Validation of Inlet and Exhaust Boundary Conditions for a Cartesian Method

Pandya, Shishir A.; Murman, Scott M.; Aftosmis, Michael J.

doi:10.2514/6.2004-4837

Cited by 15 publications

(7 citation statements)

References 10 publications

(17 reference statements)

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“…We use primitive variables to simplify the presentation. The full implementation and discussion of these boundary conditions is given by Rodriguez et al, 14 extending earlier work by Pandya et al 24 Here we give only the main results to set the stage for discussing the corresponding adjoint, or dual, boundary conditions in Section V. For subsonic outflow through the wetted surface, e.g., when simulating engine inlets, the boundary state is constructed from one user-specified quantity, either exit pressure p set or normal velocity U n,set . All other quantities are taken from the interior, i.e., from within the computational domain.…”

Section: Methodsmentioning

confidence: 81%

Adjoint-Based Mesh Adaptation and Shape Optimization for Simulations with Propulsion

Nemec

Rodriguez²,

Aftosmis

2019

AIAA Aviation 2019 Forum

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We demonstrate a well-posed formulation of permeable boundary conditions and massflow-rate functionals for adjoint-based mesh refinement and shape optimization governed by the steady Euler equations. The boundary conditions are used to model propulsionsystem effects of inlets and nozzles. A two-shock diffuser with an analytic solution is used to verify the implementation. Numerical examples show that the adjoint solution is smooth at the boundary, indicating that the discretization is adjoint consistent when exit pressure is specified at subsonic outflow, and stagnation temperature and pressure at subsonic inflow. The results focus on improving simulation techniques for low-boom aircraft analysis and design. By including mass-flow-rate outputs, we obtain reliable estimates of engine flow rates concurrently with nearfield pressure signatures without increasing simulation cost. We also demonstrate the importance of mass-flow-rate constraints in shape optimization by examining trade-offs between maximizing performance of a shrouded supersonic nozzle and minimizing shocks in its nearfield.

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Section: Methodsmentioning

confidence: 81%

Adjoint-Based Mesh Adaptation and Shape Optimization for Simulations with Propulsion

Nemec

Rodriguez²,

Aftosmis

2019

AIAA Aviation 2019 Forum

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“…4 This type of boundary condition is not available in the inviscid solver, so plumes are modeled with uniform inflow boundary conditions at the nozzle throat, and the flow solver is responsible for producing the correct nozzle exit profile. 7 The Cart3D flow solver is constrained to a single-species perfect gas assumption. Isentropic flow relations are used to adjust the nozzle throat diameter and mean flow nozzle conditions.…”

Section: Nozzle Boundary Conditionsmentioning

confidence: 99%

Aerodynamic Database Generation for SRB Separation from a Heavy Lift Launch Vehicle

Gusman

Kiris

Barad

2011

29th AIAA Applied Aerodynamics Conference

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An engineering approach is presented for database generation of aerodynamic force and moment coefficients on Solid Rocket Boosters (SRBs) during separation from a Heavy Lift Launch Vehicle. The approach balances accuracy and affordability by generating a steadystate database of solutions using the inviscid flow solver Cart3D with adjoint based adaptive mesh refinement. The procedure also includes point checking the database using the viscous Reynolds Averaged Navier-Stokes solver OVERFLOW. The simulation matrix consists of 3 degrees of freedom by planar translation and rotation of the SRBs from their original attached positions. Good agreement with viscous multi-species simulations has confirmed that the single-species inviscid assumptions are valid for this plume impingement flow. The database provides axial forces, side forces, and yaw moments on the SRBs during separation from the core. This data is to be used for vehicle and trajectory planning to avoid re-contacting the core. Nomenclature β Rotation angle (degrees) HLLV Heavy Lift Launch Vehicle γ Ratio of specific heats M Mach number ∆x Translation downstream (normalized) P Pressure (Pa) ∆y Translation cross-stream (normalized) SRB Solid Rocket Booster ρ Density (kg/m 3) V Velocity (m/s) A Area of nozzle cross-section (m 2) c Speed of sound (m/s) CA Axial force coefficient CG Center of Gravity CLN Yaw moment coefficient CY Side force coefficient F&M Force and Moment

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“…These studies mainly focused on flow behavior inside and downstream of exhaust nozzle, whereas, the actual nozzle flow characteristics and performance is quite different when propulsion system and aircraft external flow interaction with exhaust plume is taken into account. Effect of jet exhaust plume on control surfaces of aircraft and change in pitching and yawing moments are also important in determining the stability parameters of aircraft (Pandya, et al 2004).…”

Section: Introductionmentioning

confidence: 99%

Computational Analysis of Integrated Engine Exhaust Nozzle on a Supersonic Fighter Aircraft

Arif

Masud

Shah

2018

JAFM

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A unique approach of analyzing jet exhaust nozzle integrated to aircraft and propulsion system is presented in this paper. Engine exhaust nozzle is usually omitted in Wind Tunnel Testing and numerical analysis of aircraft due to complexities involved in integration of nozzle and presence of high pressure / temperature inside exhaust nozzle. Also, the flow properties are non-uniform and highly turbulent in the vicinity of nozzle. Therefore, exhaust nozzle is usually analyzed in isolation and these results often lead to inaccuracies from actual scenario where nozzle is integrated with aircraft and its propulsion system. This research aims to integrate engine exhaust nozzle on a supersonic fighter aircraft and analyze its flow characteristics and variation in performance parameters due to its integration. Engine propulsion characteristics and parameters such as nozzle inlet temperature and total pressure have been analyzed through an in-house validated engine analytical model developed by some of the authors of this study. In the first part of paper, exhaust plume structure has been analyzed to study the flow behaviour (flow turbulence and flow distortion etc) at nozzle exit. Later, nozzle performance parameters such as Exit Velocity, Nozzle Pressure Ratio (NPR), Engine Pressure Ratio (EPR), and Engine Temperature Ratio (ETR) have been calculated when exhaust nozzle is integrated with the aircraft. Finally, the results are compared and validated with analytical calculations to compare the performance of nozzle when it is in isolation and when it is integrated on aircraft. It is observed that nozzle flow has no significant effect on aircraft major surfaces such as fuselage, wing upper and lower surfaces, and nose section. However, there is a prominent effect of exhaust nozzle flow on horizontal stabilizers, vertical tail and rear fuselage area of the aircraft. An average difference of 18% in NPR, 12% in EPR, and 9% in ETR is observed between integrated nozzle and isolated nozzle which further signifies the importance of integrating exhaust nozzle in aircraft analysis. This proposed methodology will allow more accurate analysis of the effects of exhaust nozzle on the overall performance of aircraft. The methodology can further be used for proposing design changes in existing nozzle configurations.

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Validation of Inlet and Exhaust Boundary Conditions for a Cartesian Method

Cited by 15 publications

References 10 publications

Adjoint-Based Mesh Adaptation and Shape Optimization for Simulations with Propulsion

Adjoint-Based Mesh Adaptation and Shape Optimization for Simulations with Propulsion

Aerodynamic Database Generation for SRB Separation from a Heavy Lift Launch Vehicle

Computational Analysis of Integrated Engine Exhaust Nozzle on a Supersonic Fighter Aircraft

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