Application of Pressure Sensitive Paint -Theory and Pratice-

Abstract

For investigations of pressure distributions on wind tunnel model surfaces with high spatial resolution new experimental techniques, such as Pressure Sensitive Paint (PSP) are required which allow to obtain pressure distributions on different model sizes in various speed ranges. Spatial structures and/or rapid temporal or spatial changes of aerodynamic phenomena (transition from laminar to turbulent flow, coherent structures, pitching airfoils in transonic flows with shocks, rotors, test facilities with short run time and different flow temperature etc.) can be investigated using the non- intrusive optical pressure measurement technique. An important feature of PSP is that for the first time, a reliable basis of experimental static pressure data is provided for direct comparison with conventional pressure taps for accuracy comparison and with numerical calculations for validation of computer codes. During the last years an increasing number of scientists have started to utilize the PSP technique to investigate pressure distributions from low speed up to hypersonic and cryogenic wind tunnels as well as high temperature flows i.e. in turbo machines. The PSP technique also expands from steady to periodic and unsteady phenomena to study the instantaneous structure of pressure fields in various areas of fluid mechanics. A number of different approaches for paint development, recording and evaluation of PSP images have been described in literature. This course, which is the first one on PSP organized by DLR Göttingen, Germany, will mainly concentrate on both, industrial measurement techniques as well as aspects of the theory of PSP relevant to applications. Besides giving lectures on the fundamental aspects, special emphasis is placed on the presentation of practical and reliable solutions of problems which are faced during the implementation of this technique in wind tunnels and other test facilities. During practice the participants will have the opportunity during this course to carry out the recording and the evaluation of PSP images by themselves in small groups. Recent developments of the PSP technique such as single and multiple component paints (one CCD camera for one pressure sensitive molecule, camera systems for binary paints, and 360° PSP systems for calculation of forces and moments) will be discussed and demonstrated.