Experimental evaluation and set-up of a new apparatus designed for transitional flow experiments

Abstract

Experimental exercise has been conducted to validate the capability of a new test apparatus. The test stand has been designed and constructed at the laboratory of aerodynamics, University of Defence to carry out the experimental investigation of transitional flow prediction and development over flat plate. The test facility consists of a rectangular duct set on the suction side of air source apparatus. The working section is 2 m long with a cross section of 0.44 m in width and 0.25 m in height. The exercise is performed into two stages. In the first stage, the basic parameters such as freestream velocity, turbulence intensity and pressure gradient in streamwise direction were measured and manipulated to setup acceptable values. Second stage of the exercise, the bottom wall of the test section was used as a flat plate model to conduct turbulent boundary-layer experiment. The characteristics of the boundary layer obtained by using the apparatus are represented by a qualitative and quantitative agreement with those predicted by boundary-layer theory for turbulent boundary layer while more improvements seems to be required to satisfy the rules of boundary layer stability experiments. The results are show a fair agreement for mean velocity profile, U∞, boundary layer thickness, δ, momentum thickness, θ, and skin friction coefficient, Cf.

Keywords

• Transitional flow
• Turbulence intensity
• Transitional boundary layer
• Momentum thickness
• Skin friction coefficient