题目：Compressible Dynamic Stall in an Unsteady Freestream
报告人：James W. Gregory Professor & Director（Aerospace Research Center, The Ohio State University）
时间：2017年11月3日上午9：00
地点：航空宇航学院A18-529报告厅
主办单位：直升机旋翼动力学国家级重点实验室、国际交流合作处、科协、航空宇航学院
报告摘要：
This presentation will discuss results from an experimental investigation of the compressible dynamic stall characteristics of an SSC-A09 airfoil in an unsteady freestream. While traditional dynamic stall investigations study only the pitch oscillation characteristics in a steady freestream, this work incorporates the effects of an unsteady freestream (time-varying velocity). The objective of this study is to evaluate the impact of local sinusoidal velocity that is encountered in the blade frame of reference on rotorcraft in forward flight. This investigation was undertaken in the Ohio State University 6′′ × 22′′ Unsteady Transonic Wind Tunnel. The pitch and/or flow can be oscillated at a rate up to 21 Hz (reduced frequency up to 0.05), with a Mach number of 0.40 ± 0.05 and a mean Reynolds number from 2 to 3.5 million. Steady data was also taken without freestream oscillations but with pitch oscillations, at Mach numbers ranging from 0.2 to 0.6. The effects of the phase relationship between the angle of attack and Mach oscillation waveforms were studied, in order to study the impact of the Mach oscillations on dynamic stall. Furthermore, the features of dynamic stall between a steady compressible and an unsteady compressible freestream were compared, in order to explore the feasibility of simulating unsteady freestream dynamic stall physics using data acquired with a steady freestream.
报告人简介：
Dr. James W. Gregory is a Professor in the Department of Mechanical and Aerospace Engineering, and Director of the Aerospace Research Center at The Ohio State University. He received his doctorate and master’s degrees in Aeronautics and Astronautics from Purdue University in 2005 and 2002, respectively. He received his Bachelor of Aerospace Engineering from Georgia Tech in 1999, graduating with highest honors. Dr. Gregory’s research interests lie in the field of unsteady aerodynamics � with specific interests in understanding and controlling compressible dynamic stall of rotorcraft blades; flow control of wakes, targeting three-dimensional wake structures and their instabilities; study of low-Re, unsteady rotor wakes subjected to wind gusts; and development of fast-response pressure-sensitive paint as a diagnostic for unsteady flows.He is also active in Unmanned Aircraft Systems (drone) research, including flight testing of vehicle performance, systems integration studies, and robust flight of UAS in all weather conditions (wind and icing).Funding for his work includes grants from ARO, ARL, AFOSR, AFRL, FAA, NASA, Sikorsky, Honda R&D, and the Ohio Federal Research Network.