Low-Reynolds number flow computation for eppler 387 wing using hybrid DES/transition model

Hwan, Jeong; Park, Soo Hyung; Kim, Chang Joo; Park, Jungkeun

doi:10.1007/s12206-015-0404-7

Cited by 20 publications

(5 citation statements)

References 16 publications

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“…The far-field boundary is located at least from the airfoil. The spanwise width of the computational domain is set to as a compromise between the spanwise extension and mesh resolution, which is suggested by other research groups (Sa et al 2015). According to a grid convergence study (as discussed below), the upper and lower surfaces of the airfoil contain 433 and 129 points, respectively.…”

Section: Resultsmentioning

confidence: 99%

Transition-based constrained large-eddy simulation method with application to an ultrahigh-lift low-pressure turbine cascade flow

Wang

Xiao

2022

J. Fluid Mech.

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A transition-predictive Reynolds-averaged Navier–Stokes (RANS) model is introduced as the Reynolds controlling condition to constrained large-eddy simulation (TrCLES) to improve the ability of this method to predict wall-bounded laminar–turbulent transition flows. In the TrCLES method, the constraint conditions for total Reynolds stress and heat flux are only imposed to the near-wall region in transitional and turbulent boundary layer. The newly proposed method recovers direct numerical simulation in the laminar boundary region, and retrieves the traditional large-eddy simulation method in the far-wall regions. The TrCLES method is validated in simulations of external flow around the Eppler 387 (E387) airfoil and internal flow past the ultrahigh-lift low-pressure turbine T106C cascade. The improved delayed detached-eddy simulation (IDDES) method, CLES method based on full-turbulence shear stress transport model and RANS method with a three-equation transition model are also evaluated in comparison with the available experimental and numerical data. As expected, the TrCLES method can predict laminar separation bubble and separation-induced transition process in both the E387 and T106C flows pretty well. In contrast, neither IDDES nor the original CLES can provide reasonable prediction for the laminar separation-induced transition phenomenon. The validity and fidelity of the TrCLES method are further verified by simulations of the T106C cascade flows in a wider range of exit Reynolds and Mach numbers. It is shown that the TrCLES method can not only predict the time-averaged aerodynamic quantities such as isentropic Mach number and exit kinetic energy loss very well, but also capture the laminar separation bubble and unsteady flow structures with satisfactory accuracy.

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Section: Resultsmentioning

confidence: 99%

Transition-based constrained large-eddy simulation method with application to an ultrahigh-lift low-pressure turbine cascade flow

Wang

Xiao

2022

J. Fluid Mech.

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“…Therefore, different models need to be employed to simulate the flow fields on different regions of the rotary-wing Mars UAVs' surface. Additionally, accurate prediction of the formation and disappearance locations of separation bubbles is crucial for the accuracy of the simulations [76,92]. Koen et al investigated the aerodynamic characteristics of rotary-wing Mars UAVs and analyzed the variation in flow field parameters around separation bubbles using an unsteady time-marching algorithm [93].…”

Section: Research On Rotor Surface Boundary Layer Separation Phenomenonmentioning

confidence: 99%

Review of Key Technologies of Rotary-Wing Mars UAVs for Mars Exploration

Zhao,

Li,

et al. 2023

Inventions

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The sparse atmosphere on the surface of Mars provides the necessary flight conditions for Mars unmanned aerial vehicles (UAVs) to perform low-altitude flights. This work presents a comprehensive overview of key technologies in the development of Mars UAVs, with a specific focus on rotary-wing Mars UAVs. It summarizes prototypes of rotary-wing Mars UAVs developed by various global research institutions. It reviews essential technologies in rotary-wing Mars UAV research, including the Mars near-surface atmospheric environment, aerodynamic characteristics, and principles of low-pressure flight control. This work also summarizes various experimental setups and ground test results for rotary-wing Mars UAVs. Furthermore, it discusses the future development trends of rotary-wing Mars UAVs.

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“…This was certainly the typical operating condition of the H-Darrieus rotor in the present work. This option was studied by Sa et al [30] on the flow past an Eppler 387 wing. The results indicated that the hybrid DES/Transition model predicted both strong laminar/turbulent transition phenomena, including the laminar separation bubble, and flow separation at high angles of attack.…”

Section: Literature Backgroundmentioning

confidence: 99%

Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

et al. 2020

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The simulation of very small vertical axis wind turbines is often a complex task due to the very low Reynolds number effects and the strong unsteadiness related to the rotor operation. Moreover, the high boundary layer instabilities, which affect these turbines, strongly limits their efficiency compared to micro horizontal axis wind turbines. However, as the scientific interest toward micro wind turbine power generation is growing for powering small stand-alone devices, Vertical Axis Wind Turbines (VAWTs)might be very suitable for this kind of application as well. Furthermore, micro wind turbines are widely used for wind tunnel testing, as the wind tunnel dimensions are usually quite limited. In order to obtain a better comprehension of the fluid dynamics of such micro rotors, in the present paper the authors demonstrate how to develop an accurate CFD 2D model of a micro H-Darrieus wind turbine, inherently characterized by highly unstable operating conditions. The rotor was tested in the subsonic wind tunnel, owned by the University of Catania, in order to obtain the experimental validation of the numerical model. The modeling methodology was developed by means of an accurate grid and time step sensitivity study and by comparing different approaches for the turbulence closure. The hybrid LES/RANS Delayed Detached Eddy Simulation, coupled to a transition model, demonstrated superior accuracy compared to the most advanced unsteady RANS models. Therefore, the CFD 2D model developed in this work allowed for a thorough insight into the unstable fluid dynamic operating conditions of micro VAWTs, leading the way for the performance improvement of such rotors.

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Low-Reynolds number flow computation for eppler 387 wing using hybrid DES/transition model

Cited by 20 publications

References 16 publications

Transition-based constrained large-eddy simulation method with application to an ultrahigh-lift low-pressure turbine cascade flow

Transition-based constrained large-eddy simulation method with application to an ultrahigh-lift low-pressure turbine cascade flow

Review of Key Technologies of Rotary-Wing Mars UAVs for Mars Exploration

Development and Validation of CFD 2D Models for the Simulation of Micro H-Darrieus Turbines Subjected to High Boundary Layer Instabilities

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