Transverse and parallel injection of hydrogen with supersonic combustion in a shock tunnel

An experimental comparison has been made of the combustion induced pressure rise in a constant area duct when hydrogen is injected transverse to the flow by using a surface orifice, and when it is injected parallel to the flow by using a central injection strut. The experiments were conducted in a shock tunnel at a flow Mach number of 4.2 and stagnation enthalpies of 5.6, 6.5 and 8.9 MJ kg. Both room temperature and heated hydrogen were injected, and a method of heating the hydrogen by compression in a gun tunnel which was slaved to the shock tunnel is described. It was found that, for both unheated and heated hydrogen, the combustion pressure rise was not measurably dependent on the method of introducing the hydrogen, not withstanding the complicated shock related flow pattern arising from transverse injection. Received August 14, 1995 / Accepted February 14, 1996