Presidential Young Investigators Award: Combustion in Boundary Layers and Particle-Laden Flows

该PYI奖的主要研究领域是光学诊断在实际工程系统中测量的应用，涉及液滴和颗粒负载流中的燃烧。具体的重点是发展非侵入式光学方法来研究两相流边界层中的粒子输运、传热和质量输运。燃烧液滴的直径通常为0.2毫米，周围是一个2毫米的包络火焰。最强大的光学探针之一是基于激光的相干反斯托克斯散射气体分子在直径约0.1毫米，2毫米长的圆柱形体积；因此，要将这种方法应用于液滴火焰，探针体积必须减小一个数量级。本文将探讨实现空间分辨率提高的方法。光学诊断非常适合边界层测量，因为典型的边界层对物理探针引起的扰动很敏感。然而，由于边界层的物理尺寸要求极高的空间分辨率，光学诊断的应用是困难的。研究将围绕这一问题展开，并将其应用于内燃机固体表面的传热、熔融金属喷雾中的快速凝固、表面上的颗粒磨损和沉积以及超音速流动中的边界层传热。

The principle areas of research involved in this PYI award are the application of optical diagnostics for measurements in practical engineering systems involving combustion in droplet and particle laden flows. The specific focus is on the development of non-intrusive optical methods to study particle transport, heat transfer, and mass transport through boundary layers in two-phase flows. A burning droplet is typically 0.2 mm in diameter surrounded by a 2 mm envelope flame. One of the most powerful optical probes is based upon the coherent anti-Stokes scattering of laser light by gas molecules within a cylindrical volume about 0.1 mm in diameter by 2 mm long; so that to apply this method to droplet flames the probe volume must be reduced an order-of-magnitude. Methods to accomplish this increase in spatial resolution will be explored. Optical diagnostics are ideally suited to boundary layer measurements because typical boundary layers are sensitive to perturbations caused by physical probes. Application of optical diagnostics is difficult, however, because the physical dimensions of the boundary layer require extremely high spatial resolution. The research will be centered on this problem, with applications to heat transfer to solid surfaces in combustion engines, rapid solidification in molten metal sprays, particle attrition and deposition on surfaces, and boundary layer heat transfer in supersonic flows.