Investigating the Influence of Tailored Wall Temperature Profiling on Hypersonic Boundary Layer Transition
Abstract
Understanding the mechanisms contributing to the transitioning of the hypersonic boundary layer to turbulence is an active and ongoing area of research as this has tremendous impact on the design of future hypersonic vehicles. It is well established that the transition region in hypersonic flows can often have the highest heat loading thus making it necessary to be able to predict where along the surface of a hypersonic vehicle this phenomenon will occur. The success of the recent Boundary Layer Turbulence (BOLT II) flight experiment over a swept leading-edge wedge model with a concave surface will provide a strong impetus to better understanding the transition and turbulent boundary layer growth phenomena. As a part of the BOLT II team, we are presently investigating the heating of the model over its flight trajectory and aiming to undertake ground tests in the T4 Stalker tube high-enthalpy facility under flight-matched conditions. And, in a recently concluded AFOSR funded project we demonstrated the transition occurring more upstream over a heated flat plate. In this proposal, we would like to expand on these two works further into an investigation of the role of the wall temperature in delaying or accelerating transition. Zaki et al, numerically show that the tailoring of wall heat fluxes can delay transition in a Mach 4.5 flow over a flat plate. However, hypersonic flow activates different second mode frequencies and is not expected to be as influenced by first mode disturbances as indicated in Zaki’s high supersonic test case. Therefore, in this project we will explore in detail how and when hypersonic boundary layer transition can be altered compared to an unheated-uncooled wall temperature case as well as a uniformly heated-cooled wall temperature case. We will develop the work in two stages- First, we will examine with various patterned-controlled wall temperature profiles how transition is influenced in hypersonic flow fields over a canonical geometry such as a flat plate. Next, we will investigate how these findings alter when we encounter a three-dimensional body such as the BOLT II geometry. We will examine both the flat BOLT II and the normal BOLT II models to further delineate effects of just adding a swept leading edge and then the concave curvature along with wall heating-cooling. In studying this phenomenon, we will employ a suite of surface sensors (in-house heat transfer gauges, custom made Kapton backed thin film heat transfer gauges, PCB high-frequency and kulite pressure sensors) and optical measurements (high-speed IR thermography, TDLAS and CFLDI measurements). We will aim to utilize the T4 Stalker tube as the main facility for the investigations and complement it with a few select test runs in the X3R facility housed in the secure hypersonic precinct and aim to study the effects of scaling there. We will judiciously utilize our in-house hypersonic flow solver Eilmer- RANS to guide the development of experiments. simulations of select configurations to compare against the experimental data and to further interrogate the interplay of various physical mechanisms in a heated-cooled hypersonic boundary layer and their influences on transition.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 16, 2024
- Source ID
- FA23862314088
Entities
People
- Ananthanarayanan Veeraragavan
Organizations
- Air Force Office of Scientific Research
- United States Air Force
- University of Queensland