Abstract:Time-step (s) ̅ Wing mean aerodynamic chord (m) , , Axial, normal and side force coefficient , , Rolling, pitching & yawing moment coefficient Subset distance (in) Store diameter, model scale (1in) Inflation layer total height (0.138in) CPU time per iteration (s)
“…Unlike the steady-state simulation, for the trajectory prediction, it can be observed that solving the viscous flow even with very well prepared meshes may not necessarily provide better results than the Euler solution. A similar observation can be made by reviewing the results of Figure 19 in Huang et al 30 Figure 30.Roll angle of the store. Comparison between the Euler and Navier–Stokes solutions for the fine mesh.Figure 31.Pitch angle of the store.…”
Section: Resultssupporting
confidence: 67%
“…For the transient run, the angular displacements results are shown in Figures 30–32 for roll, pitch, and yaw angles, respectively. The work of Huang et al 30 can be considered as a comprehensive study which analyzed the effect of the mesh (size and topology), the model scale, the wing symmetry, and the turbulence models. Their best Navier–Stokes result for angular displacements (using Spalart–Allmaras turbulence model 31 ) has been included along the work of Sunay et al 6 in these figures and compared with the present results for both Euler and Navier–Stokes simulations.…”
The ability of OpenFOAM to solve the problem of a store separating from an air vehicle (store separation problem) has been evaluated using a dynamic mesh (Overset/Chimera) technique for an industry-class (transonic and generic) benchmark test case. The major limitations of the standard libraries have been determined. To tackle these challenges, a new strategy has been proposed and implemented using only open-source libraries and tools. The strategy combines porting, modifying, and adapting an overset library from the OpenFOAM fork platform (foam-extend) to the standard OpenFOAM platform (ESI). Furthermore, in order to overcome the well-known weakness of the standard OpenFOAM compressible solvers, the newly adapted overset library was integrated with an open-source, density-based, and coupled solver ( HiSA), which uses the OpenFOAM technology. Additionally, a force restrained model was developed to consider the externally applied forces on the store by the store ejectors. The accuracy of the developed strategy has been compared with wind tunnel tests and the solutions of two well-known commercial codes, showing good agreements with them. While the study has focused on simulations with inviscid Euler equations (typical of the test case considered here), the viscosity effect on the solution has also been studied with Navier–Stokes equations and compared with other results in the literature, showing minor differences. To the best of the authors’ knowledge, this is the first work which studies and validates the store separation problem in transonic regime with OpenFOAM.
“…Unlike the steady-state simulation, for the trajectory prediction, it can be observed that solving the viscous flow even with very well prepared meshes may not necessarily provide better results than the Euler solution. A similar observation can be made by reviewing the results of Figure 19 in Huang et al 30 Figure 30.Roll angle of the store. Comparison between the Euler and Navier–Stokes solutions for the fine mesh.Figure 31.Pitch angle of the store.…”
Section: Resultssupporting
confidence: 67%
“…For the transient run, the angular displacements results are shown in Figures 30–32 for roll, pitch, and yaw angles, respectively. The work of Huang et al 30 can be considered as a comprehensive study which analyzed the effect of the mesh (size and topology), the model scale, the wing symmetry, and the turbulence models. Their best Navier–Stokes result for angular displacements (using Spalart–Allmaras turbulence model 31 ) has been included along the work of Sunay et al 6 in these figures and compared with the present results for both Euler and Navier–Stokes simulations.…”
The ability of OpenFOAM to solve the problem of a store separating from an air vehicle (store separation problem) has been evaluated using a dynamic mesh (Overset/Chimera) technique for an industry-class (transonic and generic) benchmark test case. The major limitations of the standard libraries have been determined. To tackle these challenges, a new strategy has been proposed and implemented using only open-source libraries and tools. The strategy combines porting, modifying, and adapting an overset library from the OpenFOAM fork platform (foam-extend) to the standard OpenFOAM platform (ESI). Furthermore, in order to overcome the well-known weakness of the standard OpenFOAM compressible solvers, the newly adapted overset library was integrated with an open-source, density-based, and coupled solver ( HiSA), which uses the OpenFOAM technology. Additionally, a force restrained model was developed to consider the externally applied forces on the store by the store ejectors. The accuracy of the developed strategy has been compared with wind tunnel tests and the solutions of two well-known commercial codes, showing good agreements with them. While the study has focused on simulations with inviscid Euler equations (typical of the test case considered here), the viscosity effect on the solution has also been studied with Navier–Stokes equations and compared with other results in the literature, showing minor differences. To the best of the authors’ knowledge, this is the first work which studies and validates the store separation problem in transonic regime with OpenFOAM.
A military aircraft generally includes external stores such as fuel tanks or external arming, depending on the purpose of the operation. When a store is dropped from a military aircraft at high subsonic, transonic, or supersonic speeds, the aerodynamic forces and moments acting on the store can be sufficient to send the store back into contact with the aircraft. This can cause damage to the aircraft and endanger the life of the crew. In this study, time accurate computational fluid dynamics (CFD) with dynamic moving grid (moving and deformable mesh, MDM) technique has been used to accurately calculate store trajectories. For the verification of the present numerical approach, a wind tunnel test model for the wing-pylon-finned store configuration has been considered and analyzed. The comparison results for the ejected store trajectories between the present numerical analysis and the wind tunnel test data at the Mach number of 0.95 and 1.2 are presented. It is also importantly shown that the numerical parameter of MDM technique gives significant effect for the calculated store trajectory in the low-supersonic flow such as Mach 1.2.
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