Quandt 



forces are severe enough so that the phases will be rather uniformly mixed and 

 performance independent of gravitational orientation. 



Professor Pallabazzer, on the other hand, assumes that the flow pattern 

 will be more or less homogeneous, but questions the best approach to describ- 

 ing the internal transport properties of turbulent air-water mixtures. With re- 

 gard to the heat transfer and particle drag coefficient values used in the paper, 

 I wish to say that I believe them to be consistent and conservative for the pur- 

 poses of this analysis. In my opinion only experimental data will be able to re- 

 solve the proper magnitude. Concerning the initial conditions for the particle - 

 gas flow analysis, it is possible to create a spectrum of initial velocity and 

 pressure conditions by varying water spray nozzle and air duct areas. It is also 

 possible to control the homogeneity of the initial mixture by variations in design 

 of the injection station. Although it may seem desirable to design for an initially 

 homogeneous air-water mixture, cases may be conceived where some controlled 

 maldistribution of air and water would actually improve thrust augmentation. 

 Finally, I appreciate the information concerning the earlier work by Kliegel on a 

 particle -gas flow analysis. 



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