Hot flow testing of dual bell nozzles

Kurzfassung

The dual bell nozzle offers a simple and efficient altitude adaption through its contour inflection, which insures a symmetrical and controlled separation at sea level and a large area ratio at high altitude. The conditions for the flow transition from one operating mode to the other have been intensively investigated in cold flow conditions. A test campaign has been conducted on two dual bell nozzle geometries to verify the theoretical prediction criterion and to investigate the influence of the temperature variations. Therefore, a thin walled axisymmetric and a planar nozzle were designed and tested under hot flow conditions. Wall temperature measurements have been made using both thermocouples and thermal imaging. The region of the contour inflection was of particular interest for the evaluation of thermal behavior in the nozzle wall.