TRANSVERSE AND PARALLEL INJECTION OF HYDROGEN WITH SUPERSONIC COMBUSTION IN A SHOCK TUNNEL

An experimental comparison has been made of the combustion induced pre ssure rise in a constant area duct when hydrogen is injected transvers e to the flow by using a surface orifice, and when it is injected para llel to the flow by using a central injection strut. The experiments w ere conducted in a shock tunnel at a flow Mach number of 4.2 and stagn ation enthalpies of 5.6, 6.5 and 8.9 MJ kg(-1). Both room temperature and heated hydrogen were injected, and a method of heating the hydroge n 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 met hod of introducing the hydrogen, not withstanding the complicated shoc k related flow pattern arising from transverse injection.