An experimental study of sweep angle effects on the transition point on a 2D wing by using hot-film sensor

Abstract

Paper presented at the 9th International Conference on Heat Transfer, Fluid Mechanics and Thermodynamics, Malta, 16-18 July, 2012.

Location of transition point over a 2-D swept wing was investigated. A series of wind tunnel tests were performed to predict the transition location over three models of swept wing having same aspect ratio, and at various angles of attack and sweep angles by hot-film anemometer. Two flat plates were used at the ends of the models to prevent the flow to roll up and to reduce the boundary layer effect of the test section on the models, but the flow field on the model was still 3D because of the swept angle effects that led to formation of cross flow over the wing surface. Due to the complexity of the calibration of the hot film sensors, as well as various sources of errors in the calibration process, the hot film sensors were not calibrated and their signal is qualitatively investigated. Data obtained from the hot film sensor signal indicates that as the swept angle increases, the position of transition moves toward the leading edge of the wing due to strengthening of the cross flow about the leading edge, and transition occurs at a smaller angle of attack. Increasing the angle of attack also moved the position of transition point closer to the leading edge of the wing. The transition line is approximately parallel to the x/c local line which may indicate that the strength of cross flow is nearly constant on each line parallel to the c/4 local line.