JET INTERACTION TEST PROGRAM (CCN NO. 39).
Engineering Analysis technical note no. 30,
PHILCO RESEARCH LABS NEWPORT BEACH CALIF
Pagination or Media Count:
An experimental and theoretical investigation was conducted to study the jet impingement forces on a right circular cylinder in the flow field of a rocket nozzle exhausting into a vacuum or near-vacuum environment. In the theoretical investigation, an approximate method based on radial flow of the exhaust jet and a Newtonian approximation was developed to predict the jet impingement forces on a cylinder in a vacuum. The experimental investigation was performed in the Aeronutronic high-altitude chamber to determine the jet impingement forces and pressures on two instrumented cylinder models. Unheated nitrogen gas was exhausted from a conical nozzle into the test chamber at a nominal starting altitude of 250,000 feet. Six positions of the cylindrical models relative to the nozzle exit were investigated. In general, results of the experimental investigation indicate that the forces measured under essentially vacuum conditions are applicable to the case of a pure vacuum environment. Good agreement was obtained between the experimental force results and the theoretical results. The experiments also indicate that the decrease in altitude during testing because of the addition of mass from the nozzle can have a significant effect on the jet impingement force. Author