Hypersonic Computational Fluid Dynamics Heat Flux Sub-Models Development

OUSD (R&E) CRITICAL TECHNOLOGY AREA(S): Hypersonics OBJECTIVE: Enhance Modeling and Simulation (M&S) of Navy-relevant hypersonic flows through the development and/or improvement of Computational Fluid Dynamics (CFD) turbulence-heat flux sub-models. DESCRIPTION: At present, CFD prediction of heat flux in hypersonic flows relies on simplified approximation of the relationship between fluid transport, turbulence, and heat flux. These models are not rooted in fundamental physics and are typically tuned to yield reasonable agreement with a select number of canonical sub- and transonic flows. Consequently, existing turbulence models can produce larger errors when attempting to predict heat flux for hypersonic flows. The objective of this topic is to enhance M&S of Navy-relevant hypersonic flows through the development and/or improvement of CFD turbulence-heat flux sub-models. Proposers should define a framework for heat flux modeling of the Favre-averaged, reacting Navier-Stokes equations, develop a heat flux sub-model that can be easily integrated into existing RANS-based CFD solvers, and demonstrate the predictive capability of the model through verification and validation (V&V) against existing hypersonics datasets. PHASE I: Develop and present a turbulence modeling framework based on the Favre-averaged, reacting Navier-Stokes equations. Provide a heat flux sub-model for hypersonic, turbulent flows that shows improvements in physical realism, predictive capability, and numerical performance/robustness over existing heat flux sub-models. Ideally, the model should be generalizable across flight conditions (i.e., subsonic to hypersonic). The functional form of the heat flux sub-model must be capable of seamless integration into existing compressible RANS and hybrid RANS/LES turbulence modeling frameworks, i.e., the model should take as inputs only those variables used/stored by industry-standard RANS/LES algorithms and their sub-models, be continuous in form, rely only on local data, and should ideally be turbulence model agnostic. The Phase I effort will include prototype plans to be developed under Phase II. PHASE II: Refine the form of the model(s) and define any constants needed to close the model. Constants and model specifics should be driven by a combination of first principles and existing experimental/flight test data. Collaborate with the High Performance Computing Modernization Program (HPCMP) CREATE Air Vehicle (CREATE-AV) development team to incorporate the model(s) into a CFD architecture, verify the model implementation, and validate the model against existing hypersonics databases using best V&V practices. Further refine the model form, constants, and implementation based on V&V activities. Finalize the heat flux sub-model by demonstrating model integration into an existing turbulence modeling framework plus improvements in predictive capability for Navy-relevant hypersonic flows, and transitioning the model to CREATE tools. PHASE III DUAL USE APPLICATIONS: Transition the finalized model(s) along with all supporting documentation, rationale, and source code to the HPCMP CREATE development team for (1) implementation into its Kestrel CFD solver, (2) standard verification testing, and comparison to/validation against existing databases,. Complete any necessary alterations to the model or its source code requested by the HPCMP CREATE team. Improved heat flux modeling will benefit commercial computational fluid dynamics solvers and commercial entities that utilize CFD for design and analysis. In addition to hypersonic systems, improved heat flux modeling will benefit commercial sectors producing turbomachinery, internal combustion engines, and other problems where heat transfer due to fluid-solid-interaction plays an important role in design, performance, and sustainment. REFERENCES: 1. Marvin, J.G. and Coakley, T.J, "Turbulence Modeling for Hypersonic Flows." NASA Technical Report, NASA-TM-101079, NASA Ames Research Center, June 1989. https://ntrs.nasa.gov/api/citations/19890016810/downloads/19890016810.pdf 2. Danis, M.E. and Durbin, P. "Compressibility Correction to k-w Models for Hypersonic Turbulent Boundary Layers." AIAA Journal, Vol. 60, No, 11, November 2022. DOI: 10.2514/1.J06027 https://arc.aiaa.org/doi/10.2514/1.J062027 3. Bowersox, R.D.W. and North, S.W. "Algebraic turbulent energy flux models for hypersonic shear flows." Progress in Aerospace Sciences, vol. 46, issue 2-3, February-April 2010, pp. 49-61. DOI: 10.1016/j.paerosci.2009.11.006 4. Huang, J.; Nicholson, G.L.; Duan, L.; Choudhari, M.M. and Bowersox, R.D.W. "Simulation and Modeling of Cold-Wall Hypersonic Turbulent Boundary Layers on a Flat Plate." AIAA Science and Technology Forum, 06-10 Jan 2020, Orlando, FL, USA, AIAA 2020-0571. DOI: 10.2514/6.2020-0571 KEYWORDS: Hypersonic; Turbulence Modeling; Heat Flux; Computational Fluid Dynamics; CFD; Heat Transfer; Modeling and Simulation; M&S