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A temperature probe using a small thermocouple wire with its axis placed normal to an airstream was designed, built and tested. The primary purpose of the probe is to measure the stagnation temperature distribution through a supersonic turbulent boundary layer. The small probe size permits measurements in the laminar sublayer region. The probe's simple geometric shape and design provides simplicity in determining the local gas temperature. Experiments were made to measure the local stagnation temperature of the flow with an accuracy of 5R over a moderate temperature range of 560R to 780R. (Author)
A temperature probe using a platinum 'hot-wire' which can be used to measure the local stagnation temperature in a hypersonic boundary layer was designed and tested. The temperature dependence of the wire properties is taken into account which greatly extends the probe's operating range. The primary function of the probe is to measure the temperature profiles in the sublayer. The small wire size (0.0001 inches) and suitable probe design make it possible to make measurements to within 0.003 inches of the wall. (Author).
The paper describes the results of a detailed experimental investigation of a two-dimensional turbulent boundary layer in a favorable pressure gradient where the free-stream Mach number varied from 3.8 to 4.6 and the ratio of wall to adiabatic-wall temperature has a nominal value of 0.82. Detailed profile measurements were made with pressure and temperature probes; skin friction was measured directly with a shear balance. The velocity- and temperature-profile results were compared with zero pressure gradient and incompressible results. The skin-friction data were correlated with momentum-thickness Reynolds number and pressure-gradient parameter. (Author).
A summary is presented of a research program aimed at the improvement of high-temperature strain gages of the electrical resistance type. Potential ceramic and metal components were evaluated and a gage was devised that was based on these evaluations. This gage (NBS 5B) was flexible and easy to install; however, it lacked resistance stability at higher temperatures. In an attempt to minimize this deficiency, ceramic cements were developed that showed greater electrical resistivity than had been previously observed in the range 800 to 1800 degrees Fahrenheit; also, a technique was devised for increasing the resistance to ground by applying a fired-on ceramic coating to the grid of a specifically developed unbacked gage. A study was made of the cause of the erratic response of cemented gages that had not been preheated prior to use. There were strong indications that the erratic response was caused mostly by the rapid decrease in resistance that accompanied structural changes in the cement.
A cold flow-field study of a rapid expansion, Mach 4.73, two-dimensional multiple nozzle array has been carried out in the hypersonic wind Tunnel. The nozzles are of the type used in a gas dynamic laser where the quality of the downstream flow field is important. The report examines the uniformity of the flow field in such a multiple nozzle array. Tests were conducted at supply conditions of 45 psia and 540 deg R. Pitot pressure, static pressure, and total temperature were measured along the axial, vertical, and horizontal centerlines within the nozzle and 21 nozzle exit heights downstream. Shadowgraph pictures provided qualitative flow field observations. The shock structure consisted of sidewall shocks, nozzle trailing edge shocks, and nozzle throat shocks. Viscous phenomena consisted of the boundary layers on the sidewalls and contoured walls, as well as the turbulent wakes caused by the trailing edges of the center nozzle blades. Mach number, static temperature, static density, and velocity profiles are presented. This flowfield information is useful to the prediction of the degradation of beam quality resulting from the non-homogeneity of a gas-dynamic-laser flowfield.