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Experimental Investigations of Leading Edge Bluntness in Shock Boundary Layer Interactions at Hypersonic Speeds

Electronic Theses of Indian Institute of Science

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Title Experimental Investigations of Leading Edge Bluntness in Shock Boundary Layer Interactions at Hypersonic Speeds
 
Creator Lakshman, Srinath
 
Subject Hypersonic Speeds
Shock Boundary Layers
Shock Boundary Layer Interaction
Hypersonic Shock Tunnel 2 (HST2)
Schlieren Visualisations
Shock-shock Interactions
Shock Polars
Free Interaction Theory
Aerospace Engineering
 
Description Shock Boundary Layer Interactions (SBLIs) and shock-shock interactions are some of the most fundamental problems in high speed aerodynamics. These interactions are of particular importance in scramjet intakes at hypersonic speeds. In hypersonic own with strong SBLI accompanied by own separation, large separation bubbles can form due to high impinging shock strengths. While experiments involving large separation lengths for the impinging shock boundary layer interactions near sharp leading edge are well documented in the literature, only few investigations on the effect of leading edge bluntness on the interactions are studied. In the present study, experiments were carried out to study the role of leading edge bluntness on the impinging shock boundary layer interactions. An oblique shock generated by a wedge (wedge angle 31 degrees) is made to impinge on a at plate (length 200 mm) over which a boundary layer develops. Different leading edge inserts were used on a at plate to get either a sharp or a blunt (radii from 2 to 8 mm) leading edge. The position of the at plate was moved horizontally with respect to the wedge to vary the shock impingement location relative to the leading edge. Experiments were carried out at two freestream conditions - Mach 5.88 (total enthalpy of 1.26 MJ/kg and freestream Reynolds number of 3.85 million per meter) and Mach 8.54 (total enthalpy of 1.85 MJ/kg and freestream Reynolds number of 1.41 million per meter). The various features of the interaction along with different parameters were obtained from schlieren visualizations and surface pressure measurements. The schlieren visualization was used to obtain the separation length, while the reattachment pressure was obtained from the surface pressure distribution. From the present experimental study, a reduction in separation length was observed with an increase in leading edge bluntness. It was also seen that the sharp leading edge had the maximum separation length. Correlations for the separation length and the reattachment pressure have been proposed for these experimental conditions. Numerical simulations were also carried out using commercial software and they had a qualitative agreement with the experiments.
 
Contributor Jagadeesh, G
 
Date 2018-07-20T07:19:54Z
2018-07-20T07:19:54Z
2018-07-20
2015
 
Type Thesis
 
Identifier http://etd.iisc.ernet.in/2005/3865
http://etd.iisc.ernet.in/abstracts/4737/G27112-Abs.pdf
 
Language en_US
 
Relation G27112