2018 AIAA Joint Propulsion Conference

CRAFT Tech will be well represented at the 2018 Joint Propulsion Conference in Cincinnati, Ohio (July 9-11). We will be presenting in three different topic areas

1. Numerical Framework for Simulation of Propulsive Systems at Sub-Critical Conditions presented by Dr. Ashvin Hosangadi
2. Application of a Progress Variable Based Approach For Modeling Non-Premixed/Partially Premixed Combustion Under High-Pressure Conditions presented by Dr. Balaji Muralidharan
3. Highly Compact Supersonic Inlet Design Optimization presented by Stephen Barr

In addition, Dr. Vineet Ahuja will be chairing the Modeling and Simulation of LRE and Components session on Monday, July 9th.

Title: Numerical Framework for Simulation of Propulsive Systems at Sub-Critical Conditions
Authors: Ashvin Hosangadi; Vineet Ahuja; Kevin Brinckman; Andrea C. Zambon
Session: Modeling and Simulation of LRE and Components, Monday, July 9 at 9:30AM

An advanced real-fluid numerical framework that can model thermodynamic states spanning both the supercritical and sub-critical regime near the critical point of fluids is described in this paper. The framework has been implemented within the CRUNCH CFD^® code. The framework is versatile and has been extended for multiple- species components. The applications range from phase change (condensation/cavitation) in pure fluid applications to combustion applications with cryogenic propellants. At subcritical conditions, the existence of both liquid and vapor phases at the same conditions creates a singularity in determining thermodynamic properties. This necessitates a more advanced numerical framework where the two phases are tracked independently with transport equations.  The thermodynamic properties for each phase need to extracted independently over a wide range of pressures and temperature where potentially one phase may be in a metastable state. Furthermore, phase change routines need to be developed that drive the system to equilibrium from this metastable state with appropriate thermodynamic source terms that accompany the phase change at these near critical conditions.

Title: Application of a Progress Variable Based Approach For Modeling Non-Premixed/Partially Premixed Combustion Under High-Pressure Conditions
Authors: Balaji Muralidharan; Andrea C. Zambon; Ashvin Hosangadi; William Calhoon
Session: Modeling and Simulation of Combustion I, Monday, July 9 at 3:30PM

In this paper, we report the implementation and validation of the Flamelet Generated Manifold (FGM) combustion model into our unstructured, high fidelity CFD solver, CRUNCH CFD®. The implementation extends over an existing Laminar Flamelet Model (LFM) based lookup approach that has been successfully employed in the past for investigating combustion and wall heat transfer under high-pressure conditions, e.g. in liquid rocket engines. Robustness and accuracy of the FGM approach are demonstrated by studying two canonical flame configurations: a piloted methane/air flame and a lifted methane flame. Simulation data are compared with past experimental results for validation of the developed approach. As a demonstration of the application of FGM to high-pressure conditions, a simplified setup of a gaseous $H_2$ and liquid $O_2$ supercritical combustor is investigated. The effect of resolving the finite rate effects on wall heat transfer is assessed using the current FGM and also the LFM approach. Our study indicates that FGM captures more flame unsteadiness and results in increased heat transfer from the cold reactant to some portion of the chamber wall since finite-rate chemistry effects are resolved.

Title: Highly Compact Supersonic Inlet Design Optimization
Authors: Stephen M. Barr; Michael O’Gara; Neeraj Sinha
Session: Design and Analysis of High-Speed Propulsion Systems, Wednesday, July 11 at 9:30AM

Using a modular and flexible design optimization environment, a spiked internal compression inlet design concept is optimized for maximum efficiency and minimal engine face distortion. The purpose of this paper is to illustrate the utilization of design optimization to expand the design space traditionally explored in the design of supersonic inlets while conforming to tight sizing and performance constraints. This design optimization environment was used to optimize a highly compact supersonic inlet for minimized circumferential distortion while maximizing total pressure recovery. Relative to the baseline design, the optimized inlet resulted in a 46.64% reduction in circumferential distortion and maintained an 81.6% efficiency.