Purpose

The transpiration has been recognized as one of the most effective thermal protection methods for future hypersonic vehicles. To improve efficiency and safety, it is urgent to optimize the design of the transpiration system for heat and drag reduction. The purpose of this paper is to investigate the effects of transpiration on heat and drag reduction.

Design/methodology/approach

A chemical nonequilibrium flow model with the transpiration is established by using Navier–Stokes equations, the shear-stress transport turbulence model, thermodynamic properties and the Gupta chemical kinetics model. The solver programmed for this model is verified by comparing with experimental results in the literature. Effects of air injection on the flow field, the aerodynamic resistance and the surface heat flux are calculated with the hypersonic flow past a blunt body. Furthermore, a modified blocking coefficient formula is proposed.

Findings

Numerical results show that the transpiration can reduce the aerodynamic resistance and the surface heat flux observably and increase the shock wave standoff distance slightly. It is also manifested that the modified formula is in better agreement with the wind tunnel test results than the original formula.

Originality/value

The modified formula can expand the application range of the engineering method for the blocking coefficient. This study will be beneficial to carry out the optimal design of the transpiration system.

中文翻译：

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高超声速流蒸腾减热减阻的数值研究

目的

蒸腾被认为是未来高超音速飞行器最有效的热防护方法之一。为了提高效率和安全性，迫切需要优化蒸腾系统的减热减阻设计。本文的目的是研究蒸腾作用对减热减阻的影响。

设计/方法论/途径

利用Navier-Stokes方程、剪应力输运湍流模型、热力学性质和Gupta化学动力学模型建立了含蒸腾作用的化学非平衡流动模型。通过与文献中的实验结果进行比较，验证了针对该模型编写的求解器。以流经钝体的高超声速流为例，计算了空气喷射对流场、气动阻力和表面热通量的影响。此外，还提出了一种改进的阻塞系数公式。

发现

数值结果表明，蒸腾作用可显着降低气动阻力和表面热通量，并略微增加激波间隔距离。还表明，修正后的公式比原公式与风洞试验结果更加吻合。

原创性/价值

修改后的公式可以扩大分块系数工程方法的应用范围。本研究将有利于蒸腾系统的优化设计。