OVERVIEW
Our research focuses on the various problems of aerothermodynamics in the high-speed flight. Shock-wave/shock-wave and shock-wave/boundary-layer interactions typified by the high-speed aerodynamic interactions, a hypersonic boundary-layer transition, an optical flow diagnostics of Temperature-Sensitive-Paint (TSP) and Pressure-Sensitive-Paints (PSP) and high-speed schlieren for the transient measurements, are our main research projects. Our Lab has also national and international collaborations, please visit the following link to a cooperating Partners.
High-Speed Aerodynamic Interactions
Aerodynamic interactions in high-speed flows causes severe heating loads with flow unsteadiness. Such the situations are observed in Scramjet engine intake and cowl, Body flaps and so on. Shock-wave/shock-wave and shock-wave/boundary-layer interaction (see below images) increase in pressure and heat flux. We focus on the investigation of the mechanism of the unsteadiness using high-speed schlieren technique and the estimation of accurate measurement of instantaneous pressure and temperature using optical flow diagnostics.
Boundary-Layer Transition in High-Speed Flows
Boundary-layer transition from laminar to turbulent in hypersonic speeds causes a severe heating loads as well as drastic increase in friction drag (see below TSP image obtained at DLR). The boundary-layer instability in hypersonic flow known as the second mode or Mack mode are not well matured research area, and an approach for understanding the mechanism of the transition process in experiment is not straightforward because of the high frequency phenomena and the experimental environment of high enthalpy or shock-induced flows. We are now challenging to the difficulty by the novel optical flow diagnostics.
Advancing Optical Flow Diagnostics
Research and development of the novel optical flow diagnostics of Temperature-Sensitive-Paints (TSPs) and Pressure-Sensitive-Paints (PSPs) and high-speed schlieren technique are one of our main research topics. TSP/PSP known as the non-intrusive two-dimensional temperature and pressure measurements are at the phase of application to unsteady fluid phenomena. Our strong point in these measurements is the ultra-fast response time, the TSP has been applied for the basic researches such as the unsteady aerodynamic phenomena in the shock-tube, the shock-wave/boundary-layer interactions, hypersonic boundary-layer transitions, also the validation and the design of the scramjet (supersonic-combustion ramjet) engine intake and the small-scale hypersonic vehicles. High-speed schlieren technique can clarify the mechanism of unsteady fluid phenomena that was difficult to understand because it could not be visualized, and is thus indispensable as unsteady visualization. Capture the instantaneous fluid phenomena accurately and clearly leads to a deep understanding of unsteady fluid motion, resulting in a good design of future flying vehicles.
Free-Flight Measurement
In most cases, the experiment for the test article in wind-tunnel test bed is carried out through a sting or a strut to keep the position. However, these supports disturb the flow around the test article, especially, which makes it difficult to reproduce wakes behind the article. In Free-Flight Measurement (FFM), the test article flies freely in the wind tunnel with no disturbance due to the support on measurements after wind tunnel start-up, where ideal flow condition can be realized. FFM enables various measurements typified by the force and moment measurements through high-speed visualization techniques.