预混火焰面附近的湍流特性测量

为考察预混火焰面附近的湍流特性,以及湍流与化学反应相互作用的机理,采用激光多普勒技术(laser Doppler anemometry,LDA)对本生火焰和V型火焰的流场进行了诊断。分别通过固体粉末和雾化硅油液滴进行无条件和条件示踪,研究了全场及反应物来流的流动特性。无条件示踪的测量结果表明,火焰区的流场存在湍流度迅速增大然后衰减的现象,而速度的测值呈现双峰分布。条件示踪测量结果表明,在火焰区内反应物来流的流动特性并没有发生明显的改变。在剪切流场中,火焰面的脉动和皱褶不显著影响上游反应物的流动特性。

Measurement of turbulent flow characteristics adjacent to a premixed flame sheet

The flow fields adjacent to a Bunsen flame and a V-type flame were analyzed to study the turbulence characteristics of the flow field and the interactions between the turbulence and the flames. The velocties in the reacting flow field were measured using laser Doppler anemometry (LDA). Seeding for the unconditioned velocity measurements was provided by refractory solid particles. The conditioned velocity measurement, which traced only the reactant flows, was made possible by using a silicon oil aerosol as the LDA seed. The unconditioned measurements revealed that the probability density function (PDF) of the measured velocities has a two-peak distribution, while the conditioned measurements showed that the turbulence characteristics of the reactants within the flame zone remain almost the same as that of the upstream flow steam. The results demonstrate that the premixed flame sheet has negligible influence on the incident flow characteristics.