渦誘起ジェットによる円すいディフューザ内はく離流の制御
1997 年 63 巻 605 号 p. 82-87
詳細
1997 年 63 巻 605 号 p. 82-87
The aim of the present study is to clarify the applicability of vortex generator jets (VGJs) in the control of flow separating in a conical diffuser. Systematic experiments were made to investigate longitudinal streamwise vortices induced by eight jets issued from the wall of a circular pipe having 125 mm dia., where VGJs of 6 mm dia. pitched at 30 deg and skewed at 90 deg. The distributions of wall friction show that turbulent mixing in the boundary layer is enhanced by corotating type VGJs. By using a typical VGJ which was installed at the inlet of a 14 deg conical diffuser with an area ratio of 2.56, the separation in the diffuser was almost suppressed, and the pressure recovery coefficient increased from 0.63 to 0.68 at a velocity ratio Vj/U of 1.9. To quantify the structure of flow separating in a diffuser, attempts were made to measure the fraction of backflow with an X-type hot-wire velocimeter.
