Visualizing Strake and Wing Vortices in Supersonic Flow by a Thermographic Technique

Article type: Research Article

Authors: Zuppardi, G. | Valenza, F.

Affiliations: Università di Napoli "Federico II", Dipartimento di Scienza ed Ingegneria dello Spazio "Luigi G. Napolitano", P.le V. Tecchio 80, 80125 Napoli, Italy

Abstract: The Unsteady Computerized Thermographic Technique (UCTT) provides patterns of the Stanton number on a body surface. These patterns are the imprints of the flow field. The UCTT already proved to be a powerful, not intrusive diagnostic tool both for the visualization and the strength evaluation of vortical structures on the lee-side surface of delta wing models. The patterns are obtained by processing, by an "ad hoc" mathematical model, the temperature time evolution of the model surface. The temperature is measured at a distance by a thermocamera. In previous tests on delta wing models, the used thermocamera showed a limitation in the optics and did not provide an appropriate space resolution and, therefore, a detailed visualization of whole vortical structure. In the present paper this limitation has been overcome. The optics improvement has doubled the space resolution of thermocamera. Tests, made at angle of attack of 6-deg. and Mach number of 1.92, verified that this improvement was substantial. In fact, the detection of secondary vortex on delta wing model and strake vortices on a double delta wing model was made possible. Unfortunately, it was not possible to visualize details of vortical structure on a Gothic wing model. Tests showed that vortical patterns were similar to the one on delta wing model.

Keywords: flow visualization, infrared thermography

Journal: Journal of Visualization, vol. 2, no. 1, pp. 59-71, 1999