中等雷诺数二维平面扩散器的非定常RANS性能分析

IF 2 3区 工程技术 Q3 MECHANICS
Alex Ravaioli, Rithvik Magal, Alessandro Talamelli, Gabriele Bellani
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引用次数: 0

摘要

扩散器是在许多工程应用中发现的装置,其性能和设计是许多研究的对象。然而,相对较少的研究致力于在低和中等雷诺数下工作的扩散器。在这种情况下,流动可以是层流、湍流或过渡流,扩压器的气动性能高度依赖于雷诺数的具体值和进口条件。特别是,目前的研究侧重于评估进口条件对特定雷诺数下二维扩散器的性能和流动行为的作用(\(Re \approx 8000\))。此外,扩散器在固定腔室中放电,并且不呈现尾管结构,这一条件迄今为止在现有文献中尚未发现明确的存在。在\(Re = 8163\)对二维平面扩散器进行了9种不同情况下的数值研究,包括不同的进口湍流强度(0.05、3和10%)和不同堵塞系数(0、0.05和0.33)下的速度分布。对于每种情况,辐散角范围为0 ~ 30度,并使用\(k-\omega\)过渡海温模式进行了多次URANS模拟,该模式考虑了边界层可能的过渡。结果表明,对于具有薄边界层的高雷诺数扩散器的设计建议并不总是适用,并且在处理不能确保入口足够高湍流水平的操作条件时必须非常谨慎。失速状态的发散角被显示,性能指标(例如压力恢复系数)被报告。这些结果表明,当湍流强度从10%降低到0.05%时,压力恢复有很大的下降(高达60%)。速度剖面的堵塞系数对性能也有重要影响。为了简化不同堵塞因素之间的比较,采用改进的有效性来解释非均匀进口速度曲线所带来的畸变。
本文章由计算机程序翻译,如有差异,请以英文原文为准。

Performance Analysis of Two-Dimensional Plane Diffusers at a Moderate Reynolds Number by Means of Unsteady RANS

Performance Analysis of Two-Dimensional Plane Diffusers at a Moderate Reynolds Number by Means of Unsteady RANS

Diffusers are devices found in several engineering applications and their performance and design are object of numerous investigations. However, relatively few investigations have been dedicated to diffusers operating at low and moderate Reynolds numbers. In this regime, the flow could be laminar, turbulent or transitional, and the aerodynamic performance of the diffuser becomes highly dependent on the specific value of the Reynolds number and inlet conditions. In particular, the present study focuses on evaluating the role of inlet conditions on the performance and flow behaviour of two-dimensional diffusers on this specific Reynolds number regime (\(Re \approx 8000\)). Furthermore, the diffuser discharges in a stationary chamber and it does not present a tail-pipe configuration, a condition that has not found a clear presence in the existing literature so far. A numerical investigation of two-dimensional plane diffusers was performed at \(Re = 8163\) for 9 different cases, combined varying the inlet turbulence intensity (0.05, 3, and 10 percent), and the velocity profile, characterised by different blockage factors (0, 0.05 and 0.33). For each case, the divergence angle ranged from 0 to 30 degrees, and several URANS simulations were performed using the \(k-\omega\) Transitional SST model that accounts for the possible transition of the boundary layer. The results show that the design recommendations valid for high Reynolds number diffusers with a thin boundary layer are not always applicable, and extreme caution must be exercised when dealing with operating conditions that do not ensure a sufficiently high turbulence level at the inlet. The divergence angles of the stall regimes are shown, and performance indicators (e.g. pressure-recovery coefficients) are reported. These reveal a strong decrement (up to 60 percent) of the pressure recovery on reducing turbulence intensity from 10 percent to 0.05 percent. The blockage factor of the velocity profile has an important effect on performance as well. In order to simplify the comparison between the different blockage factors, a modified effectiveness was employed to account for the distortion introduced by a non-uniform inlet velocity profile.

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来源期刊
Flow, Turbulence and Combustion
Flow, Turbulence and Combustion 工程技术-力学
CiteScore
5.70
自引率
8.30%
发文量
72
审稿时长
2 months
期刊介绍: Flow, Turbulence and Combustion provides a global forum for the publication of original and innovative research results that contribute to the solution of fundamental and applied problems encountered in single-phase, multi-phase and reacting flows, in both idealized and real systems. The scope of coverage encompasses topics in fluid dynamics, scalar transport, multi-physics interactions and flow control. From time to time the journal publishes Special or Theme Issues featuring invited articles. Contributions may report research that falls within the broad spectrum of analytical, computational and experimental methods. This includes research conducted in academia, industry and a variety of environmental and geophysical sectors. Turbulence, transition and associated phenomena are expected to play a significant role in the majority of studies reported, although non-turbulent flows, typical of those in micro-devices, would be regarded as falling within the scope covered. The emphasis is on originality, timeliness, quality and thematic fit, as exemplified by the title of the journal and the qualifications described above. Relevance to real-world problems and industrial applications are regarded as strengths.
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