大速差射流燃烧室内三维湍流气固两相流的实验研究

EXPERIMENTAL RESEARCH ON 3D TURBULENT GAS-PARTICLE FLOWS IN A COMBUSTOR OF CO-FLOW JET WITH LARGE VELOCITY DIFFERENCE

本文用二维激光多普勒测速仪和探针取样法对大速差射流燃烧室中冷态三维湍流气固两相流动进行了实验研究,测量了气相速度,颗粒速度、颗粒质量流分布及两相各自的湍流特性,探讨了高速射流作用下两相流场的主要物理特征及其对火焰的稳定和强化燃烧的作用。

The time-averaged and root-mean-square fluctuation velocities of gas and particle phases and particle mass flux distributions have been measured by a 2-dimen-sional laser Doppler velocimeter combined with a sampling probe in a combustor of co-flow jets with large velocity difference. The results show large velocity slip between gas and particle phases. The gas-phase flow has astrong reverse flow in the near-axial region, while particles keep their forward motion almost everywhere, even in the strongly reverse flow region. The particle mass flux distributions measured have their maximum values in the near-axial reverse flow region. Presence of high-velocity jets remarkably enhances particle mixing. All these facts reveal the mechanism of flame stabilization and combustion intensification in the combustor of co-flow jets with large velocity difference. The four peaks of gas turbulence intensity observed in experiments demonstrate that the turbulence is caused by large velocity gradient resulted from sudden expansion and high velocity jets.Particle turbulence intensity has the similar behaviour as gas one,but the former is not always smaller than the latter. This means that the classical Hinze-Tchen's theory of particle following gas motion must be reexamined.