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Nagoya-shi, Japan

Oe H.,Tokyo University of Science | Yamamoto M.,Tokyo University of Science | Tanabe Y.,Japan Aerospace Exploration Agency | Sugawara H.,Ryoyu Systems Co.
34th Wind Energy Symposium | Year: 2016

This work presents the results of coupled analysis of CFD simulation of a 10MW class three-bladed rigid wind turbine with an Individual Pitch Control (IPC) system in stable Atmospheric Boundary Layer (ABL) condition without turbulence. A CFD/CSD coupling analysis code rFlow3D, developed in Japan Aerospace Exploration Agency (JAXA) originally for rotorcraft, is applied to this computation. The IPC system is a load-based feedback type, which can continuously control the pitch angle of each blade in a rated rotational frequency. This study intends to quantitatively verify the aerodynamic IPC effect for reducing fatigue load on the wind turbine which is exposed to ABL utilizing high fidelity simulation tool. For normal lift force and blade root flapwise moment, the control system effectively reduces dominant 1P fluctuation, which are caused by ABL, by 94%. 2P and higher fluctuations of blade root edgewise moment are also mitigated by more than 90% by the control effect. EFLs (Equivalent Fatigue Load) for the blade root moments are therefore largely mitigated due to the control while that for each rotor yaw and tilt moment slightly increase. These obtained results suggest that the IPC system can be sufficiently computed using CFD technique and indicate the effectiveness of IPC system to lower fatigue load on wind turbines. © 2016 American Institute of Aeronautics and Astronautics Inc, AIAA. All rights reserved. Source

Okada K.,Yokohama National University | Okada K.,Ryoyu Systems Co. | Oyama A.,Japan Aerospace Exploration Agency | Fujii K.,Japan Aerospace Exploration Agency | Miyaji K.,Yokohama National University
Transactions of the Japan Society for Aeronautical and Space Sciences | Year: 2012

This paper investigates the effects of nondimensional parameters on the characteristics of synthetic jets. Flow inside the synthetic jet cavity and orifice, the flow outside are simulated together using large-eddy simulations (LES). A comparison of the present results and those of the experiment shows that simulating the flow both inside and outside the jet cavity is essential for accurately estimating the velocity and velocity fluctuations of the synthetic jet. LES results under various flow conditions show that strong three-dimensional vortices are generated when the Reynolds number is large, but finer vortex structures form because of stronger vortex interaction as the Strouhal number increases. © 2012 The Japan Society for Aeronautical and Space Sciences. Source

Yamamoto K.,Japan Aerospace Exploration Agency | Yamamoto K.,Aviation Program Group | Tanaka K.,Japan Aerospace Exploration Agency | Tanaka K.,Ryoyu Systems Co. | And 2 more authors.
28th AIAA Applied Aerodynamics Conference | Year: 2010

Comparison study of computations for the 4th AIAA CFD Drag Prediction Workshop (DPW-IV) is performed on the NASA Common Research Model using the structured grid solver UPACS and the unstructured grid solver TAS-code. The results on the all test cases of DPW-IV (Grid convergence, Downwash, Mach sweep and Reynolds number studies) are shown and sensitivity of the drag prediction by the two different mesh methods is discussed. Additional discussion including the effect of grid resolution and the anisotropic Reynolds stress tensor on the flow separation at wing-body juncture corner for higher angle of attack and its influence on the aerodynamic performance is also described. © 2010 by the American Institute of Aeronautics and Astronautics, Inc. Source

McCallum S.,Japan Aerospace Exploration Agency | Shoji H.,Japan Aerospace Exploration Agency | Akiyama H.,Ryoyu Systems Co.
International Journal of Crashworthiness | Year: 2013

This paper presents the results of simulations used to verify the smoothed particle hydrodynamics method for bird-strike simulation and assess the influence of the bird-model shape, internal organ structure and certification configurations by comparing traditional primitive models to a new model based on biometric and published CT-scan data. Initially, a series of analyses and sensitivity studies are performed for traditional models with air porosity which show the Hugoniot pressure, steady-state pressure, impulse and force history data are in close agreement with classical hydrodynamic theory. The new model which includes eight body parts and accounts for variations in density and material strength indicates a lower Hugoniot pressure and increased asymmetry during impact. The results of the new model also show that a bird in a representative flight configuration has a longer impact duration and higher peak impact force when compared to the current folded configuration used in certification testing and simulations. © 2013 © 2013 Taylor & Francis. Source

Yamamoto K.,Japan Aerospace Exploration Agency | Tanaka K.,Ryoyu Systems Co. | Murayama M.,Japan Aerospace Exploration Agency
30th AIAA Applied Aerodynamics Conference 2012 | Year: 2012

This paper presents an improvement in numerical prediction of aerodynamic characteristics for transonic commercial aircraft using the Reynolds-averaged Navier-Stokes equations. With turbulence models base on the Boussinesq eddy-viscosity approximation, the shock-induced flow-separation at wing-body juncture-corner is sometimes overestimated at higher angle-of-attack, which often results in wrong prediction of aerodynamic force and moment of aircraft. To improve it, we focus on effect of anisotropy in the Reynolds stress at the corner flow. A simple nonlinear constitutive relation is employed to introduce the anisotropy of the Reynolds stress for the turbulence models. The obtained results show that the size of the flow separation considerably shrinks with the nonlinear model and fairly good comparison with experimental results. The detailed flow in boundary-layer at the corner is discussed for better understanding of physics that results in the improvement of prediction. © 2012 by Kazuomi Yamamoto. Source

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