Browsing by Author "Zeng, Kai"
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Item Open Access Computational analysis and design of an aerofoil with morphing tail for improved aerodynamic performance in transonic regime(Cambridge University Press, 2022-01-10) Rana, Zeeshan; Mauret, F.; Sanchez-Gil, J. M.; Zeng, Kai; Hou, Z.; Dayyani, Iman; Könözsy, László Z.This article focuses on the aerodynamic design of a morphing aerofoil at cruise conditions using computational fluid dynamics (CFD). The morphing aerofoil has been analysed at a Mach number of 0.8 and Reynolds number of 3×106 , which represents the transonic cruise speed of a commercial aircraft. In this research, the NACA0012 aerofoil has been identified as the baseline aerofoil where the analysis has been performed under steady conditions at a range of angles of attack between 0∘ and 3.86∘ . The performance of the baseline case has been compared to the morphing aerofoil for different morphing deflections ( wte/c=[0.005−0.1] ) and start of the morphing locations ( xs/c=[0.65−0.80] ). Further, the location of the shock wave on the upper surface has also been investigated due to concerns about the structural integrity of the morphing part of the aerofoil. Based upon this investigation, a most favourable morphed geometry has been presented that offers both, a significant increase in the lift-to-drag ratio against its un-morphed counterpart and has a shock location upstream of the start of the morphing part.Item Open Access Implicit large eddy simulations of turbulent flow around a square cylinder at Re=22,000(Elsevier, 2021-05-07) Zeng, Kai; Li, Zhuoneng; Rana, Zeeshan A.; Jenkins, Karl W.In this paper, the Implicit Large-Eddy Simulation (ILES) is investigated on the flow around a square cylinder incorporating an unstructured Weighted Essential Non-Oscillatory (WENO) reconstruction method for a Reynolds number of 22,000. Simulations are undertaken in the framework of open-source package OpenFOAM and additional implicit 2nd/3rd-order WENO scheme on the convective term of the viscous incompressible Navier-Stokes Equations. A 2nd-order Euler implicit time integration and Pressure-Implicit Splitting-Operator (PISO) algorithm is used to for the pressure-velocity coupling. Conventional LES with Wall Adapting Local Eddy Viscosity (WALE) model is also carried out as a baseline. The results are compared to high fidelity experiment, DNS data and conventional LES with dynamic Smagorinsky model from previous work. Results show favorable performance for ILES with 3rd-order WENO scheme compared with the conventional LES with dynamic Smagorinsky model and similar performance against LES with WALE model. Results also show acceptable predictions over time-averaged statistics with less computational effort for the ILES of 2nd-order WENO scheme. Shear layer flow analysis suggests that both ILES and LES face similar challenges with small quantities, such as shear stress. Finally, simulations are capturing Von Krmn vortex, Kelvin-Helmholtz instability and induced frequency changes.