Improved-Delayed-Detached-Eddy Simulation of cavity-induced transition in hypersonic boundary layer

Xiao, Lianghua; Xiao, Zhixiang; Duan, Zhiwei; Fu, Song

doi:10.1016/j.ijheatfluidflow.2014.10.007

Cited by 53 publications

(13 citation statements)

References 30 publications

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“…31,32 Compared to the DDES grid scale, the IDDES grid scale further reduces the sub-grid viscosity in the log layer where is the air density; t is the time; u j is the velocity vector; x j is the position vector; K is the turbulent kinetic energy; and t are molecular viscosity and turbulent viscosity, respectively; and ij and S ij are the stress tensor and mean strain rate, respectively. L IDDES is the length scale for IDDES and, according to a study by Xiao et al, 33 can be defined as follows…”

Section: Methodsmentioning

confidence: 99%

Numerical simulation of the effects of obstacle deflectors on the aerodynamic performance of stationary high-speed trains at two yaw angles

Niu

Zhou

Liang

2017

Proceedings of the Institution of Mechanical Engineers, Part F:

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In this study, based on the shear-stress transport-! turbulent model, the improved delayed detached eddy simulation method has been used to simulate the unsteady aerodynamic performance of trains with different obstacle deflectors at two yaw angles (0 and 15). The numerical algorithm is used and some of the numerical results are verified through wind tunnel tests. By comparing and analysing the obtained results, the effects of the obstacle deflectors on the force of the trains as well as the pressure and flow structure around the trains are elucidated. The results show that the obstacle deflectors primarily affect the flow field at the bottom of the head car as well as the wake flow, and that the internal oblique-type obstacle deflector (IOOD) markedly improves the aerodynamic performance of the trains, by decreasing most of the aerodynamic forces of the train cars and minimising their fluctuations. Further, a nonzero yaw angle weakens or even changes the effect of the IOOD on the aerodynamic forces of the train cars. However, the effect of the IOOD is more on the tail car.

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Section: Methodsmentioning

confidence: 99%

Numerical simulation of the effects of obstacle deflectors on the aerodynamic performance of stationary high-speed trains at two yaw angles

Niu

Zhou

Liang

2017

Proceedings of the Institution of Mechanical Engineers, Part F:

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“…21,22 Compared to the DDES grid scale, the IDDES grid scale further reduces the subgrid viscosity in the log layer where ρ and μ are the density and dynamic viscosity of air at the extreme temperature (-30degC) along the Harbin–Dalian high-speed railway in Northeast China measured by Liu et al., 23 ρ=1.453kg/m3 and μ=1.57e-5Pa·s were adopted in “Results and discussion” section; t is the time; uj is the velocity vector; xj is the position vector; k is the turbulent kinetic energy; μt is the turbulent viscosity; τij and Sij are the stress tensor and mean strain rate, respectively. LIDDES is the length scale for IDDES 24 and can be defined as follows …”

Section: Numerical Detailsmentioning

confidence: 99%

A numerical study of snow accumulation on the bogies of high-speed trains based on coupling improved delayed detached eddy simulation and discrete phase model

Liu

Wang

Zhu

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part F:

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A numerical simulation method based on the improved delayed detached eddy simulation coupled with a discrete phase model is used to study the influence of the snow on the performance of bogies of a high-speed train running in snowy weather. The snow particle trajectories, mass of snow packing on the bogie, and thickness of snow accumulation have been analyzed to investigate the flow mechanisms of snow accumulation on different parts of the bogies. The results show that the snow accumulation on the first bogie of the head vehicle is almost the same as that of the second bogie, but the total accumulated snow on the top side of the second bogie is more than 74% higher than that of the first bogie. Among all the components of the bogies, the motors were found to be strongly influenced by the snow accumulation. The underlying flow mechanisms responsible for the snow accumulations are discussed.

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“…where t, k, q, u j , l, l t , s ij , and S ij are the time, turbulent kinetic energy, density, velocity, molecular viscosity, turbulent viscosity, stress tensor, and mean strain rate tensor, respectively. The L IDDES is defined as the IDDES length scale [34], given by:…”

Section: Description Of Turbulence Modelsmentioning

confidence: 99%

Effects of the pocket cavity on heat transfer and fluid flow of the downstream outlet guide vane at different flow attacking angles

Liu

Hussain

Wang

et al. 2018

Numerical Heat Transfer, Part A: Applications

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A pocket cavity is generated at the junction position of the low pressure turbine (LPT) and the outlet guide vane (OGV) in the rear part of a modern gas turbine jet engine. In the present study, a triangular pocket cavity is placed upstream of an OGV at different distances. The effects of the pocket cavity on heat transfer and fluid flow of the downstream OGV with different flow attack angles are investigated numerically with well validated turbulence models. The flow attack angles are varied as-30 , 0 , and þ30 at a constant Reynolds number ¼160,000. The turbulent flow details are provided by numerical calculations using two turbulence models, the unsteady DES model and the steady k-x SST model. For different flow attack angles, the high Nusselt number regions around the OGV are changed. The high heat transfer region is really drawn back at a flow attack angle ¼ þ30 (Case 2b) compared with Case 2a with a flow attack angle ¼0. As the flow attack angle is changed to-30 (Case 2c), the high Nusselt number regions are greatly enlarged not only on the suction side also on the pressure side because of the strengthened flow impingement on the vane surfaces. The pocket cavity weakens the flow impingement on the vane surfaces and the effect is more obvious when the pocket cavity is placed close to the vane. In addition, the heat transfer distribution over the pocket surface is also affected by the location of the vane. When the vane is placed close to the pocket cavity (Case 1), the heat transfer on the pocket edge is increased. In the case with a flow attack angle ¼0 , the high turbulent kinetic energy region is mainly located near the vane and wake region downstream the vane and recirculating flows can hardly be found.

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Improved-Delayed-Detached-Eddy Simulation of cavity-induced transition in hypersonic boundary layer

Cited by 53 publications

References 30 publications

Numerical simulation of the effects of obstacle deflectors on the aerodynamic performance of stationary high-speed trains at two yaw angles

Numerical simulation of the effects of obstacle deflectors on the aerodynamic performance of stationary high-speed trains at two yaw angles

A numerical study of snow accumulation on the bogies of high-speed trains based on coupling improved delayed detached eddy simulation and discrete phase model

Effects of the pocket cavity on heat transfer and fluid flow of the downstream outlet guide vane at different flow attacking angles

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