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Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications

Lin, Qiao and Jiang, Fukang and Wang, Xuan-Qi and Xu, Yong and Han, Zhigang and Tai, Yu-Chong and Lew, James and Ho, Chih-Ming (2004) Experiments and simulations of MEMS thermal sensors for wall shear-stress measurements in aerodynamic control applications. Journal of Micromechanics and Microengineering, 14 (12). pp. 1640-1649. ISSN 0960-1317. http://resolver.caltech.edu/CaltechAUTHORS:LINjmm04

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Abstract

MEMS thermal shear-stress sensors exploit heat-transfer effects to measure the shear stress exerted by an air flow on its solid boundary, and have promising applications in aerodynamic control. Classical theory for conventional, macroscale thermal shear-stress sensors states that the rate of heat removed by the flow from the sensor is proportional to the 1/3-power of the shear stress. However, we have observed that this theory is inconsistent with experimental data from MEMS sensors. This paper seeks to develop an understanding of MEMS thermal shear-stress sensors through a study including both experimental and theoretical investigations. We first obtain experimental data that confirm the inadequacy of the classical theory by wind-tunnel testing of prototype MEMS shear-stress sensors with different dimensions and materials. A theoretical analysis is performed to identify that this inadequacy is due to the lack of a thin thermal boundary layer in the fluid flow at the sensor surface, and then a two-dimensional MEMS shear-stress sensor theory is presented. This theory incorporates important heat-transfer effects that are ignored by the classical theory, and consistently explains the experimental data obtained from prototype MEMS sensors. Moreover, the prototype MEMS sensors are studied with three-dimensional simulations, yielding results that quantitatively agree with experimental data. This work demonstrates that classical assumptions made for conventional thermal devices should be carefully examined for miniature MEMS devices.


Item Type:Article
Additional Information:© 2004 IOP Publishing Ltd. Received 19 March 2004, in final form 22 June 2004, Published 26 August 2004. The authors would like to thank Dr Steve Tung and Mr Chen-Wei Chiu for helpful discussions on MEMS shear-stress sensor fabrication and testing. This work was supported by AFOSR under Grant F49620-97-1-0514.
Record Number:CaltechAUTHORS:LINjmm04
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:LINjmm04
Alternative URL:http://stacks.iop.org/jm/14/1640
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:395
Collection:CaltechAUTHORS
Deposited By: Archive Administrator
Deposited On:09 Jun 2005
Last Modified:26 Dec 2012 08:40

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