Experimental and Fundamental Analysis of Flow in Corners: Favorable and Adverse Pressure Gradients

Abstract

Three dimensional instantaneous velocity data were taken in a turbulent corner flow with smooth walls under zero, a favorable, and an adverse pressure gradient. The favorable pressure gradient was −26.5 Pa/m (K = 0.15E−6) and the adverse gradient was 34.9 Pa/m (K = −0.20E−6). This paper will concentrate on effects of the favorable and adverse pressure gradients. Zero pressure gradient results were published in an earlier manuscript [1]. Experiments were carried out in air with a free stream inlet velocity of 13 m/s and an axial Reynolds number of about one million. The data were collected using a three-component LDV system that was configured in a nearly orthogonal setup. Measurements were made down to a y+ of approximately 5, and should provide a valuable data set in developing models and predictive codes. Data were collected at two axial locations, 0.93 and 1.26 m measured from the virtual origin. The boundary layer thickness was 20.90 mm and 24.91 mm respectively at these locations for the zero gradient case. The favorable gradient had thicknesses of 19.35 mm and 22.53 mm respectively, whereas the thicknesses of adverse pressure gradient were 28.89 mm and 36.81 mm. At each position, instantaneous velocity profiles were measured at 6.35, 12.7, 20.6, 41.2, 82.3, 121.9, 164.5, 184.8, and 205.1 mm from the corner. The centerline profiles agree well with classical flat plate data. Three mean velocity and six Reynolds stress components have been calculated. The instantaneous velocity field data set is sufficient to compute higher order correlations. The data will be very valuable for development of computer codes and models for corner flows of all kinds and for heat transfer studies in the internal cooling channels of gas turbine blades and turbine end wall flow. An analysis of the data is presented and will provide a detailed database for this complex three dimensional flow fields.