scholarly journals Pitched and Yawed Circular Jets in Cross-Flow

2002 ◽  
Author(s):  
Ivana M. Milanovic ◽  
K. B. M. Q. Zaman
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Turbulence Intensity ◽  
Momentum Flux ◽  
Cross Flow ◽  
Flux Ratio ◽  
Streamwise Velocity ◽  
Streamwise Vorticity ◽  
Downstream Distance ◽  
Circular Jets

Results from an experimental investigation of flow field generated by pitched and yawed jets discharging from a flat plate into a cross-flow are presented. The circular jet was pitched at α = 20° and 45° and yawed between β = 0° and 90° in increments of 15°. The measurements were performed with two X-wires providing all three components of velocity and turbulence intensity. These data were obtained at downstream locations of x = 3, 5, 10 and 20, where the distance x, normalized by the jet diameter, is measured from the center of the orifice. Data for all configurations were acquired at a momentum-flux ratio J = 8. Additionally, for selected angles and locations, surveys were conducted for J = 1.5, 4, and 20. As expected, the jet penetration is found to be higher at larger α. With increasing β the jet spreads more. The rate of reduction of peak streamwise vorticity, ωxmax, with the downstream distance is significantly lessened at higher β but is found to be practically independent of α. Thus, at the farthest measurement station x = 20, ωxmax is about five times larger for β = 75° compared to the levels at β = 0°. Streamwise velocity within the jet-vortex structure is found to depend on the parameter J. At J = 1.5 and 4, ‘wake-like’ velocity profiles are observed. In comparison, a ‘jet-like’ overshoot is present at higher J.

Experimental Investigation of Liquid Jet Breakup in a Cross Flow of a Swirling Air Stream

2014 ◽  
Vol 136 (6) ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari ◽  
Saadat Syed ◽  
Jeffery A. Lovett
Keyword(s):  
Experimental Investigation ◽  
Momentum Flux ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Penetration Behavior

This paper presents the results of an experimental investigation of liquid jet breakup in a cross flow of air under the influence of swirl (swirl numbers 0 and 0.2) at a fixed air flow Mach number 0.12 (typical gas turbine conditions). The experiments have been conducted for various liquid to air momentum flux ratios (q) in the range of 1 to 25. High speed (@ 500 fps) images of the jet breakup process are captured and those images are processed using matlab to obtain the variation of breakup length and penetration height with momentum flux ratio. Using the high speed images, an attempt has been made to understand the physics of the jet breakup process by identification of breakup modes—bag breakup, column breakup, shear breakup, and surface breakup. The results show unique breakup and penetration behavior which departs from the continuous correlations typically used. Furthermore, the images show a substantial spatial fluctuation of the emerging jet resulting in a wavy nature related to effects of instability waves. The results with 15 deg swirl show reduced breakup length and penetration related to the nonuniform distribution of velocity that offers enhanced fuel atomization in swirling fuel nozzles.

Investigation of Flow Characteristics in a Combustor With Opposed Jets

2018 ◽  
Author(s):  
Yongbin Ji ◽  
Bing Ge ◽  
Shusheng Zang
Keyword(s):  
Flow Field ◽  
Gas Turbine ◽  
Momentum Flux ◽  
Flow Characteristics ◽  
Cross Flow ◽  
Flux Ratio ◽  
Main Flow ◽  
3D Flow ◽  
Momentum Flux Ratio ◽  
High Efficient

Jet-in-cross flow (JICF) has been investigated broadly because of its wide engineering application, for example in the gas turbine field, film cooling on the turbine vanes and blades, primary and dilution jets in the combustors and so on. In the gas turbine combustors, the main flow is generated by the swirlers to stabilize the flame, which induces complicated 3D flow characteristics. Different from uniform main flow, swirling cross flow has a strong tangential velocity component, which will deflect the jets in the circumferential direction as well as in the streamwise direction. So, the degradation behavior of the jets is more complex than that in the uniform cross flow. This paper presents PIV measurement of the flow field inside of a three-nozzle annular combustor with opposed quenching jets on the liner walls. Dry ice as a newly proposed flow tracer was proposed and tried. The momentum flux ratio and jet holes configuration are studied to evaluate their effects on the primary recirculation zone, downstream flow field. Finally, numerical simulation was also performed to reveal 3D flow characteristics as well as turbulent kinetic energy generation. The results show that momentum flux ratio has a dominant influence on flow characteristics in the combustor. Getting better understanding of jets behavior in the swirling cross flow helps optimization design of quenching or dilution holes geometry and arrangement for the gas turbine combustor, which turns to be very beneficial to the low-emission and high efficient combustor development.

Experimental Investigation of Liquid Jet Breakup in Cross Flow of Swirling Air Stream

2013 ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari ◽  
Saadat Syed ◽  
Jeffery A. Lovett
Keyword(s):  
Experimental Investigation ◽  
Momentum Flux ◽  
High Speed ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Breakup Process ◽  
Breakup Length ◽  
Jet Breakup ◽  
Penetration Behavior

This paper presents the results of an experimental investigation of liquid jet breakup in a cross-flow of air under the influence of swirl (swirl numbers 0 and 0.2) at a fixed air flow Mach No. 0.12 (typical gas turbine conditions). The experiments have been conducted for various liquid to air momentum flux ratios (q) in the range of 1 to 25. High speed (@ 500 fps) images of the jet breakup process are captured and those images are processed using MATLAB to obtain the variation of breakup length and penetration height with momentum flux ratio. Using the high speed images, an attempt has been made to understand the physics of the jet breakup process by identification of breakup modes — bag breakup, column breakup, shear breakup and surface breakup. The results show unique breakup and penetration behavior which departs from the continuous correlations typically used. Furthermore, the images show a substantial spatial fluctuation of the emerging jet resulting in a wavy nature related to effects of instability waves. The results with 15° swirl show reduced breakup length and penetration related to the non-uniform distribution of velocity that offers enhanced fuel atomization in swirling fuel nozzles.

Structure of a streamwise-oriented vortex incident upon a wing

2017 ◽  
Vol 816 ◽  
pp. 306-330 ◽  
Author(s):  
C. McKenna ◽  
M. Bross ◽  
D. Rockwell
Keyword(s):  
Root Mean Square ◽  
Cross Flow ◽  
Leading Edge ◽  
Streamwise Velocity ◽  
Mean Square ◽  
Swirl Ratio ◽  
Streamwise Vorticity ◽  
Image Velocimetry ◽  
Unsteady Loading ◽  
Drag Ratio

Impingement of a streamwise-oriented vortex upon a fin, tail, blade or wing represents a fundamental class of flow–structure interaction that extends across a range of applications. It can give rise to unsteady loading known as buffeting and to changes of the lift to drag ratio. These consequences are sensitive to parameters of the incident vortex as well as the location of vortex impingement on the downstream aerodynamic surface, generically designated as a wing. Particle image velocimetry is employed to determine patterns of velocity and vorticity on successive cross-flow planes along the vortex, which lead to volume representations and thereby characterization of the streamwise evolution of the vortex structure as it approaches the downstream wing. This evolution of the incident vortex is affected by the upstream influence of the downstream wing, and is highly dependent on the spanwise location of vortex impingement. Even at spanwise locations of impingement well outboard of the wing tip, a substantial influence on the structure of the incident vortex at locations significantly upstream of the leading edge of the wing was observed. For spanwise locations close to or intersecting the vortex core, the effects of upstream influence of the wing on the vortex are to: decrease the swirl ratio; increase the streamwise velocity deficit; decrease the streamwise vorticity; increase the azimuthal vorticity; increase the upwash; decrease the downwash; and increase the root-mean-square fluctuations of both streamwise velocity and vorticity. The interrelationship between these effects is addressed, including the rapid attenuation of axial vorticity in presence of an enhanced defect of axial velocity in the central region of the vortex. When the incident vortex is aligned with, or inboard of, the tip of the wing, the swirl ratio decreases to values associated with instability of the vortex, thereby giving rise to enhanced values of azimuthal vorticity relative to the streamwise (axial) vorticity, as well as relatively large root-mean-square values of streamwise velocity and vorticity.

scholarly journals Drop Size Characteristics of Forward Angled Injectors in Subsonic Cross Flows

2013 ◽  
Author(s):  
Venkat S. Iyengar ◽  
Sathiyamoorthy Kumarasamy ◽  
Srinivas Jangam ◽  
Manjunath Pulumathi
Keyword(s):  
Gas Turbine ◽  
Test Section ◽  
Momentum Flux ◽  
Drop Size ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Axial Distance ◽  
Momentum Flux Ratio ◽  
Spray Plume

Cross flow fuel injection is a widely used approach for injecting liquid fuel in gas turbine combustors and afterburners due to the higher penetration and rapid mixing of fuel and the cross flowing airstream. Because of the very limited residence time available in these combustors it is essential to ensure that smaller drop sizes are generated within a short axial distance from the injector in order to promote effective mixing. This requirement calls for detailed investigations into spray characteristics of different injector configurations in a cross-flow environment for identifying promising configurations. The drop size characteristics of a liquid jet issuing from a forward angled injector into a cross-flow of air were investigated experimentally at conditions relevant to gas turbine afterburners. A rig was designed and fabricated to investigate the injection of liquid jet in subsonic cross-flow with a rectangular test section of cross section measuring 50 mm by 70 mm. Experiments were done with a 10 degree forward angled 0.8 mm diameter plain orifice nozzle which was flush mounted on the bottom plate of test section. Laser diffraction using Malvern Spraytec particle analyzer was used to measure drops size and distributions in the near field of the spray. Measurements were performed at a distance of 70 mm from the injector at various locations along the height of the spray plume for a reasonable range of liquid flow rates as in practical devices. The sprays were characterized using the non dimensional parameters such as the Weber number and the momentum flux ratio and drop sizes were measured at three locations along the height of the spray from the bottom wall. The momentum flux ratio was varied from 5 to 25. Results indicate that with increase in momentum flux ratio the SMD reduced at the specific locations and an higher overall SMD was observed as one goes from the bottom to the top of the spray plume. This was accompanied by a narrowing of the drop size distribution.

Effect of Cross-Flow Swirl on the Trajectory of Spray in an Annular Passage

2020 ◽  
Author(s):  
Tushar Sikroria ◽  
Abhijit Kushari
Keyword(s):  
Momentum Flux ◽  
High Speed ◽  
Air Flow ◽  
Cross Flow ◽  
Flux Ratio ◽  
Liquid Jet ◽  
Swirl Number ◽  
Flow Swirl ◽  
Air Stream ◽  
The Impact

Abstract This paper presents the experimental analysis of the impact of swirl number of cross-flowing air stream on liquid jet spray trajectory at a fixed air flow velocity of 42 m/s with the corresponding Mach number of 0.12. The experiments were conducted for 4 different swirl numbers (0, 0.2, 0.42 and 0.73) using swirl vanes at air inlet having angles of 0°, 15°, 30° and 45° respectively. Liquid to air momentum flux ratio (q) was varied from 5 to 25. High speed (@ 500 fps) images of the spray were captured and those images were processed using MATLAB to obtain the path of the spray at various momentum flux ratios. The results show interesting trends for the spray trajectory and the jet spread in swirling air flow. High swirling flows not only lead to spray with lower radial penetration due to sharp bending and disintegration of liquid jet, but also result in spray with high jet spread and spray area. Based on the results, correlations for the spray path have been proposed which incorporates the effects of the swirl number of the air flow.

Momentum Exchanges and Energy Transfers in Cross Flow Fans

1987 ◽  
Author(s):  
Joseph Mazur ◽  
Trilochan Singh
Keyword(s):  
Experimental Investigation ◽  
Flow Field ◽  
Cross Flow ◽  
Operating Conditions ◽  
Energy Transfers ◽  
Cross Flow Fan

An experimental investigation of the flow in a cross flow fan at three operating conditions is reported. Velocity and pressure maps for the flow field are presented along with a determination of the momentum exchanges and energy transfers between the blading and the flow field regions.

Experimental Investigation on Flow Field Characteristics by Drag Reducing Agent Additives in Stirred Vessel

2019 ◽  
Author(s):  
Xueyu Qi ◽  
Ting Wu ◽  
Yiming Chen ◽  
Ke Yang ◽  
Wei Zhao ◽  
...  
Keyword(s):  
Experimental Investigation ◽  
Energy Dissipation ◽  
Flow Field ◽  
Turbulence Intensity ◽  
Dissipation Rate ◽  
Energy Dissipation Rate ◽  
High Concentration ◽  
Stirred Vessel ◽  
Inhibition Effect ◽  
Flow Field Characteristics

Abstract In this paper, experimental investigation on two oil-soluble DRAs were carried out in stirred vessel by standard six-blade Rushton, based on the application of particle image velocimeter (PIV). Two DRAs (1# and 2#) with different concentration from 3 ppm to 50 ppm were added into diesel respectively, and speed of impeller speed was set 400 rpm. Flow field characteristics including turbulence intensity, turbulent kinetic energy, energy dissipation rate influenced by those additives in stirred vessel were study. It was found that inhibition effect of turbulence intensity of the two DRAs is not obvious with concentration below 10 ppm. However, when concentration is above 10 ppm, turbulence inhibition effect become more obvious. Under low concentration, 1# has better turbulence inhibition effect in area near impeller, while 2# has better turbulence inhibition effect under high concentration. When the two DRAs are under the same concentration of 50ppm, turbulent flow energy and energy dissipation rate are obviously reduced.

Velocity and Turbulence Intensity Profiles Downstream of a Long Reach Endwall Double Row of Film Cooling Holes in a Gas Turbine Combustor Representative Environment

2015 ◽  
Author(s):  
Irene Cresci ◽  
Peter T. Ireland ◽  
Marko Bacic ◽  
Ian Tibbott ◽  
Anton Rawlinson
Keyword(s):  
Flow Field ◽  
Turbulence Intensity ◽  
Film Cooling ◽  
Momentum Flux ◽  
Diameter Ratio ◽  
Double Row ◽  
Length Scales ◽  
Cylindrical Holes ◽  
Endwall Film Cooling ◽  
Film Cooling Holes

The continuous demand from the airlines for reduced jet engine fuel consumption results in increasingly challenging high pressure turbine nozzle guide vane (NGV) working conditions. The capability to reproduce realistic boundary conditions in a rig at the combustor-turbine interaction plane is a key feature when testing NGVs in an engine-representative environment. A large scale linear cascade rig to investigate NGV leading edge cooling systems has been designed with particular attention being paid to creating engine representative conditions at the inlet to the NGVs. The combustor simulator replicates the main features of a rich-burn design including large dilution jets and extensive endwall film cooling. A three-dimensional computational domain including the entire combustor simulator has been created and RANS CFD simulations have been run in order to match Reynolds number and mainstream-to-coolant momentum flux ratio; velocity and turbulence measurements have been acquired at the NGV inlet plane at ambient temperature. In this engine-representative environment the authors focused their attention on the flow field downstream of different endwall film cooling holes configurations: three arrangements of a double row of staggered cylindrical holes (lateral pitch-to-diameter ratio of 2–3–6) and one with intersecting holes (intersecting angle of 90°) are experimentally and numerically analyzed. Velocity, turbulence intensity and integral length scales are predicted and measured for a density ratio of 1 and coolant-to-mainstream momentum flux of 6. A hot wire sensor was mounted on a two-axis traverse mechanism able to move the probe in the spanwise and lateral directions. Three slots allowed to reposition the traverse and take measurements at three downstream locations (stream-wise distance-to-diameter ratio of 4.2–9.2–14.2). The research confirmed the strong influence of the endwall coolant on the flow field at the NGV inlet plane and the hole spacing results a key parameter in managing the film development. Closer-spaced hole configurations can assure an effective film coverage. The integral length scales are strongly connected to the hole diameter and spacing. Intersecting holes can potentially reduce the amount of required coolant at a fixed pressure ratio, but they offer worst film performance than cylindrical holes. RANS simulations proved to be able to get the main trends shown by the measurements.

scholarly journals Structure and mixing of a transverse jet in incompressible flow

1984 ◽  
Vol 148 ◽  
pp. 405-412 ◽  
Author(s):  
J. E. Broadwell ◽  
R. E. Breidenthal
Keyword(s):  
Flow Field ◽  
Incompressible Flow ◽  
Momentum Flux ◽  
Free Stream ◽  
Normal Force ◽  
Cross Flow ◽  
Vortex Pair ◽  
Water Jet ◽  
Transverse Jet ◽  
Axial Vortex

The flow field induced by a jet in incompressible cross-flow is analysed and the results compared with those obtained in a reacting water-jet experiment. It is argued that the axial vortex pair in the flow arises from the jet momentum normal to the free stream, the momentum flux being equivalent to a normal force, i.e. to a lift.

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