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

Abstract

The invention relates to the technical field of aerodynamic thermal solution of an aircraft flow field, and discloses a high-precision heat flow calculation method based on an unstructured grid regularization reconstruction technology. This method starts from the idea of ​​using the initial flow field to extract the characteristic surface, combined with the shock wave detection technology and the three-dimensional shock wave surface fitting technology, multiple iterations are gradually approached to find the spatial shock wave surface that conforms to the real physical understanding, and the heat flow network at the stagnation point of the object surface The grid is regularized and the grid near the space shock surface is reconstructed twice, so as to eliminate the numerical error caused by the random arrangement and disturbance of the grid. Under the premise of ensuring the rapid generation of the overall unstructured grid, the method proposed by the present invention uses semi-automatic grid repair technology to iteratively reconstruct and form a regularized grid that conforms to physical characteristics, and eliminates numerical calculation errors caused by grid disturbances , providing a new fast and detailed simulation method for hypersonic vehicle aerothermal simulation.

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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