Stagnation Temperature Probes for Use at High Supersonic Speeds and Elevated Temperatures

Abstract

Stagnation temperature probes with single platinum or gold coated shields made of silica (or other material of low thermal conductivity) were built for use at high supersonic speeds and elevated temperatures. For free-stream Reynolds numbers of the order of 40,000 the temperature recovery factor of the probes reaches .996. It decreases with decreasing Reynolds number and increasing temperature. At temperatures up to 8000 K the major thermometric losses of the probes are conduction losses. A single calibration curve is obtained for each probe by relating the calibration data to the flow conditions inside the probe. This calibration curve facilitates the evaluation of flow data from measured pressure and temperature data alone without resorting to any assumptions. Small probes of 1 mm height at tho air entrance wore successfully used for temperature surveys of turbulent boundary layers on the nozzle wall of the. hyporsonic tunnel.

Temperature measurement in the flowing medium

“…Referential probe characteristics (variant 1) is in the whole range more or less constant and near 1, which means that from the viewpoint of the total temperature measurement quality this is the best designed probe tested within this study. Similar results can be found in the original literature [5].…”

“…Variant 0 is a common insulated sealed thermocouple or another cylindrical sensor passing through the flown-by wall and reaching with its active part the flowing medium, see the two following figures. The following three figures show the geometry of total parameters probes, variant 1 being the reference probe whose geometry was taken from [5]. Variant 2 and variant 3 are designed solutions where besides the resistance sealed sensor Pt1000 also total pressure take-off is fitted.…”

Experimental Study of Strut Injectors for Scramjet Combustors: Total Pressure Losses in a Selected<br /> Supersonic Streamwise Vortex Interaction Mode

“…6. 15 In this work this Reynolds number is approximately 1.2 × 10 5 , well above the aforementioned limit. The recovery factor of the probes was calculated by means of the outcomes of a combined shadowgraph/temperature measurement test.…”

“…Variation of the recovery factor against the freestream Reynolds number based on the probe's diameter 15. …”

Handbook of supersonic aerodynamics. Section 20. Wind tunnel instrumentation and operation

“…168, the conduction error is much greater 0 than the radiation error. This is reflected in the fact that increasing the length of exposed thermocouple wires reduces the total error by increasing the area over which convective heat transfer takes place.…”