Flow measurements downstream of a single bleed hole in a subsonic, turbulent boundary layer using a new 5-hole pressure probe

Abstract

[This paper presents measurements of the flow features downstream of a single bleed hole in a subsonicl turbulent boundary layer, using a new parallel tube 5-hole pressure probe and other investigative techniques. The design and technique of use of the parallel tube probe (herein referred to as a “pitchpipe” probe for brevity) is discussed. A comparison of the new probe with a standard probe in a flow field normally suitable for standard 5-hole probes was conduct+ to verify that the new probe could resolve the flow pld with comparable accuracy. The geometry of the pnchpipe probe allowed measurements in the large velocity gradients of the boundary layer downs&m of the bleed holes. Bleed and flow measurements were made in the NASA Lewis Research Center (LeRC) 15 x 15cm Supersonic Wind Tunnel, at a mean freestream Mach number of 0.60. Results are presented for two bleed hole geometries, one peaendicular to the free stream and one at an angle of120° to the l&e stream. Mass flow surveys showed the angled hole to be a more efficient hole for mass flow removal. Pitot surveys in transverse planes downstream of the holes revealed a region of a more full boundary layer. Pitchpipe probe surveys in this area located two regions of contra-rotating vorticity, which was seen to decrease in strength in the downstream direction. *Aerospace Engineer, Space Concepts Analysis Section , Member AIAA +Professor, Dept. of Mechanical and Aerospace Engineering, Associate Fellow AIAA. *Aerospace Engineer, Inlet, Duct, and Nozzle Flow Physics Branch, Member AIAA. Comrkht Q 1999 by the American Institute of Aeronautics ,__ and Astronqtics, Inc. No copy-right is asserted in the United States under Title 17, U.S. Code. The U.S. Government has a royalty-free license to e&x&w all rights under the copyright claimed herein for Government& purposes. All other rights are reserved by the copy-right owner. I A B