An investigation has been conducted at conditions of zero ram and sea-level pressure to determine the effect of inlet temperature and humidity on turbojet-engine performance with injection of water and water-alcohol mixtures at the compressor inlet. The inlet-air temperature was varied by mixing atmospheric air with exhaust gases recovered from the exhaust jet of the engine, and the inlet humidity was varied by evaporating water in the exhaust gas used for heating the inlet air. It was found that at a given engine speed and tailpipe temperature, both the thrust and total mass flow for the complete range of compressor-inlet temperatures, composition of injected mixtures, and injected flows investigated were functions only of the compressor-pressure ratio. The pressure ratio, and hence the aug¬mented thrust, increased with injected flow and at a constant injected flow decreased with compressor-inlet temperature. The effect of inlet temperature on compressor pressure ratio and thrust became less pro¬nounced as compressor-inlet injected flow increased. The augmented thrust ratio increased with compressor-inlet temperature at a con¬stant total liquid flow. At a total liquid flow of 5 pounds per second, the augmented thrust ratio obtained at rated engine speed and tail-pipe gas temperature (as permitted by use of a variable-area exhaust nozzle) increased from 1.26 to 1.62 as the compressor-inlet temperature was increased from 60° F to 200° F. At a given inlet temperature and injection rate, the thrust decreased slightly with increasing humidity, the effects being more pronounced at the higher injection rates.
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