Supersonic,High Reynolds Number Flow Over a Tangent Ogive Cylinder at Small Angles of Attack. An Experimental Study and Comparison with Theory.

摘要

An experimental investigation was made of flow over a tangent ogive cylinder model at small angle of attack. The model was approximately 10 calibers (50cm, 20in.) long with a 3 caliber nose. Surface pressure distributions have been measured in both the circumferential and axial directions and boundary layer pitot surveys made at four stations along with wind and lee sides of the cylinder. Over the entire angle of attack range tested, 0 through 5 deg, no boundary layer separation was observed. All the measurements were made at a nominal freestream Mach number of 3, a unit Reynolds number of 6.2 x 10 to the 7th power/m (1.6 million/in.) and with near adiabatic wall conditions. At these high Reynolds numbers, natural boundary layer transition occurred, and in all cases was observed close to the nose tip. The measurements were compared with predictions from a boundary layer based computer code developed by Sturek, et al, at the U.S. Army Ballistic Research Laboratories. Pressure distributions agree well with the predictions. The experimental and computed velocity profiles have some common trends but there exist significant discrepancies between them. In a general sense, the computed and measured profiles have fundamentally different shapes and their downstream development is not accurately modelled, particularly on the windside.