High-precision heat flow calculation method based on unstructured grid regularization reconstruction technology

Abstract

The invention relates to the technical field of aircraft flow field aerodynamic heat solution, and discloses a high-precision heat flow calculation method based on an unstructured grid regularization reconstruction technology. According to the method, starting from the idea that an initial flow field is used for feature surface extraction, the shock wave detection technology and the three-dimensional shock wave curved surface fitting technology are combined, a space shock wave surface meeting the real physical understanding is found through multiple times of iteration step by step, regularization processing is conducted on an object surface stationary point heat flow grid, and secondary skin reconstruction is conducted on grids near the space shock wave surface, therefore, numerical errors caused by random arrangement and disturbance of the grids are eliminated. According to the method provided by the invention, on the premise of ensuring rapid generation of the overall unstructured grid, the regularized grid conforming to the physical characteristics is formed through repeated iterative reconstruction by using a semi-automatic grid repair technology, so that numerical calculation errors caused by grid disturbance are eliminated, and a new rapid and fine simulation method is provided for aerodynamic heat simulation of the hypersonic aircraft.

Description

technical field [0001] The invention relates to the technical field of aerothermal solution of aircraft flow field, in particular to a high-precision solution method for heat flow near a stagnation point of a hypersonic aircraft. Background technique [0002] Accurately predicting the aerodynamic thermal environment is the core technology of thermal protection design for hypersonic vehicles. The currently commonly used method is to discretely solve the N-S equation based on computational fluid dynamics (CFD) technology to obtain spatial flow field information, and further obtain the aerodynamic and thermal characteristic parameters of the aircraft by analyzing the flow field information. The current CFD calculation methods mainly include two categories based on structured grids and unstructured grids. Since the heat flow calculation requires accurate prediction of the aircraft surface temperature gradient, the method based on structured grids is due to the regularization of ...

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Problems solved by technology

The current CFD calculation methods mainly include two categories based on structured grids and unstructured grids. Since the heat flow calculation requires accurate prediction of the aircraft surface temperature gradient, the method based on structured grids is due to the regularization of grids. Better layout characteristics can usually obtain higher-precision simulation results, but a significant problem with structured grids is that grid generation takes too long, and topology design is difficult in local areas with complex shapes, which affects the heat flow of complex shapes. Calculation has brought great challenges; unstructured grids have the advantages of automation, flexibility and high efficiency, and can better solve the problem of grid generation efficiency for complex aircraft shapes. Therefore, the CFD technology based on unstructured grids It has received more and more attention in the field of numerical simulation calculation of aerodynamic heat

However, the application of unstructured grids still has the following problems: (1) due to the irregular arrangement of unstructured grids, the prediction accuracy of heat flow will be insufficient; (2) when the spatial grids are not arranged strictly along the shock wave, the shock wave There will be a large disturbance error in the flow field behind the wave, and this disturbance error will propagate to the vicinity of the stagnation point. In extreme cases, the error may dominate the flow field, causing the shock wave to protrude outward, forming the so-called "red jade" phenomenon , leading to non-physical flow field solutions, etc.

Although the method based on unstructured grid self-adaptation can automatically encrypt the grid near the shock wave and make the shock wave simulation more precise, it still cannot realize the strict arrangement of the grid along the shock wave, and cannot eliminate the problem caused by the grid. disturbance error

Similarly, although the shock wave assembly method can realize the grid arrangement strictly along the shock wave, the calculation is complicated and the stability is poor.

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