Abstract

Fine particles of ash and sand can deposit on the surfaces of cooling ducts, diminishing heat transfer efficiency and threatening the operation of turbine engines. The surface roughness of deposits can alter the nearby flow dynamics, and result in changes of subsequent particle collision and deposition. In this work, the effects of rib turbulence on particle deposition in cooling duct are numerically studied based on the wall modeled shear stress transport k–ω model with a UDF code correction for particle–wall impacts and the discrete particle model. A Gaussian probability density function is adopted to give the topology of deposited particles on the surface impacted by micron particles. We investigate how variables such as particle diameter and temperature impact collision and deposition processes. Additionally, the impact of ribbed turbulence on particle deposition is also discussed. The findings indicate that the impact ratio increases with particle diameter while exhibiting less sensitivity to temperature. Deposition ratios experience a significant decrease when particle size exceeds 1 μm. The temperature of the particles has a noteworthy influence on surface profile of deposits. Specifically, deposits on the wall surface, where particles are introduced by fluid injection, tend to assume a crane-like shape as the temperature rises. Notably, a more uniform deposition pattern is achieved when the particle temperature is low. In terms of particle distribution, low-velocity particles are more likely to accumulate in the windward region of the rib, especially at the junction of the rib wall, where the maximum deposition height is observed. Furthermore, deposits on the rib surface tend to grow, and the gap between the peak and valley widens as the particle temperature increases, as evident from the roughened rib surface features.

中文翻译：

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用高斯概率密度模型模拟内部冷却管道中微米砂粒的表面沉积

摘要

灰尘和沙子的细颗粒会沉积在冷却管道的表面上，降低传热效率并威胁涡轮发动机的运行。沉积物的表面粗糙度可以改变附近的流动动力学，并导致随后的颗粒碰撞和沉积的变化。在这项工作中，基于壁模拟剪切应力传递k-ω模型（具有针对颗粒壁冲击的 UDF 代码校正）和离散颗粒模型，对冷却管道中的肋湍流对颗粒沉积的影响进行了数值研究。采用高斯概率密度函数给出微米粒子撞击表面上沉积粒子的拓扑结构。我们研究颗粒直径和温度等变量如何影响碰撞和沉积过程。此外，还讨论了肋状湍流对颗粒沉积的影响。研究结果表明，冲击比随着粒径的增加而增加，同时对温度的敏感性较低。当颗粒尺寸超过 1 μm 时，沉积率显着下降。颗粒的温度对沉积物的表面轮廓具有显着的影响。具体来说，随着温度升高，通过流体注入引入颗粒的壁表面上的沉积物往往会呈现起重机状的形状。值得注意的是，当颗粒温度较低时，可以获得更均匀的沉积图案。从颗粒分布来看，低速颗粒更容易积聚在肋的迎风区域，特别是在肋壁交界处，沉积高度最大。此外，随着颗粒温度的升高，肋表面上的沉积物趋于生长，并且峰和谷之间的间隙变宽，这从粗糙的肋表面特征可以明显看出。