Thermo-flow control using photon-matter interaction
Ultra high-speed thermo-flow control is a key technology in improving the energy efficiency and performance of various energy transportation systems. This type of control cannot be accomplished with conventional mechanical devices. Photon-matter interaction is a process where photons (from light sources such as lasers) collide with various materials. By concentrating photons into a small area therefore generating high energy, ultrahigh-speed local thermo-flow disturbance can be triggered inducing various phenomena such as Rayleigh scattering, plasma, and laser-induced breakdown (LIB). Utilizing these phenomena, increasing reactivity, or controlling phase change can be achieved to improve the efficiency and performance of mechanical systems.
We have conducted a high temporal resolution Rayleigh scattering technique which utilizes photon scattering from gas molecules, to obtain temperature information in high-pressure premixed methane combustion (Figure 1).
Figure 1. Experimental setup for Rayleigh scattering measurements in high-pressure combustion chamber.
Particle dispersion control can be achieved by inducing laser-induced breakdown (LIB) in air. LIB can be induced by focusing a pulsed laser, as shown in Figure 2 (a). The ensuing shockwave and related flow phenomena can be observed by the Schlieren method, as depicted in Figure 2 (b). Particles floating in the air are redistributed by the shockwave and the ensuing flow structure. Therefore, distribution of particles in the air can be controlled using LIB. This can be applied to various fields, such as semiconductor cleaning and particle transport, because it can control local particle distributions.
Figure 2. Experimental setups for (a) laser-induced breakdown and particle distribution measurement, and (b) high-speed Schlieren measurement for observing shockwave propagation.