mixer in a co-annular wind tunnel. The core-to-bypass velocity ratio was set to 2:1, temperature ratio to 1.0, and pressure ratio to 1.03, giving a Reynolds number of 5.2 × 105, based on the core flow velocity and equivalent hydraulic diameter. In the core flow, the background turbulence intensity was raised to 5% and the swirl angle was varied using five vane geometries from 0° to 30°. Seven-hole pressure probe measurements and surface oil flow visualization were used to describe the flowfield and the mixer performance. At low swirl angles, additional streamwise vortices were generated by the deformation of normal vortices due to the scalloped lobes. With increased core swirl, greater than 10°, the additional streamwise vortices were generated mainly due to radial velocity deflection, rather than stretching and deformation of normal vortices. At high swirl angles, stronger streamwise vortices and rapid interaction between various vortices promoted downstream mixing. Mixing was enhanced with minimal or no total pressure and thrust losses for the inlet swirl angles less than 10°. However, the reversed flow downstream of the center-body was a dominant contributor to the loss of thrust at the maximum core flow swirl angle of 30°.

Effects of Freestream Turbulence on the Losses of a Highly-Loaded Compressor Stator Blade

2003 ◽  
Author(s):  
J. W. Douglas ◽  
S.-M. Li ◽  
B. Song ◽  
W. F. Ng ◽  
Toyotaka Sonoda ◽  
...  
Keyword(s):  
Turbulence Intensity ◽  
Flow Separation ◽  
Reynolds Numbers ◽  
Freestream Turbulence ◽  
Suction Surface ◽  
Flow Losses ◽  
Oil Flow ◽  
Oil Flow Visualization ◽  
Inlet Conditions ◽  
High Reynolds

Very little published literature documents the effects of different freestream turbulence intensities on compressor flows at realistically high Reynolds numbers. This paper presents a study of these effects on a transonic, linear, compressor stator cascade. The cascade consisted of high turning stator airfoils that had the camber of 55 degrees. The effects of freestream turbulence intensities of approximately 0.1% (baseline) and 1.6% were examined. Inlet Mach numbers to the cascade were tested from 0.55 to 0.89. Reynolds numbers, based on the inlet conditions and blade chord, varied between 1.0–2.0×106. Inlet flow angles to the cascade ranged from a choking to a stall condition. For the baseline cases, at most positive incidence angles to the cascade, surface oil flow visualization and Schlieren pictures showed a significant flow separation on the suction surface of the blade. Under these conditions, the increase in freestream turbulence from 0.1% to 1.6% significantly reduced the flow losses of the cascade (by as much as 57% in some cases). In other test conditions where no evidence depicted flow separation on the blade, there were no measurable effects on the losses due to the increase in freestream turbulence intensity. In addition, the increase of freestream turbulence intensity also improved the effective operating range of the cascade significantly (e.g., by 46% or higher).

Experimental investigation of plasma vortex generator in flow control

2018 ◽  
Vol 92 (3) ◽  
pp. 376-385
Author(s):  
Alireza Ghayour ◽  
Mahmoud Mani
Keyword(s):  
Vortex Generator ◽  
Leading Edge ◽  
Streamwise Vortex ◽  
Flow Visualisation ◽  
Content Type ◽  
Oil Flow ◽  
Order Of Magnitude ◽  
Oil Flow Visualization ◽  
Unsteady Operation ◽  
Naca 0012

Purpose The purpose of this paper is to compare the effects of two different configurations of plasma streamwise vortex generators (PSVG), including comb-type and mesh-type in controlling flow. This is demonstrated on the NACA 0012 airfoil. Design/methodology/approach The investigations have been done experimentally at the various electric and aerodynamic conditions. The surface oil flow visualization method has been used to the better understanding of the flow physics and the interaction of the oncoming flow passing over the airfoil and the vortex generated by comb-type PSVG. Findings This paper demonstrates the potential capabilities of the mesh-type and comb-type PSVGs in controlling flow in unsteady operation. It was found that the vortex generated by the mesh-type PSVG in unsteady operation was an order of magnitude stronger than comb-type PSVG. The flow visualisation technic proved that only a part of the plasma actuator is effective in the condition that the actuator is installed only on a portion of the upper surface of the airfoil. Originality/value This paper experimentally confirms the capabilities of the mesh-type PSVG unsteady operation in compare with comb-type PSVG in controlling flow, whereby recommends using mesh-type PSVG in the leading edge in front of comb-type PSVG on the entire wingspan to prevent the stall.

Jet interaction at supersonic cross flow conditions

Shock Waves ◽  
2003 ◽  
Vol 13 (1) ◽  
pp. 13-23 ◽  
Author(s):  
F. Seiler ◽  
P. Gnemmi ◽  
H. Ende ◽  
M. Schwenzer ◽  
R. Meuer
Keyword(s):  
Cross Flow ◽  
Flow Conditions ◽  
Jet Interaction
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