Impact pressure and total temperature interpretation at hypersonic mach numbers

An experimental investigation was undertaken at a nominal Mach number of 5.6 in the GALCIT Hypersonic Wind Tunnel, Leg No. 1. The first phase was an investigation of the viscous effects on measured impact pressures. The second was an investigation of the temperature recovery characteristics of a singly shielded total-temperature probe. Experimental results are presented for a straight, sharp-lipped, cylindrical, impact-pressure probe and for a flattened-end probe. Impact-pressure data were obtained for a Reynolds number range from 425 to 8,000, where the Reynolds number was based on free stream conditions and the impact probe outside diameter, The data show that the Rayleigh equation requires corrections for viscous effects at Reynolds numbers less than 6,000 for the circular sharp-tipped probe and less than 4,000 for the flattened-end probe. The viscous effects increase with decreasing Remolds numbers. At a Reynolds number of 425, the measured impact pressure is approximately 2.5 per cent lower than that predicted by the Rayleigh equation. It was concluded that the viscous effects were dependent on Mach number as well as Reynolds number. Temperature recovery factors for the total-temperature probe were obtained throughout a Reynolds number range from 30,800 to 213,000, where the Reynolds number was based on the probe entrance outside diameter and the free stream conditions. An analysis of suitable parameters with which to present the data is included together with the experimental data. For a limited range of total temperatures, a single temperature recovery calibration curve was obtained when the Reynolds number was used as a parameter. The data show that the temperature recovery factor of the total temperature probe decreases with decreasing Reynolds numbers