Simultaneous measurements of time-resolved velocity and concentration fields behind a sand dune-inspired jet in crossflow

2021 ◽  
Vol 33 (11) ◽  
pp. 115101
Author(s):  
Wenwu Zhou ◽  
Xu Zhang ◽  
Chuangxin He ◽  
Xin Wen ◽  
Jisheng Zhao ◽  
...  
Keyword(s):  
Sand Dune ◽  
Time Resolved ◽  
Jet In Crossflow ◽  
Simultaneous Measurements

scholarly journals Experimental and Numerical Investigation of Sweeping Jet Film Cooling

2017 ◽  
Vol 140 (3) ◽  
Author(s):  
Mohammad A. Hossain ◽  
Robin Prenter ◽  
Ryan K. Lundgreen ◽  
Ali Ameri ◽  
James W. Gregory ◽  
...  
Keyword(s):  
Film Cooling ◽  
Thermal Field ◽  
Numerical Study ◽  
Convective Heat Transfer Coefficient ◽  
Density Ratio ◽  
Vortex Pair ◽  
Lateral Direction ◽  
Time Resolved ◽  
Jet In Crossflow ◽  
Cooling Hole

A companion experimental and numerical study was conducted for the performance of a row of five sweeping jet (SJ) film cooling holes consisting of conventional curved fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of P/D = 8.5. Adiabatic film effectiveness (η), thermal field (θ), convective heat transfer coefficient (h), and discharge coefficient (CD) were measured at two different freestream turbulence levels (Tu = 0.4% and 10.1%) and four blowing ratios (M = 0.98, 1.97, 2.94, and 3.96) at a density ratio of 1.04 and hole Reynolds number of ReD = 2800. Adiabatic film effectiveness and thermal field data were also acquired for a baseline 777-shaped hole. The SJ film cooling hole showed significant improvement in cooling effectiveness in the lateral direction due to the sweeping action of the fluidic oscillator. An unsteady Reynolds-averaged Navier–Stokes (URANS) simulation was performed to evaluate the flow field at the exit of the hole. Time-resolved flow fields revealed two alternating streamwise vortices at all blowing ratios. The sense of rotation of these alternating vortices is opposite to the traditional counter-rotating vortex pair (CRVP) found in a “jet in crossflow” and serves to spread the film coolant laterally.

Experimental and Numerical Investigation of Sweeping Jet Film Cooling

2017 ◽  
Author(s):  
Mohammad A. Hossain ◽  
Robin Prenter ◽  
Ryan K. Lundgreen ◽  
Ali Ameri ◽  
James W. Gregory ◽  
...  
Keyword(s):  
Film Cooling ◽  
Thermal Field ◽  
Numerical Study ◽  
Convective Heat Transfer Coefficient ◽  
Density Ratio ◽  
Vortex Pair ◽  
Lateral Direction ◽  
Time Resolved ◽  
Jet In Crossflow ◽  
Cooling Hole

A companion experimental and numerical study was conducted of the performance of a row of 5 sweeping jet (SJ) film cooling holes consisting of conventional curved fluidic oscillators with an aspect ratio (AR) of unity and a hole spacing of P/D = 8.5. Adiabatic film effectiveness (η), thermal field (θ), convective heat transfer coefficient (h) and discharge coefficient (CD) were measured at two different freestream turbulence levels (Tu = 0.4% and 10.1%) and four blowing ratios (M = 0.98, 1.97, 2.94 and 3.96) at a density ratio (DR) of 1.04 and hole Reynolds number of ReD = 2800. Adiabatic film effectiveness and thermal field data were also acquired for a baseline 777-shaped hole. The sweeping jet film cooling hole showed significant improvement in cooling effectiveness in the lateral direction due to the sweeping action of the fluidic oscillator. An unsteady RANS simulation was performed to evaluate the flow field at the exit of the hole. Time resolved flow fields revealed two alternating streamwise vortices at all blowing ratios. The sense of rotation of these alternating vortices is opposite to the traditional counter rotating vortex pair (CRVP) found in a ‘jet in crossflow’ and serves to spread the film coolant laterally.

Picosecond Dynamics of Laser Annealing

1981 ◽  
Vol 4 ◽  
Author(s):  
Dae M. Kim ◽  
Rajiv R. Shah ◽  
D. Von Der Linde ◽  
D.L. Crosthwait
Keyword(s):  
Electron Microscopy ◽  
Laser Annealing ◽  
Point Of View ◽  
Plasma Model ◽  
Reflection And Transmission ◽  
Time Resolved ◽  
Low Intensity ◽  
Simultaneous Measurements ◽  
Thermal Melting ◽  
Scanning Electron

ABSTRACTWe report simultaneous measurements of time resolved reflection and transmission of low intensity 1.06 μm, 35 ps pulses subsequent to excitation of 50 KeV, 1016 cm−2 boron implanted silicon by 0.53 μm 35 ps pulses of varying energy densities. The samples are examined by optical and scanning electron microscopy in conjunction with defect etching. These data are discussed from the point of view of both the thermal melting model and plasma model.

scholarly journals Time-resolved x-ray emission from laser-produced plasmas with timing fiducial

1986 ◽  
Vol 4 (3-4) ◽  
pp. 495-498 ◽  
Author(s):  
W. Lampart ◽  
J. E. Balmer
Keyword(s):  
High Temperature ◽  
Laser Pulse ◽  
Laser Pulses ◽  
Incident Laser ◽  
Trailing Edge ◽  
Time Resolved ◽  
X Ray ◽  
Simultaneous Measurements ◽  
Incident Laser Pulse ◽  
Driving Pulse

High-temperature plasmas were produced by focusing 1·05 μm, 100 psec laser pulses onto Al layer targets at a mean irradiation of 3·1013 Watt/cm2. By means of simultaneous measurements of the thermal x-ray emission and the frequency-quadrupled laser pulse we observe a 20 ± 15 psec delay of the x-ray peak relative to the peak of the incident laser pulse. In addition, modulations on the trailing edge of the driving pulse appear strongly enhanced in the x-ray signature.

Time Resolved PIV Measurements of a Slot Lobed Jet Issuing Into a Crossflow

2021 ◽  
Author(s):  
Michael Lewandowski ◽  
Paul Kristo ◽  
Abdullah Weiss ◽  
Mark Kimber
Keyword(s):  
Velocity Ratio ◽  
Leading Edge ◽  
Residual Effects ◽  
Low Velocity ◽  
Mean Velocity ◽  
Time Resolved ◽  
Freestream Velocity ◽  
Round Jet ◽  
Jet In Crossflow ◽  
Turbulent Statistics

Abstract The near field mixing phenomenon created by a round jet with three slot lobes exhausting into a crossflow are investigated at a velocity ratio of 0.5. Time-resolved particle image velocimetry measurements provide instantaneous velocity fields of the slotted jet in crossflow, allowing for evaluation of the first and second order turbulent statistics in two perpendicular planes of interest. The independently controlled jet exit and crossflow inlet are first characterized extensively to confirm the velocity ratio and anticipated momentum exchanges. Spanwise and transverse mean velocity profiles reveal that the interaction of the three slot lobes and the center round jet primarily occur in the immediate jet exit region, though residual effects are also found in the wake. Evaluation of the Reynold stresses aims to quantify the near region mixing between the jets collated geometric features and their interaction with the crossflow. Frequency analysis reveals that low-frequency harmonics in the wake region provide greater energy contributions than that of the higher-frequency harmonics found along the leading edge shear layer. This behavior is attributed to the low velocity ratio, where the freestream velocity is twice as large as the jet exit velocity. The experimental data and observations herein serve analogous computational modeling efforts for the slotted jet in crossflow at low velocity ratios, with ample information to inform necessary boundary conditions, fluid properties, and flow fields for validation.

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