Transient Pressure-Sensitive-Paint Investigation in a Nozzle.

This paper presents an application of the pressure-sensitive-paint technique under unsteady flow conditions. Anodized-aluminum pressure-sensitive-paint coating was used to investigate the flowfield inside a nozzle during the transient phase and to assess the pressure gradient at the outlet region during the steady-state phase. The anodization procedure was adjusted to apply anodized-aluminum pressure-sensitive-paint coating on a large three-dimensional model. The images were acquired using a fast-frame-rate camera up to 5000 images per second, which allows accurate imaging of the paint, for which the response time is below 200 ms. Discrepancies between pressure-sensitive- paint results and pressure measurements obtained with Kulite sensors are due to a temperature effect and to condensation of the exhaust air, which modifies the optical path between the observed surface and the camera. [ABSTRACT FROM AUTHOR]