An Experimental Study of Fluctuating Pressure Loads Beneath Swept Shock/Boundary-Layer Interactions

An Experimental Study of Fluctuating Pressure Loads Beneath Swept Shock/Boundary-Layer Interactions
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
Total Pages: 28
Release: 2018-08-16
Genre:
ISBN: 9781725096882

A database is established on the fluctuating pressure loads produced on aerodynamic surfaces beneath 3-D shock wave/boundary layer interactions. Such loads constitute a fundamental problem of critical concern to future supersonic and hypersonic flight vehicles. A turbulent boundary layer on a flat plate is subjected to interactions with swept planar shock waves generated by sharp fins. Fin angles from 5 to 25 deg at freestream Mach numbers between 2.5 and 4 produce a variety of interaction strengths from weak to very strong. Miniature Kulite pressure transducers mounted in the flat plate were used to measure interaction-induced wall pressure fluctuations. These data will be correlated with proposed new optical data on the fluctuations of the interaction structure, especially that of the lambda-shock system and its associated high-speed jet impingement. Settles, Gary S. Unspecified Center NASA-CR-188919, NAS 1.26:188919 NAG1-1070...

An Experimental Study of the Sources of Fluctuating Pressure Loads Beneath Swept Shock/Boundary-Layer Interactions

An Experimental Study of the Sources of Fluctuating Pressure Loads Beneath Swept Shock/Boundary-Layer Interactions
Author: National Aeronautics and Space Administration (NASA)
Publisher: Createspace Independent Publishing Platform
Total Pages: 34
Release: 2018-06-30
Genre:
ISBN: 9781722068578

An experimental research program providing basic knowledge and establishing a database on the fluctuating pressure loads produced on aerodynamic surfaces beneath three dimensional shock wave/boundary layer interactions is described. Such loads constitute a fundamental problem of critical concern to future supersonic and hypersonic flight vehicles. A turbulent boundary layer on a flat plate is subjected to interactions with swept planar shock waves generated by sharp fins at angle of attack. Fin angles from 10 to 20 deg at freestream Mach numbers of 3 and 4 produce a variety of interaction strengths from weak to very strong. Miniature Kulite pressure transducers flush-mounted in the flat plate are used to measure interaction-induced wall pressure fluctuations. The distributions of properties of the pressure fluctuations, such as their ring levels, amplitude distributions, and power spectra, are also determined. Measurements were made for the first time in the aft regions of these interactions, revealing fluctuating pressure levels as high as 160 dB. These fluctuations are dominated by low frequency (0-5 kHz) signals. The maximum ring levels in the interactions show an increasing trend with increasing interaction strength. On the other hand, the maximum ring levels in the forward portion of the interactions decrease linearly with increasing interaction sweep back. These ring pressure distributions and spectra are correlated with the features of the interaction flowfield. The unsteadiness of the off-surface flowfield is studied using a new, non-intrusive technique based on the shadow graph method. The results indicate that the entire lambda-shock structure generated by the interaction undergoes relatively low-frequency oscillations. Some regions where particularly strong fluctuations are generated were identified. Fluctuating pressure measurements are also made along the line of symmetry of an axisymmetric jet impinging upon a flat plate at an angle. This flow was chos...

An Experimental Study of Fluctuating Wall Pressures in a Highly Swept, Sharp Fin-Induced, Mach 5 Shock Wave/Turbulent

An Experimental Study of Fluctuating Wall Pressures in a Highly Swept, Sharp Fin-Induced, Mach 5 Shock Wave/Turbulent
Author:
Publisher:
Total Pages: 150
Release: 1993
Genre:
ISBN:

Fluctuating wall pressure measurements have been made beneath the shock wave/turbulent boundary layer interaction generated by a sharp, unswept fin at angle of attack. Tests were conducted at Mach 5 with a freestream unit Reynolds number of 47.88 x 106 /m. The boundary layer developed naturally on the tunnel floor under approximately adiabatic temperature conditions. From visual inspection and standard time series analysis of fluctuating wall pressure signals, it has been shown that the separation shock wave undergoes a translating, intermittent type motion for fin angles between 16 and 28 degrees. Both the mean wall pressures and higher order moments are quasi-conically symmetric when collapsed in a conical coordinate system. Finally, the maximum wall pressure standard deviation in the intermittent region has been shown to scale with the sweep of the interaction and not with the inviscid pressure rise as has been previously suggested in the literature ... Shock wave, Boundary layer, Turbulent interaction, Interaction unsteadiness.

NASA SP.

NASA SP.
Author:
Publisher:
Total Pages: 590
Release: 1993
Genre: Aeronautics
ISBN:

Shock Wave-Boundary-Layer Interactions

Shock Wave-Boundary-Layer Interactions
Author: Holger Babinsky
Publisher: Cambridge University Press
Total Pages: 481
Release: 2011-09-12
Genre: Technology & Engineering
ISBN: 1139498649

Shock wave-boundary-layer interaction (SBLI) is a fundamental phenomenon in gas dynamics that is observed in many practical situations, ranging from transonic aircraft wings to hypersonic vehicles and engines. SBLIs have the potential to pose serious problems in a flowfield; hence they often prove to be a critical - or even design limiting - issue for many aerospace applications. This is the first book devoted solely to a comprehensive, state-of-the-art explanation of this phenomenon. It includes a description of the basic fluid mechanics of SBLIs plus contributions from leading international experts who share their insight into their physics and the impact they have in practical flow situations. This book is for practitioners and graduate students in aerodynamics who wish to familiarize themselves with all aspects of SBLI flows. It is a valuable resource for specialists because it compiles experimental, computational and theoretical knowledge in one place.