High temperature hydrogen supply technique for supersonic combustion pulse facility

The high temperature hydrogen supply system used to feed the CNR-TEMPE supersonic combustion tunnel is described. Hydrogen temperature can be raised up to about 1000 K by ohmic heating of the duct connecting reservoir to injector. A method for evaluating the actual hydrogen injection temperature is devised and design criteria of the injection setup allowing constant equivalence ratio during the supersonic combustion tests are given. Experimental data concerning the cooling rate of high temperature hydrogen as it flows in cold ducts are presented. Such data show that hydrogen temperature decreases quickly and that, when possible, the injector itself should be heated to prevent excessive temperature drop.