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 set- up 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, � , momentum thickness, , and skin friction coefficient, Cf
Highlights
The apparatus is recommended to have a longitudinal fluctuation level less than 0.1% in the streamwise direction and less than 0.2% in the spanwise and wall-normal direction, it is clear that the turbulence level average in the duct is approximately 1.5%
The complication appears when the bottom wall of the apparatus is used as a flat plate model that the origin of this geometry
In case of using a blunted flat plate or a sharp flat plate at negative angle of attack at the middle of the test section, the expected errors obtained is about 20-30% in streamwise direction and 10-15% errors in Rex [17]
Summary
It is known that transition in boundary layer that flows in turbomachines and aerospace devices is affected by various parameters, such as freestream turbulence, pressure gradient and separation, Reynolds number, Mach number, turbulent length scale, wall roughness, streamline curvature and heat transfer. Due to this variety of parameters, there is no existing mathematical model that can predict the onset and length of the transition region. The objective of the present work is to evaluate experimentally the capability of a new apparatus designed for conducting experiments of transitional boundary layer flows over a flat plate with zero pressure gradient
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
