Design Of Closed Circulating Gas Turbine With Metal Fuel

Unmanned Underwater Vehicle?UUV?with the closed cycle using metal fuel?MFCC?are important arms favored by navies.As the crucial components of UUV,the propulsion system has been deeply investigated When metals are selected as fuel,UUV's the weigh and position of gravity center do not change.Besides,the combustion efficiency of UUV will never be reduced by backpressure and there will be no emissions left.That means enemies won't find any obvious track at all.So,when devices are underwater,the closed cycle using metal fuel is a practical ideal mode.This article has researched the different modes and crucial components of MFCC through thermal performance calculation,numerical simulation.The brief contents are as follows.Firstly,thermal performances of alternative fuels and corresponding oxidants were calculated.Basing on the comparison of the inter-combination of Li,Na,K,Mg,Al and O₂,SF₆,results showed that Li performed best.Basing on the comparison of the inter-combination of Li and F₂,Cl₂,O₂,SF₆,ClF₃,results showed that the combination of Li and SF₆ performed best.The specific energy of the combination is 14.47MJ/kg and the energy density is 15.24MJ/kg.Next,simulation models of the Closed Brayton Cycle which use Li/SF6 as heat sources were founded.CO2,air,He and SF6 for the Closed Brayton Cycle.The analyses of the pressure ratio,turbine inlet temperature,massflow rate,and the massflow rate and pressure of compressor-inlet showed that He was the best selection on Brayton.The comsuption of Li could be as low as 5-9g/s and lower than other fuels conspicuously.Finally,basing on the Closed Brayton Cycle using Li/SF₆ as heat source and He as cycle fluid,the structures of heat exchangers for heating and cooling has been accomplished.The so-called spiral-tube heat exchanger mode was used on both items.The results of numerical simulation showed that,heater's coefficient of heat transfer is 103.56±0.01 w/?m²·??.When the temperature of heat source was 1000K,the temperature rise was 600K.Cooler's coefficient of heat transfer is 161±0.5 w/?m²·??,the temperature can be reduced to 320K.Area of allowance of heat exchangers was 10%.Design requirements has been satisfied.