Modern Physics Letters B Vol. 30, No. 15 (2016) 1650177 (16 pages) c  World Scientific Publishing Company DOI: 10.1142/S0217984916501773 MEMS flexible thermal flow sensor for measurement of boundary layer separation Jui-Ming Yu, Tzong-Shyng Leu ∗ and Jiun-Jih Miau Department of Aeronautics and Astronautics, National Cheng Kung University, Tainan 70101, Taiwan ∗ tsleu@mail.ncku.edu.tw Shih-Jiun Chen Department of Mechanical Engineering, Temple University, Philadelphia, PA 19122, USA Received 18 October 2015 Revised 5 January 2016 Accepted 11 February 2016 Published 27 May 2016 Micro-electro-mechanical systems (MEMS) thermal flow sensors featured with high spa- tial resolutions, fast frequency response and minimal interference with fluid flow have been applied widely in boundary-layer studies and aerodynamic flow sensing and con- trol due to the inherent outstanding performances. In this study, MEMS thermal flow sensors were designed and fabricated on a flexible skin using the MEMS technology. The dimension of a single sensing element was 200 μm × 260 μm, which had a resistance of about 200 Ω after annealing. By configuring thermal flow sensors in either a single thermal flow sensor and a thermal tuft sensor, separation points of a two-dimensional (2D) LS(1) 0417 airfoil at various angles of attack could be precisely detected. The ex- perimental results show good agreement with the hot wire sensor and particle traced flow visualization in detecting the separation point on the suction surface of the airfoil. Keywords : Flexible MEMS thermal flow sensor; flow separation. 1. Introduction The measurement of separation in the boundary layer is significant in many flow testing and flow control application. 1,2 Several techniques of experimental measure- ments and theoretical model relative to separation point and reattachment of airfoil could be found in the literature. For instance, flow visualization can offer qualita- tive data in excellent, and hot-wire anemometry has been frequently employed to measure the quantitative data of the flow field. Micro-electro-mechanical systems ∗ Corresponding author. 1650177-1 Mod. Phys. Lett. B 2016.30. Downloaded from www.worldscientific.com by WSPC on 06/12/16. For personal use only.