Measurements and correlation of two-phase pressure drop under microgravity conditions

Experimental data of two-phase pressure drop obtained in normal gravity and in nearly zero-gravity aboard a NASA-JSC KC-135 aircraft has been used to test the accuracy of a number of empirically based correlations and flow-regime dependent models. For the reduced-gravity data, the algorithms tested were: Lockhart and Martinelli, Troniewski and Ulbrich, Friedel, Chisholm B., Beattie and Whalley, an annular flow model using the Premoli void fraction correlation, and an annular flow model with an interfacial friction factor which was developed from the KC-135 reduced-gravity data. For the ground test results, the two annular models were replaced by stratified flow models, i.e., the Taitel-Dukler and Chisholm models. Based oh this study, it was concluded that the pressure drops in reduced gravity and those of normal gravity are related to flow pattern models for each. The pressure drop predictions of the two annular flow models developed herein agreed well with the reduced-gravity data which were found to be significantly larger (by a factor of two or more) than the 1-G test data. The stratified models of Taitel-Dukler and Chisholm correlated best with the ground test data. For making predictions of two-phase pressure drop under microgravity conditions, flow-regime prediction and flow-regime dependent models appear essential.