Accuracy and Performance Improvements to Kestrel’s Near-Body Flow Solver

McDaniel, David R.; Nichols, R.; Eymann, Timothy A.; Starr, Robert E.; Morton, Scott A.

doi:10.2514/6.2016-1051

“…The code then solves unsteady, three-dimensional, compressible RANS equations on hybrid unstructured grids [13]. The code uses the Method of Lines (MOL) to separate temporal and spatial integration schemes from each other [14]. The spatial residual is computed via a Godunov type scheme [15].…”

Section: Cfd Solvermentioning

confidence: 99%

Computational Study of Propeller Wing Aerodynamic Interaction

Aref

¹

,

Ghoreyshi

²

,

Jirasek

³

et al. 2018

2018 AIAA Aerospace Sciences Meeting

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Kestrel simulation tools are used to investigate the mutual interference between the propeller and wing of C130J aircraft. Only the wing, nacelles, and propeller geometries are considered. The propulsion system modelled is a Dowty six-bladed R391 propeller mounted at inboard or outboard wing sections in single and dual propeller configurations. The results show that installed propeller configurations have asymmetric blade loadings such that downward-moving blades produce more thrust force than those moving upward. In addition, the influence of installed propeller flow-fields on the wing aerodynamic (pressure coefficient and local lift distribution) are investigated. The installed propeller configuration data are compared with the non-installed case, and the results show that propeller effects will improve the wing's lift distribution. The increase in lift behind the propeller is different at the left and right sides of the propeller. In addition, the propeller helps to delay the wing flow separation behind it for tested conditions of this work. Finally, the results show the capability of Kestrel simulation tools for modeling and design of propellers and investigates their effects over aircraft during conceptual design in which no experimental or flight test data are available yet. This will lead to reducing the number of tests required later.Aerospace 2018, 5, 79 2 of 20 concepts and thus the design of these vehicles would be helped by the early availability of high quality computational models to allow control laws to be defined.Advances in computational modeling of propellers are reported in literature [3]. In a simple manner, propellers may be physically replaced with thin actuator disks using Froude-Rankine momentum theory. This approach assumes an infinite number of thin propeller blades and inviscid flow through the disk. The model then should ensure the mass flow continuity between front and rear faces of disk. Depending on the input thrust and rotational speed, the rear face will have a jump in total pressure, total temperature, and velocity. Advanced computational methods of sliding interfaces, Chimera or overset grids have been used for propeller flow simulations as well [4][5][6][7]. Results of such simulations have compared well with available wind tunnel data. Periodic slipstream unsteadiness has been captured in wing lift and drag, and increased suction peaks at the wing leading edge have also been documented for wing mounted engines. In addition to propeller slipstream interaction with the wing, other components of the aircraft may also be affected by the local unsteadiness depending on relative position of the propeller and the aircraft component. It is well known for traditional single engine aircraft, the wake-fuselage and wake-tail interactions are significant at high power and low airspeed configurations, such as during takeoff. For these conditions, the aircraft experiences a yaw to the left if no control input is made to counter the resultant force. In addition, at high angles of attack, asy...

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“…Reynolds-averaged Navier-Stokes calculations are preferred in engineering design, in spite of their poor accuracy at hypersonic conditions (Wilcox 2006) and sensitivity to model parameters (Roys & Blottner 2006). To overcome these problems especially in the hypersonic regime, recent studies proposed compressibility corrections (McDaniel et al 2016;Nichols 2019;Danis & Durbin 2022;Hendrickson, Subbareddy & Candler 2022) reporting significant improvements. The non-eddy-resolving nature of RANS makes their adoption in highly unsteady flows such as shock-boundary layer interaction problems also challenging (Wadhams, Holden & Maclean 2014).…”

Section: Motivationmentioning

confidence: 99%

Sub-filter-scale shear stress analysis in hypersonic turbulent Couette flow

Toki,

Sousa,

Chen

et al. 2024

J. Fluid Mech.

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Direct numerical simulations of hypersonic turbulent Couette flows are performed for top-wall Mach numbers of 6, 7 and 8, inspired by non-reactive high-enthalpy wind tunnel free-stream conditions, with the goal of analysing the physical processes driving the sub-filter-scale (SFS) stresses to inform development of large-eddy simulation techniques for hypersonic wall-bounded flows. Semi-local scaling laws collapse mean profiles and second-order turbulent statistics well, in spite of the strong wall-normal gradients of temperature and density. On the other hand, the SFS shear stresses exhibit an unexpected profile characterized by a region of pronounced shear stress deficit, which becomes more pronounced for higher Mach numbers. Instantaneous visualizations suggest that the SFS shear stress deficit is induced by the counter-gradient resolved momentum transport driven by residual velocity motions at the interface between high-density low-speed streaks being ejected away from the wall, and low-density high-speed ones replacing the displaced fluid, qualifying this as a compressibility effect. It is shown that the SFS shear stresses are primarily driven by second-order interactions between residual velocities, in spite of their triply nonlinear nature. This, in turn, motivated a statistical quadrant analysis revealing the presence of a SFS shear stress deficit, that is, SFS processes driving momentum transport of the resolved field towards the top wall. Additionally, higher-Reynolds-number simulations reveal that there is an upper limit of spatial filter widths to resolve large-scale structures, and such deficit is observable at any Reynolds number when a reasonable spatial filter is applied.

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“…The code then solves unsteady, three-dimensional, compressible RANS equations on hybrid unstructured grids [13]. The code uses the Method of Lines (MOL) to separate temporal and spatial integration schemes from each other [14]. The spatial residual is computed via a Godunov type scheme [15].…”

Section: Cfd Solvermentioning

confidence: 99%

Computational Study of Propeller–Wing Aerodynamic Interaction

Aref

¹

,

Ghoreyshi

²

,

Jirasek

³

et al. 2018

View full text Add to dashboard Cite

Kestrel simulation tools are used to investigate the mutual interference between the propeller and wing of C130J aircraft. Only the wing, nacelles, and propeller geometries are considered. The propulsion system modelled is a Dowty six-bladed R391 propeller mounted at inboard or outboard wing sections in single and dual propeller configurations. The results show that installed propeller configurations have asymmetric blade loadings such that downward-moving blades produce more thrust force than those moving upward. In addition, the influence of installed propeller flow-fields on the wing aerodynamic (pressure coefficient and local lift distribution) are investigated. The installed propeller configuration data are compared with the non-installed case, and the results show that propeller effects will improve the wing's lift distribution. The increase in lift behind the propeller is different at the left and right sides of the propeller. In addition, the propeller helps to delay the wing flow separation behind it for tested conditions of this work. Finally, the results show the capability of Kestrel simulation tools for modeling and design of propellers and investigates their effects over aircraft during conceptual design in which no experimental or flight test data are available yet. This will lead to reducing the number of tests required later.

show abstract

Accuracy and Performance Improvements to Kestrel’s Near-Body Flow Solver

Cited by 62 publications

References 29 publications

Computational Study of Propeller Wing Aerodynamic Interaction

Computational Study of Propeller Wing Aerodynamic Interaction

Sub-filter-scale shear stress analysis in hypersonic turbulent Couette flow

Computational Study of Propeller–Wing Aerodynamic Interaction

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