In most isentropic gas flows including the air, the difference between the recovery and the stagnation temperatures is proportional to the square root of the flow velocity. Based on this principle, RTA measures the recovery temperature distribution in a flow using a traversing thin thermocouple wire to estimate its flow velocity distribution. Although RTA resembles hot-wire anemometry at a glance, it has several advantages because of the concentrated sensitivity of a thermocouple wire on its contact point.
The paper uses a probe on which a thermocouple wire of 50μm diameter turns back at its contact point, which forms the probe vertex, to measure the recovery temperature distribution. Its results coincide with those using a thermocouple wire settled parallel to the flow, thus it is shown that the recovery factor of a thin wire is independent of the angle of incidence of flow. This fact allows RTA to employ a sensor of various shapes on a traverse of various structures, thus to be employed for various applications.