An application of tomographic PIV to investigate the spray-induced turbulence in a direct-injection engine
An application of tomographic PIV to investigate the spray-induced turbulence in a direct-injection engine
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DOI：
10.1016/j.ijmultiphaseflow.2019.103116
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发表时间：
2019-12-01
影响因子：
3.8
通讯作者：
Peterson, B.
中科院分区：
文献类型：
--
作者：
Hill, H.;Ding, C. -P.;Peterson, B.
燃料喷雾产生高速、喷射状的流，其将湍流施加到环境流场上。这种喷雾诱导的湍流增强了燃料-空气的快速混合，这在控制直喷式发动机中的污染物形成和循环可变性方面具有主要作用。本文介绍了层析粒子图像测速（TPIV）测量分析的三维喷雾诱导湍流在进气冲程的直喷火花点火（DISI）发动机。喷雾在远场产生强烈的喷雾诱导射流（SIJ），其穿过圆柱体并将湍流施加到周围的流上。在4.8 kHz的平面高速PIV测量与TPIV在3.3 Hz相结合，以评估喷雾颗粒分布和验证TPIV测量的颗粒负载流。进行全面的不确定性分析，以评估与单个涡量和应变率组件相关的不确定性。TPIV分析量化了与SIJ相关的湍流空间域，并描述了湍流动能（TKE）、应变率（S）和涡量（Omega）等湍流特征如何演变为周围流场。获得完整的S和Omega张量有助于评估单个喷雾事件的湍流。TPIV图像显示存在强剪切层（可视化的高S级）和口袋的升高涡沿着的SIJ的直接边界。S和Ω值从SIJ以1 mm增量延伸的空间域中提取。湍流水平在距SIJ边界0-1 mm区域内最大，并随径向距离消散。个别应变率和涡度分量进行了详细分析，以描述局部应变率和三维涡结构内产生的强剪切层的SIJ之间的关系。分析的目的是了解负责快速燃料-空气混合的流动特征，并为数值模型的开发提供有价值的数据。(C)2019爱思唯尔有限公司版权所有。
Fuel sprays produce high-velocity, jet-like flows that impart turbulence onto the ambient flow field. This spray-induced turbulence augments rapid fuel-air mixing, which has a primary role in controlling pollutant formation and cyclic variability in direct-injection engines. This paper presents tomographic particle image velocimetry (TPIV) measurements to analyze the 3D spray-induced turbulence during the intake stroke of a direct-injection spark-ignition (DISI) engine. The spray produces a strong spray-induced jet (SIJ) in the far field, which travels through the cylinder and imparts turbulence onto the surrounding flow. Planar high-speed PIV measurements at 4.8 kHz are combined with TPIV at 3.3 Hz to evaluate spray particle distributions and validate TPIV measurements in the particle laden flow. A comprehensive uncertainty analysis is performed to assess the uncertainty associated with individual vorticity and strain rate components.TPIV analyses quantify the spatial domain of the turbulence in relation to the SIJ and describe how turbulent flow features such as turbulent kinetic energy (TKE), strain rate (S) and vorticity (Omega) evolve into the surrounding flow field. Access to the full S and Omega tensors facilitate the evaluation of turbulence for individual spray events. TPIV images reveal the presence of strong shear layers (visualized by high S magnitudes) and pockets of elevated vorticity along the immediate boundary of the SIJ. S and Omega values are extracted from spatial domains extending in 1 mm increments from the SIJ. Turbulence levels are greatest within the 0-1 mm region from the SIJ boarder and dissipate with radial distance. Individual strain rate and vorticity components are analyzed in detail to describe the relationship between local strain rates and 3D vortical structures produced within strong shear layers of the SIJ. Analyses are intended to understand the flow features responsible for rapid fuel-air mixing and provide valuable data for the development of numerical models. (C) 2019 Elsevier Ltd. All rights reserved.