KC-135 Flight Testing of Void Fraction Capacitance Probe for Microgravity Two-Phase Flow

摘要

This report describes the work performed under a NASA Johnson Space Center grant to perform flight testing of a void fraction capacitance probe in the microgravity environment aboard the KC-135. The overall goal of this project is to validate and calibrate the capacitance sensor in a microgravity environment. This project has been conducted with the cooperation of Goddard Space Flight Center (test bed), Lewis Research Center and Creare Inc. (capacitance void fraction sensors and instrumentation), Johnson Space Center, Texas A&M Center for Space Power, and the Interphase Transport Phenomena Laboratory (data acquisition and integration of equipment for KC-135 flights). Twelve KC-135 flights were conducted in three series. Test points were collected over a wide range of void fractions (O - 90 ). Data were collected from stratified, slug, and annular flow regimes. Void fraction measurements from the capacitance sensors were compared with the void fractions from a trapped volume in the test section between two quick closing valves. Under the annular flow regime, void fractions measured by the capacitance sensors compared well with values from the trapped volume. In slug flow regime, some discrepancies between the sensors and trapped volumes were found. However, when the working fluid (Suva) mass flow rate increased from 0.416 lb./min. to 1.00 lb./min., the void fraction measurements between the capacitance sensors and the trapped volume had better agreement. Overall, the FRIM experimental package produced satisfactory test conditions in the microgravity conditions of the KC-135 aircraft, to validate and calibrate the Creare capacitance void fraction sensors.