Operation and Performance of a Shock Tube with Heated Driver

A shock tube was constructed with a driver section which could be heated with "Calrod" heaters to temperatures of approximately 300°C. This temperature rise increased the shock wave Mach number by about 40 per cent, or from values of 7.7 to 10 for pressure ratios of 2O,000 across the diaphragm. This increase is sufficient to produce partial dissociation of the oxygen molecules behind the shock wave. The flow behind the shock wave was as uniform as that produced by an unheated driver. A transition section was designed to enable the major portion of the low pressure chamber to be constructed of round Shelby tubing, while the test section still had a flat top and a flat bottom. The flat surfaces are advantageous for optical studies and for convenience in instrumenting the tube. Despite the fact that the transition was gradual, disturbances were present in the flow in the test section, 18 inches downstream of the transition section.