Purpose

The design of a space launcher requires some considerations about the unsteady loads and heat transfer occurring at the base of the structure. In particular, these phenomena are predominant during the early stage of the flight. This paper aims to evaluate the ability of the unstructured, high order finite-volume CFD solver FLUSEPA, developed by Airbus Safran Launchers, to accurately describe these phenomena.

Design/methodology/approach

This paper first performs a steady simulation on a base flow around a four-clustered rocket configuration. Results are compared with NASA experiments and Loci-CHEM simulations. Then, unsteady simulations of supersonic H2/air reacting mixing layer based on the experiment of Miller, Bowman and Mungal are performed. Three meshes with different cells number are used to study the impact of spatial resolution. Instantaneous and time-averaged concentrations are compared with the combined OH/acetone planar laser-induced fluorescence imaging from the experiment.

Findings

FLUSEPA satisfactorily predicts the base heat flux at the base of a four-clustered rocket configuration. NASA Loci-CHEM reactive simulations indicate that afterburning plays an important role and should not be neglected. The unsteady reactive computation of a supersonic mixing layer shows that FLUSEPA is also able to accurately predict flow structures and interactions. However, the complexity of the experiment and the lack of details concerning the facility prevents from obtaining satisfactory converged results.

Originality/value

This study is the first step on the development of a cost-effective method aiming at predicting unsteady loads and heat transfer on space launchers using an unsteady and reactive model for the CDF calculations. It uses original techniques such as conservative CHIMERA-like overset grids, local re-centering of fluxes and local adaptive time-stepping to reduce computational cost while being robust and accurate.

中文翻译：

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空间发射器应用中反应性超音速/亚音速流动相互作用的模拟

目的

空间发射器的设计需要考虑结构底部发生的不稳定载荷和热传递。特别是，这些现象在飞行的早期阶段占主导地位。本文旨在评估由 Airbus Safran Launchers 开发的非结构化高阶有限体积 CFD 求解器 FLUSEPA 准确描述这些现象的能力。

设计/方法/方法

本文首先对围绕四组火箭配置的基流进行了稳定模拟。结果与 NASA 实验和 Loci-CHEM 模拟进行了比较。然后，基于Miller、Bowman 和Mungal 的实验对超音速H2 /空气反应混合层进行了非定常模拟。使用具有不同单元数的三个网格来研究空间分辨率的影响。将瞬时和时间平均浓度与来自实验的组合 OH/丙酮平面激光诱导荧光成像进行比较。

发现

FLUSEPA 令人满意地预测了四组火箭配置底部的基础热通量。NASA Loci-CHEM 反应模拟表明，加力燃烧起着重要作用，不容忽视。超音速混合层的非稳态反应计算表明，FLUSEPA 还能够准确预测流动结构和相互作用。然而，实验的复杂性和缺乏有关设施的细节阻碍了获得令人满意的收敛结果。

原创性/价值

这项研究是开发具有成本效益的方法的第一步，该方法旨在使用非稳态和反应模型进行 CDF 计算来预测空间发射器的非稳态载荷和热传递。它使用原始技术，例如保守的类似 CHIMERA 的重叠网格、通量的局部重新定心和局部自适应时间步长，以降低计算成本，同时具有鲁棒性和准确性。