Air-Water Jet (Mist-Jet) for Ship Propulsion 



compression. The rate of temperature decay is given by combining the gas 

 energy equation with the particle heat-transfer equation 



dx D Cp pn Vfl W -■-■ • ■' '^ - '^ '. 



For many cases of interest, the initial decrease in gas temperature is so rapid 

 that the gas quickly approaches the liquid temperature. Expansion will there- 

 fore occur at almost constant temperature as the liquid resupplies energy to the 

 gas during the drop in pressure along the nozzle. Hence, it will be assumed, 

 conservatively, that the nozzle expansion is isothermal at the liquid tempera- 

 ture. This results in a certain loss in available compressor work, and may be 

 thought of as an inherent loss in gas-liquid systems where the energy is added 

 primarily to the gas phase. Figure 4 shows the fraction of isentropic work that 

 may be recovered from a gas which expands isothermally at ambient tempera- 

 ture for a range of pressure ratios. This approximation to the energy efficiency 

 may be written in general as 





In V 



Ul V) 

 I UJ 



30 4.0 



PRESSURE RATIO. 



Fig. 4 - Fraction of isentropic work that 

 maybe recovered from a gas which expands 

 isothermally at ambient temperature for a 

 range of pressure ratios 



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