LIQUID-VAPOR FLOW REGIME TRANSISTIONS FOR USE IN DESIGN OF HEAT TRANSFER LOOPS IN SPACECRAFT

LOW SPEED, TWO PHASE (VAPOR-LIQUID) FLOW REGIMES ARE IMPORTANT TO SEVERAL SIGNIFICANT HEAT TRANSFER PROBLEMS IN SPACECRAFT. LOW SPEED FLOW RATES ALSO CREATE THE MOST GRAVITY-AFFECTED FLOW REGIMES. HIGH SPEED FLOW RATES CREATE FLOW REGIMES THAT ARE AFFECTED LITTLE BY GRAVITY. FEW STUDIES EXIST WHICH GIVE AN OVERVIEW OF FLOW REGIMES IN ZERO GRAVITY. IN PARTICULAR, FEW STUDIES HAVE ATTEMPTED TO USE RECENT SUCCESSFUL AND LARGELY ANALYTICAL FLOW REGIME MODELS (WHICH INCLUDE GRAVITY) AS A STARTING POINT FOR FLOW REGIME MODELING IN ZERO GRAVITY. AETA PROPOSES TO CONDUCT TWO PHASE FLOW REGIME LAB TESTS ON EARTH WHICH ELIMINATES EFFECT OF GRAVITY BY USING FLOW OF WATER AND OIL OF EQUAL DENSITY. IN ADDITION, WE WILL: USE TWO RECENT, NEARLY ANALYTICAL FLOW REGIME PREDICTION MODELS TO INDICATE PROBABLE FLOW REGIMES IN VERY REDUCED (AND ALSO ZERO) GRAVITY. ONE OF THESE MODELS HAS ALREADY BEEN COMPUTERIZED BY AETA AND USED TO OBTAIN PRELIMINARY LOW GRAVITY RESULTS. TO CREATE A FIRST-ORDER ANALYTICAL MODEL TO PREDICT FLOW REGIMES IN ZERO GRAVITY, USING LAB AND SEMI-ANALYTICAL COMPUTER STUDIES. TO SUGGEST AREAS FOR VERY FOCUSED TWO PHASE FLOW EXPERIMENTAL WORK IN TRUE GRAVITY CONDITIONS; TO SUGGEST AREAS FOR MORE FOCUSED ANALYTICAL EFFORT.