ACCELERATION AND INJECTION EFFECTS ON LONGITUDINAL VORTICES IN CONCAVE WALL BOUNDARY-LAYERS


UMUR H. , CRANE R., WHITELAW J.

PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE, vol.209, no.1, pp.1-10, 1995 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 209 Issue: 1
  • Publication Date: 1995
  • Doi Number: 10.1243/pime_proc_1995_209_116_02
  • Title of Journal : PROCEEDINGS OF THE INSTITUTION OF MECHANICAL ENGINEERS PART C-JOURNAL OF MECHANICAL ENGINEERING SCIENCE
  • Page Numbers: pp.1-10

Abstract

Measurements of longitudinal velocity and wall temperature have been obtained in a wind tunnel with a concave wall, with momentum thickness Gortler numbers from 5 to 10 at the initial station. Vortex generators were used to enhance the vortex structure in flow with zero streamwise pressure gradient, Spanwise variations existed over a limited range which is quantified. It is shown that mild acceleration amplified the vortices and enhanced the regularity of the spanwise variation; strong acceleration, with velocity gradient parameter K near 2 x 10(-6), suppressed them and limited the growth in spanwise-averaged Stanton number. The influence of favourable pressure gradients was confirmed in a curved water channel with similar Gortler numbers. Discrete hole wall jets with varying jet-to-free-stream velocity ratios were used in the water channel to examine the response of longitudinal vortices to a spanwise-periodic disturbance of different wavelengths. The wall temperature characteristic of the jets persisted for a considerable streamwise distance with velocity ratios of 0.4 and unity, while a distribution nor dissimilar to that without blowing was found at all stations with a velocity ratio of 15.