A compliant wall sensor array for detecting pressure fluctuation signatures in separating boundary layers

1997 ◽  
Author(s):  
D. Pal ◽  
S. Sinha ◽  
D. Banerjee ◽  
C. Baker ◽  
M. Pandey ◽  
...  
Keyword(s):  
Boundary Layers ◽  
Pressure Fluctuation ◽  
Sensor Array ◽  
Compliant Wall

scholarly journals Effect of compliant wall motion on turbulent boundary layers

1977 ◽  
Vol 20 (10) ◽  
pp. S31 ◽  
Author(s):  
Dennis M. Bushnell ◽  
Jerry N. Hefner ◽  
Robert L. Ash
Keyword(s):  
Boundary Layers ◽  
Wall Motion ◽  
Turbulent Boundary Layers ◽  
Compliant Wall

Effect of wall cooling on boundary-layer-induced pressure fluctuations at Mach 6

2017 ◽  
Vol 822 ◽  
pp. 5-30 ◽  
Author(s):  
Chao Zhang ◽  
Lian Duan ◽  
Meelan M. Choudhari
Keyword(s):  
Boundary Layer ◽  
Boundary Layers ◽  
Wall Temperature ◽  
Pressure Fluctuation ◽  
Free Stream ◽  
Pressure Fluctuations ◽  
Turbulent Boundary Layers ◽  
Wall Pressure ◽  
Wall Region ◽  
Near Wall

Direct numerical simulations of turbulent boundary layers with a nominal free-stream Mach number of $6$ and a Reynolds number of $Re_{\unicode[STIX]{x1D70F}}\approx 450$ are conducted at a wall-to-recovery temperature ratio of $T_{w}/T_{r}=0.25$ and compared with a previous database for $T_{w}/T_{r}=0.76$ in order to investigate pressure fluctuations and their dependence on wall temperature. The wall-temperature dependence of widely used velocity and temperature scaling laws for high-speed turbulent boundary layers is consistent with previous studies. The near-wall pressure-fluctuation intensities are dramatically modified by wall-temperature conditions. At different wall temperatures, the variation of pressure-fluctuation intensities as a function of wall-normal distance is dramatically modified in the near-wall region but remains almost intact away from the wall. Wall cooling also has a strong effect on the frequency spectrum of wall-pressure fluctuations, resulting in a higher dominant frequency and a sharper spectrum peak with a faster roll-off at both the high- and low-frequency ends. The effect of wall cooling on the free-stream noise spectrum can be largely accounted for by the associated changes in boundary-layer velocity and length scales. The pressure structures within the boundary layer and in the free stream evolve less rapidly as the wall temperature decreases, resulting in an increase in the decorrelation length of coherent pressure structures for the colder-wall case. The pressure structures propagate with similar speeds for both wall temperatures. Due to wall cooling, the generated pressure disturbances undergo less refraction before they are radiated to the free stream, resulting in a slightly steeper radiation wave front in the free stream. Acoustic sources are largely concentrated in the near-wall region; wall cooling most significantly influences the nonlinear (slow) component of the acoustic source term by enhancing dilatational fluctuations in the viscous sublayer while damping vortical fluctuations in the buffer and log layers.

TMR Magnetic Sensor Array Module for Detecting Leakage Current in Lithium-ion Batteries

2017 ◽  
Vol 137 (8) ◽  
pp. 481-486
Author(s):  
Junichi Hayasaka ◽  
Kiwamu Shirakawa ◽  
Nobukiyo Kobayashi ◽  
Kenichi Arai ◽  
Nobuaki Otake ◽  
...  
Keyword(s):  
Lithium Ion Batteries ◽  
Leakage Current ◽  
Sensor Array ◽  
Lithium Ion ◽  
Magnetic Sensor
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