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首页> 外文期刊>The Aeronautical Journal >A turbulence model study of separated 3D jet/afterbody flow
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A turbulence model study of separated 3D jet/afterbody flow

机译：分离的3D射流/尾流的湍流模型研究

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Three-dimensional RANS calculations and comparisons with experimental data are presented for subsonic and transonic flow past a non-axisymmetric (rectangular) nozzle/afterbody typical of those found in fast-jet aircraft. The full details of the geometry have been modelled, and the flow domain includes the internal nozzle flow and the jet exhaust plume. The calculations relate to two free-stream Mach numbers of 0.6 and 0.94 and have been performed during the course of a collaborative research programme involving a number of UK universities and industrial organisations. The close interaction between partners contributed greatly to the elimination of computational inconsistencies and to rational decisions on common grids and boundary conditions, based on a range of preliminary computations. The turbulence models used in the study include linear and nonlinear eddy-viscosity models. For the lower Mach number case, the flow remains attached and all of the turbulence models yield satisfactory pressure predictions. However, for the higher Mach number, the flow over the afterbody is massively separated, and the effect of turbulence model performance is pronounced. It is observed that non-linear eddy-viscosity modelling provides improved shock capturing and demonstrates significant turbulence anisotropy. Among the linear eddy-viscosity models, the SST model predicts the best surface pressure distributions. The standard k - ε model gives reasonable results, but returns a shock location which is too far downstream and displays a delayed recovery. The flow field inside the jet nozzle is not influenced by turbulence modelling, highlighting the essentially inviscid nature of the flow in this region. However, the resolution of internal shock cells for identical grids is found to be dependent on the solution algorithm - specifically, whether it solves for pressure or density as a main dependent variable. Density-based time-marching schemes are found to return a better resolution of shock reflection. The paper also highlights the urgent need for more detailed experimental data in this type of flow.
机译：对于通过非轴对称（矩形）喷嘴/后喷嘴的亚音速和跨音速流动，进行了三维RANS计算并与实验数据进行了比较，这在快速喷气飞机中是典型的。已对几何图形的所有细节进行了建模，并且流域包括内部喷嘴流和喷射尾流。这些计算与两个自由流马赫数分别为0.6和0.94有关，并且是在涉及英国许多大学和工业组织的一项合作研究计划的过程中进行的。伙伴之间的密切互动极大地消除了计算上的矛盾，并基于一系列初步计算为共同网格和边界条件做出了合理的决策。在研究中使用的湍流模型包括线性和非线性涡粘性模型。对于较低马赫数的情况，流动保持附着，并且所有的湍流模型都能产生令人满意的压力预测。但是，对于更高的马赫数，在车身后部的流动被大量分离，湍流模型性能的影响非常明显。可以观察到，非线性涡流-粘度建模提供了改进的震动捕捉，并显示出显着的湍流各向异性。在线性涡流-粘度模型中，SST模型可预测最佳的表面压力分布。标准的k-ε模型给出了合理的结果，但返回的冲击位置距离下游太远，恢​​复延迟。射流喷嘴内的流场不受湍流建模的影响，突出了该区域内流的本质是无粘性的。但是，发现内部冲击单元对于相同网格的分辨率取决于求解算法-具体地说，是求解压力还是密度作为主要因变量。发现基于密度的时间前进方案可以返回更好的冲击反射分辨率。本文还强调了此类流中迫切需要更详细的实验数据。

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