Characterization of Structural Response to Hypersonic Boundary-Layer Transition

Abstract

The inherent relationship between boundary-layer stability, aerodynamic heating, and surface conditions makes the potential for interaction between the structural response and boundary-layer transition an important and challenging area of study in high-speed flows. This paper phenomenologically explores this interaction using a fundamental two-dimensional aerothermoelastic model under the assumption of an aluminum panel with simple supports. Specifically, an existing model is extended to examine the impact of transition onset location, transition length, and transitional overshoot in heat flux and fluctuating pressure on the structural response of surface panels. Transitional flow conditions are found to yield significantly increased thermal gradients, and they can result in higher maximum panel temperatures compared to turbulent flow. Results indicate that overshoot in heat flux and fluctuating pressure reduces the flutter onset time and increases the strain energy accumulated in the panel. Furthermore, overshoot occurring near the midchord can yield average temperatures and peak displacements exceeding those experienced by the panel subject to turbulent flow. These results suggest that fully turbulent flow does not always conservatively predict the thermo-structural response of surface panels. Nomenclature b = compressibility exponent c = specific heat capacity c f = skin-friction coefficient E = modulus of elasticity F c = compressible flow transformation function h = panel thickness k = thermal conductivity L = panel length p = unsteady aerodynamic pressurẽ p = root-mean-square fluctuating pressure Q = aerodynamic heat flux q = dynamic pressure Re θ = momentum thickness Reynolds number T = temperature t = time t F = panel flutter onset time u = fluid velocity w = transverse panel displacement x = chordwise spatial coordinate x t = transition onset location x te = end of transition region x = spatial location nondimensionalized by panel length z = through-thickness spatial coordinate α = thermal expansion coefficient β = standard deviation γ = intermittency Δx t = transition length (x te − x t ) δ 1 = boundary-layer displacement thickness Θ = overall phase angle λ = viscosity/velocity power law exponent ν = Poisson's ratio ρ = panel density σ = spot propagation parameter τ = temporal phase angle ϕ = power spectral density ψ = spatial phase angle ω = angular frequency Subscripts avg = average e = boundary-layer edge lam = laminar max = maximum tran = transitional turb = turbulent VO = virtual origin

Thermomechanical response of metal-ceramic graded composites for high-temperature aerospace applications

“…Such an assumption leads to aerodynamic heating of approximately four to eight times that of laminar flow [117]. Modeling of the correct transitional boundary layers has been found to produce significantly higher thermal gradients, which can result in higher panel temperatures than that of purely turbulent flows [118]. Therefore, working with members of the AFRL Munitions Directorate, the location of the transitional boundary layer has been approximated, and models of the location have been created to determine the influence of non-uniform heating conditions on the thermal and thermostructural response.…”

“…For this study, the same representative time-dependent structural and thermal loads used in the uniform heat flux example are utilized and modified to model the [118], where the laminar to turbulent heat flux transition is a continuous…”

Broadband Design of Acoustic Metasurfaces for the Stabilization of a Mach 4 Boundary Layer Flow

“…2 Department of Aeronautical and Aviation Engineering, The Hong Kong Polytechnic University, Kowloon, Hong Kong, China. 3 State Key Laboratory of High Temperature Gas Dynamics, Institute of Mechanics, Chinese Academy of Science, Beijing 100190, China.…”

“…High-speed boundary layer (BL) transition is one of the crucial issues for the design of supersonic transports and reentry vehicles. Compared to laminar flow, early transition generates a significant increase in viscous drag and heat flux, which leads to high requirements for thermal protection system (TPS) [1][2][3]. For high-attitude flights in a low disturbance environment and with negligible surface roughness, it is acknowledged that the transition is due to amplification of unstable modes in the BL [4].…”

Broadband design of acoustic metasurfaces for the stabilization of a Mach 4 boundary layer flow

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High-speed boundary layer (BL) transition is one of the crucial issues for the design of supersonic transports and reentry vehicles. Compared to laminar flow, early transition generates a significant increase in viscous drag and heat flux, which leads to high requirements for thermal protection system (TPS) [1][2][3]. For high-attitude flights in a low disturbance environment and with negligible surface roughness, it is acknowledged that the transition is due to amplification of unstable modes in the BL [4].

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