Separation Characteristic of Turbulent Steady Flow Around an Obstacle Placed in a Square Duct

Abstract

Experimental Investigation has been carried out on turbulent flow around an obstacle placed on the lower wall of a square duct. Particular emphasis is placed on the velocity distribution of turbulent flow, the reattachment length, and the static pressure distribution on the upper wall of the duct. Two types of obstacles are used: a backward-facing step and a diffuser-like constriction. A flow visualization method is used for measuring the velocity distribution and reattachment length. Soap bubbles are used as the tracer. A pressure transducer is used for measuring the static pressure distribution. A blockage factor is introduced to correlate the static pressure distribution. The reattachment length depends strongly on the shape and size of an obstacle. An empirical equation is proposed for the reattachment length.