A Temperature Sensor with Improved Performance and Reliability for Use at Low Mach Number and Density

The Aeropropulsion Systems Test Facility (ASTF) is a new USAF facility for testing large jet engines at controlled flight conditions. Successful control requires temperature measurements that are 1) highly accurate, 2) responsive, and 3) reliable. Duct wall temperatures that are considerably different from the airstream temperature lead to potentially large radiation and conduction errors. Low airflow velocity at some flight conditions presents problems in the area of response time. In addition, high reliability must be maintained when flight conditions produce a hostile environment of high wind loading and ice particles.

Sverdrup Technology, Inc., contract operator of ASTF, specified temperature sensors compatible with the control application and monitored a contract for their procurement. This paper presents the salient performance requirements, discusses the final design, and shows the test results. Care is taken throughout the paper to note design compromises that result from the strong coupling that exists among the performance parameters of accuracy, response, and reliability.