Heat and mass transfer on blunt nose sections of high-speed aircraft under aerodynamic heating

Аuthors

Tushavina O. V.

Moscow Aviation Institute (National Research University), 4, Volokolamskoe shosse, Moscow, А-80, GSP-3, 125993, Russia

e-mail: tushavinaov@mai.ru

Abstract

This study presents an approximate analytical model for analyzing thermal loads on blunt nose sections of high-speed aircraft (HSA) under aerodynamic heating conditions. By solving the system of equations for a dissociating boundary layer in Dorodnitsyn-Les variables, closed-form expressions were derived to determine convective and diffusive heat fluxes at the forward stagnation point. The balance equations, integrating convective-conductive, diffusive, and radiative heat fluxes, were employed to calculate the surface temperature of the blunt body, ensuring a comprehensive account of mutual interactions between different heat transfer mechanisms under high-speed gas flow and chemical dissociation. Numerical simulations were conducted across a wide range of Mach numbers (M), atomic species concentrations in binary gas mixtures, and catalytic recombination coefficients, establishing quantitative relationships between these parameters and surface thermal characteristics. The results highlight the substantial impact of material catalytic activity on heat flux distribution: an increase in the recombination coefficient amplifies the diffusive heat transfer component, which, combined with convective heating, significantly elevates surface temperatures. Analysis of threshold values for key parameters (M, concentration, catalytic efficiency) identified critical conditions leading to temperatures that trigger mass ablation of thermal protection materials, enabling the formulation of guidelines for material selection and thermal management system design.
The research underscores the necessity of integrated consideration of both gasdynamic and chemical-kinetic factors when predicting HSA thermal regimes, particularly at hypersonic speeds where gas dissociation and catalytic effects dominate. The derived closed-form expressions and numerical correlations can optimize thermal protection coatings, reduce structural mass, and enhance vehicle reliability under extreme thermal environments. This work contributes to advancing thermal load prediction methodologies by offering an analytical tool for rapid assessment of critical parameters without resource-intensive CFD simulations. Furthermore, the study provides a framework for determining operational limits of thermal protection materials by correlating surface temperature thresholds with flight envelope constraints. The obtained dependencies reveal nonlinear interactions between Mach number and catalytic activity: at lower M, radiative cooling partially mitigates convective heating, while at higher M, dissociation-driven diffusion fluxes become predominant. Parametric studies demonstrate that maintaining surface temperatures below ablation thresholds requires a trade-off between catalytic efficiency (to reduce atomic species concentration) and material emissivity (to enhance radiative cooling). The proposed model bridges the gap between simplified engineering methods and high-fidelity simulations, offering a balance between accuracy and computational efficiency for preliminary design stages. By polynizing parameter variation limits, the research establishes safety margins for HSA thermal protection systems, ensuring compliance with mass loss constraints under transient heating scenarios.

Keywords:

heat and mass transfer, high-speed aircraft, aerodynamic heating, convective heat fluxes, diffusive heat fluxes, catalytic recombination, Mach numbers, thermal protection materials, critical point, Dorodnitsyn-Lize equations

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