scholarly journals The Effect of Sensor Dimensions on the Performance of Flexible Hot Film Shear Stress Sensors

Micromachines ◽  
2019 ◽  
Vol 10 (5) ◽  
pp. 305 ◽  
Author(s):  
Jin-Jin Wang ◽  
Hong Hu ◽  
Chao-Zhan Chen
Keyword(s):  
Shear Stress ◽  
Frequency Response ◽  
Flexible Substrate ◽  
Substrate Material ◽  
Film Sensor ◽  
Stress Sensors ◽  
Shear Stress Sensors ◽  
Length Width ◽  
Hot Film ◽  
Hot Film Sensor

This paper presents a study to determine the effect of sensor dimensions (length, width, and thickness) on the performance of flexible hot film shear stress sensors. The sensing component of a hot film sensor is nickel thermistor, and the flexible substrate material is polyimide. Several groups of flexible hot film shear stress sensors with different lengths, widths, and thicknesses were studied. The temperature coefficient of resistance (TCR) was measured. The TCR increased slightly with increasing thickness. The frequency response (time constant) of the flexible hot film shear stress sensor was obtained by the square wave, while the sensitivity was tested in a wind tunnel. The study found that as the sensor length was shortened, the frequency response increased, and the sensitivity decreased.

215 Development of micro-fabricated hot-film sensor by MEMS and study on its validation of the wall shear stress fluctuation measurement

2014 ◽  
Vol 2014.63 (0) ◽  
pp. _215-1_-_215-2_
Author(s):  
Takuya SAWADA ◽  
Osamu TERASHIMA ◽  
Yasuhiko SAKAI ◽  
Kouji Nagata ◽  
Mitsuhiro SHIKIDA ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Film Sensor ◽  
Stress Fluctuation ◽  
Wall Shear ◽  
Hot Film ◽  
Fluctuation Measurement ◽  
Hot Film Sensor

A Technique for the Measurement of Wall Shear Stress Based on Micro Fabricated Hot-Film Sensor

2013 ◽  
Author(s):  
Takuya Sawada ◽  
Osamu Terashima ◽  
Yasuhiko Sakai ◽  
Kouji Nagata ◽  
Mitsuhiro Shikida ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Turbulent Flows ◽  
Temporal Resolution ◽  
Large Scale ◽  
High Temporal Resolution ◽  
Film Sensor ◽  
Wall Shear ◽  
Hot Film ◽  
Hot Film Sensor

The objective of this study is to establish a technique for accurately measuring the wall shear stress in turbulent flows using a micro-fabricated hot-film sensor. Previously, we developed a hot-film sensor with a flexible polyimide-film substrate. This sensor can be attached to curved walls and be used in various situations. Furthermore, the sensor has a 20-μm-wide, heated thin metal film. However, the temporal resolution of this hot-film sensor is not very high owing to its substrate’s high heat capacity. Consequently, its performance is inadequate for measuring the wall shear stress “fluctuations” in turbulent flows. Therefore, we have developed another type of hot-film sensor in which the substrate is replaced with silicon, and a cavity has been introduced under the hot-film for reducing heat loss from the sensor and achieving high temporal resolution. Furthermore, for improving the sensor’s spatial resolution, the width of the hot-film is decreased to 10 μm. The structure of the hot-film’s pattern and the flow-detection mechanism are similar to those of the previous sensor. Experimental results show that new hot-film sensor works as expected and has better temporal resolution than the previous hot-film sensor. As future work, we will measure the wall shear stress for a turbulent wall-jet and discuss the relationship between a large-scale coherent vortex structure and wall shear stress based on data obtained using the new hot-film sensor.

scholarly journals On the measurement of wall shear stress with a patch-type micro-fabricated hot-film sensor

2014 ◽  
Vol 9 (3) ◽  
pp. JFST0029-JFST0029 ◽  
Author(s):  
Takuya SAWADA ◽  
Osamu TERASHIMA ◽  
Yasuhiko SAKAI ◽  
Kouji NAGATA ◽  
Mitsuhiro SHIKIDA ◽  
...  
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Film Sensor ◽  
Patch Type ◽  
Wall Shear ◽  
Hot Film ◽  
Hot Film Sensor

0203 Measurement of wall shear stress with a micro hot film sensor

2015 ◽  
Vol 2015 (0) ◽  
pp. _0203-1_-_0203-2_
Author(s):  
Sora MURAMATSU ◽  
Koji IWANO ◽  
Yasuhiko SAKAI ◽  
Yasumasa ITO ◽  
Mitsuhiro SHIKIDA
Keyword(s):  
Shear Stress ◽  
Wall Shear Stress ◽  
Film Sensor ◽  
Wall Shear ◽  
Hot Film ◽  
Hot Film Sensor

scholarly journals A Flexible Hot-Film Sensor Array for Underwater Shear Stress and Transition Measurement

Sensors ◽  
2018 ◽  
Vol 18 (10) ◽  
pp. 3469 ◽  
Author(s):  
Baoyun Sun ◽  
Pengbin Wang ◽  
Jian Luo ◽  
Jinjun Deng ◽  
Shiqi Guo ◽  
...  
Keyword(s):  
Shear Stress ◽  
Flat Plate ◽  
Sensor Array ◽  
Experimental Studies ◽  
Boundary Layer Transition ◽  
Empirical Formulas ◽  
Layer Transition ◽  
Film Sensor ◽  
Hot Film ◽  
Hot Film Sensor

A flexible hot-film sensor array for wall shear stress, flow separation, and transition measurement has been fabricated and implemented in experiments. Parylene C waterproof layer is vapor phase deposited to encapsulate the sensor. Experimental studies of shear stress and flow transition on a flat plate have been undertaken in a water tunnel with the sensor array. Compared with the shear stress derived from velocity profile and empirical formulas, the measuring errors of the hot-film sensors are less than 5%. In addition, boundary layer transition of the flat plate has also been detected successfully. Ensemble-averaged mean, normalized root mean square, and power spectra of the sensor output voltage indicate that the Reynolds number when transition begins at where the sensor array located is 1.82 × 105, 50% intermittency transition is 2.52 × 105, and transition finishes is 3.96 × 105. These results have a good agreement with the transition Reynolds numbers, as measured by the Laser Doppler Velocimetry (LDV) system.

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