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Open Access Issue
Efficient prediction method for aerodynamic heating in hypersonic cone boundary-layer transition
Journal of National University of Defense Technology 2026, 48(1): 217-226
Published: 01 February 2026
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Objective

The objective is to develop a reliable prediction method to reduce the redundancy in thermal protection system design, thereby decreasing the cost and weight of hypersonic vehicles while enhancing their design efficiency and performance. existing prediction techniques such as engineering algorithms, wind - tunnel tests, and numerical calculations have limitations. hence, this research aims to establish a more effective prediction model.

Methods

The methods employed were as follows: First, a VAE(variational autoencoder) - based generative prediction framework was established. Principal component analysis was used to determine the optimal dimension of the latent variable space of the VAE model, which was set to 16. The VAE model, with a structure based on a convolutional neural network and including a residual convolutional encoder and decoder, was trained to extract low - dimensional latent space representations of complex heat flux fields. A fully - connected neural network was then constructed to establish the nonlinear mapping between free - stream parameters and latent variables. The two models were cascaded to form a hypersonic cone transition heat flux prediction model. Additionally, computational fluid dynamics using the Fluent software were carried out on a conical model with specific geometric parameters and flow conditions to generate the training and validation datasets.

Results

The results show that the VAE model can effectively extract heat flux field latent variables and accurately reconstruct the heat flux field structure of the leeward - side streamwise vortex transition. The prediction model can efficiently learn the heat flux distribution characteristics under complex transition mechanisms. The average reconstruction error of the VAE model on the training set is less than 0.03, and on the validation set is less than 0.028. The prediction error of the integrated model for heat flux under different free - stream conditions is not higher than 0.024, indicating high - precision prediction capabilities.

Conclusions

In conclusion, this study successfully combines generative deep - learning methods with a transition heat flux database from numerical simulations. The established artificial intelligence model can accurately and efficiently reconstruct and predict the three - dimensional boundary - layer transition heat flux field of hypersonic cones under different free - stream conditions. The VAE model demonstrates excellent feature extraction and reconstruction abilities, and the fully - connected neural network effectively maps free - stream parameters to latent variables. This research provides a new approach for hypersonic aerodynamic heating prediction, which has important implications for the design and development of hypersonic vehicles.

Open Access Issue
Skin friction measurement and drag reduction of porous media under cryogenic and high Reynolds number conditions
Acta Aerodynamica Sinica 2024, 42(8): 84-92
Published: 18 July 2024
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To investigate the drag reduction laws and the Reynolds number effects of porous media under cryogenic and high Reynolds number conditions, this study conducted skin-friction measurements and drag reduction experiments in a 0.3 m transonic cryogenic wind tunnel. Pressure sensors and oil flow devices were installed downstream of the smooth plate and porous media region respectively, to measure the power spectra of fluctuating pressure and the global skin friction. It is shown that the skin friction coefficient decreases with the increase of Reynolds number. With the increase of Reynolds number (increasing the Mach number or decreasing the total temperature of the incoming flow), the porous media drag reduction ratio shows a non-uniform decreasing trend. Besides, the introduction of porous media, the low-frequency signal strength of the downstream pulsating pressure increases, and the intensity of the high-frequency signal is weakened. Under the typical condition that Mach number Ma = 0.300, Reynolds number Re = 7.51×106 and the total temperature of the incoming flow T0 = 140 K, the drag reduction ratio of porous media is 11.4%, which initially verifies the feasibility of the drag reduction control strategy under low temperature and high Reynolds number conditions.

Open Access Research Article Issue
Numerical and experimental study on opposing jet in hypersonic flow
Acta Aerodynamica Sinica 2022, 40(4): 101-109
Published: 20 December 2021
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As an active flow control technology, the opposing jet has become a research hotspot due to its broad prospect in reducing aerodynamic heat. In order to explore the heat flux reduction law and related mechanism of opposing jet flow control for hypersonic vehicles, a hemispherical bluff body model was studied by numerical simulations and wind tunnel experiments under different freestream and opposing jet conditions. The flow field and Stanton number distribution on the model surface were obtained, and both numerical and experimental data were verified against each other. The results suggest that, the heat flux reduction effect of the opposing jet is the consequence of a combined action of the jet backflow and the jet pushing away the front shockwave from the head. At a fixed Mach number, the heat flux reduction effect of opposing jet becomes more obvious with the increase of the jet pressure ratio; while under the condition of a similar jet pressure ratio, better heat flux reduction effect by the opposing jet can be achieved at higher Mach numbers.

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