Two-colour laser-induced fluorescence (LIF) of toluene has been demonstrated to provide in situ, spatially resolved, planar measurements of the gas-phase temperature in a particle-laden flow with strong radiative heating at fluxes up to 42.8 MW/m². Toluene was seeded in trace quantities into the gas flow laden with particles of mean diameter 173 μm at a volumetric loading sufficiently high for particle–fluid and particle–particle interactions to be significant. The particle number density was also measured simultaneously using Mie scattering. The two-colour LIF method was found to resolve temperature with a pixel-to-pixel standard deviation of 17.8 °C for unheated measurements in this system despite significant attenuation of the probe laser and signal trapping of the fluorescence emissions from the densely loaded particles. Following heating of the particles using high flux radiation, the increase in the gas-phase temperature from convection was found to be spatially non-uniform with highly localised regions of temperature spanning from ambient to 150 °C. This gas-phase heating continued well downstream from the limits of the region with radiative heating, with the time-averaged gas temperature increasing with distance at up to 2,200 °C/m on the jet centreline. The temperature of the flow was non-symmetrical in the direction of the heating beam, because the particles attenuate the radiation through absorption and scattering. The addition of radiation at fluxes up to 42.8 MW/m² did not significantly change the particle number density distribution within the region investigated here.

Graphic abstract

中文翻译：

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一种新方法的见解，该方法可在高通量辐射下对负载颗粒的流中的气相温度进行单次平面测量

经证明，甲苯的双色激光诱导的荧光（LIF）可以在载流量高达42.8 MW / m ^2的强辐射加热下，对载有颗粒的气流中的气相温度进行原位，空间分辨的平面测量。。甲苯以痕量注入到载有平均直径173μm颗粒的气流中，其体积负载足够高，以使颗粒-流体和颗粒-颗粒之间的相互作用显着。还使用米氏散射同时测量了颗粒数密度。尽管探针激光的显着衰减和来自密集负载颗粒的荧光发射的信号捕获，发现该系统的两种颜色的LIF方法仍可解决该系统中未加热测量的像素间标准偏差为17.8°C的温度。使用高通量辐射加热颗粒后，对流引起的气相温度升高在空间上是不均匀的，局部温度范围从环境温度到150°C不等。这种气相加热继续在辐射加热区域边界的下游继续进行，时间平均气体温度随射流中心线上的距离增加，最高可达2200°C / m。流的温度在加热束的方向上是不对称的，因为颗粒通过吸收和散射使辐射衰减。通量高达42.8 MW / m的辐射量增加^图2没有显着改变此处研究的区域内的颗粒数密度分布。

图形摘要