Periodic Unsteady Flow Aerodynamics and Heat Transfer: Studies on a Curved Surface, Combined Part I and II

Abstract

Aerodynamic and heat transfer investigations were done on a constant curvature curved plate in a subsonic wind tunnel facility for various wake passing frequencies and zero pressure gradient conditions. Steady and unsteady boundary layer transition measurements were taken on the concave surface of the curved plate at different wake passing frequencies where a rotating squirrel-cage generated the unsteady wake flow. The data were analyzed using timeaveraged and ensemble-averaged techniques to provide insight into the growth of the boundary layer and transition. Ensemble-averaged turbulence intensity contours in the temporal spatial domain showed that transition was induced for increasing wake passing frequency and structure. The local heat transfer coefficient distribution for the concave and convex surface was determined at those wake passing frequencies using a liquid crystal heat transfer measurement technique. Detailed aerodynamic and heat transfer investigations showed that higher wake passing frequency caused transition to occur earlier on the concave surface. Local Stanton numbers were also calculated on the concave surface and compared with Stanton numbers predicted using a differential boundary layer and heat transfer calculation method. On the convex side, no effect of wake passing frequency on heat transfer was observed due to a separation bubble that induced transition.

On the Physics of Flow Separation Along a Low Pressure Turbine Blade Under Unsteady Flow Conditions

“…Furthermore, the unsteady boundary layer data from the present and planned experimental investigations will serve to extend the intermittency based unsteady boundary layer transition model developed by Schobeiri and his coworkers [7,11,12] to the LPT-cases, where separation occurs on the suction surface at low Reynolds number at design and off-design points. Furthermore, the experimental results are intended to serve as a benchmark data for comparison with numerical computation using DNS, LES or RANS-codes.…”

“…However, the above investigations were not sufficient to draw any conclusion with regard to universal character of the relative intermittency function. Further detailed investigations of the unsteady boundary layer along a high Reynolds number turbine blade of the Space Shuttle Main Engine (SSME) by Schobeiri et al [9] and its subsequent analysis [10], [11], and [12] verified the universal character of the relative intermittency function. For this purpose, Schobeiri et al [9] utilized a conceptually different type wake generator, which is also used for the investigation presented in this paper.…”