HEAT EXCHANGE AND CONDENSATION IN REDUCED GRAVITY

ABSTRACT The present investigation was sponsored by the NASA Reduced Gravity Student Flight Opportunity Program and was conducted by the University of Tennessee students aboard KC-135 in parabolic flights. The goal of the experiment was to study saturated air-water mixture to simulate the dynamics of condensation and heat exchange in two-phase flows and gain a better understanding of condensation under reduced gravity condition. In the experimental apparatus saturate air/water mixture is pumped through a one-inch cooled horizontal test pipe (condenser). Sets of thermocouples record change of temperature of liquid water, temperature of saturated air across the condenser, and temperature of liquid and fog after the test section. The water temperature measurements indicate lower water temperature and larger exit fog temperature at the condenser exit under reduced gravity as compared with normal gravity results. It was also observed that for relatively small water flow rate and velocity heat exchange between air and water streams was larger for reduced gravity conditions relative to normal gravity conditions

Research Engineer, AIAA Senior Member

A flight flutter experiment at the National Aeronautics and Space Administration (NASA) Dryden Flight Research Center, Edwards, California, used an 18-inch half-span composite model called the Aerostructures Test Wing (ATW). The ATW was mounted on a centerline flight test fixture on the NASA F-15B and used distributed piezoelectric strain actuators for in-flight structural excitation. The main focus of this paper is to investigate the performance of the piezoelectric actuators and test their ability to excite the first-bending and first-torsion modes of the ATW on the ground and in-flight. On the ground, wing response resulting from piezoelectric and impact excitation was recorded and compared. The comparison shows less than a 1-percent difference in modal frequency and a 3-percent increase in damping. A comparison of in-flight response resulting from piezoelectric excitation and atmospheric turbulence shows that the piezoelectric excitation consistently created an increased response in the wing throughout the flight envelope tested. The data also showed that to obtain a good correlation between the piezoelectric input and the wing accelerometer response, the input had to be nearly 3.5 times greater than the turbulence excitation on the wing