Abstract

Particle image velocimetry (PIV) has become a popular non-intrusive tool for measuring various types of flows. However, when measuring three-dimensional flows with two-dimensional (2D) PIV, there are some uncertainties in the measured velocity field due to out-of-plane motion, which might alter turbulence statistics and distort the overall flow characteristics. In the present study, three different turbulence models are employed and compared. Mean and fluctuating fields obtained by three-dimensional computational fluid dynamics modeling are compared to experimental data. Turbulence statistics such as integral length scale, Taylor microscale, Kolmogorov scale, turbulence kinetic energy, dissipation rate, and velocity correlations are calculated at different experimental conditions (i.e., pressure, temperature, fan speed, etc.). A reasonably isotropic and homogeneous turbulence with large turbulence intensities is achieved in the central region extending to almost 45 mm radius. This radius decreases with increasing the initial pressure. The influence of the third dimension velocity component on the measured characteristics is negligible. This is a result of the axisymmetric features of the flow pattern in the current vessel. The results prove that the present vessel can be conveniently adopted for several turbulent combustion studies including mainly the determination of turbulent burning velocity for gaseous premixed flames in nearly homogeneous isotropic turbulence.

Graphic abstract

中文翻译：

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大型风扇搅拌燃烧容器湍流统计数值及实验研究

摘要

粒子图像测速 (PIV) 已成为一种流行的非侵入式工具，用于测量各种类型的流量。然而，当使用二维 (2D) PIV 测量三维流动时，由于平面外运动，测量的速度场存在一些不确定性，这可能会改变湍流统计并扭曲整体流动特性。在本研究中，采用并比较了三种不同的湍流模型。通过三维计算流体动力学建模获得的平均场和波动场与实验数据进行了比较。在不同的实验条件（即压力、温度、风扇速度等）下计算湍流统计量，例如积分长度尺度、泰勒微尺度、Kolmogorov 尺度、湍流动能、耗散率和速度相关性。在延伸到几乎 45 毫米半径的中心区域实现了具有大湍流强度的合理各向同性和均匀的湍流。该半径随着初始压力的增加而减小。三维速度分量对测量特性的影响可以忽略不计。这是当前容器中流动模式的轴对称特征的结果。结果证明，本容器可方便地用于多种湍流燃烧研究，主要包括测定近均匀各向同性湍流中气体预混火焰的湍流燃烧速度。三维速度分量对测量特性的影响可以忽略不计。这是当前容器中流动模式的轴对称特征的结果。结果证明，本容器可方便地用于多种湍流燃烧研究，主要包括测定近均匀各向同性湍流中气体预混火焰的湍流燃烧速度。三维速度分量对测量特性的影响可以忽略不计。这是当前容器中流动模式的轴对称特征的结果。结果证明，本容器可方便地用于多种湍流燃烧研究，主要包括测定近均匀各向同性湍流中气体预混火焰的湍流燃烧速度。

图形摘要