Ryoyu Systems Co.

Nagoya-shi, Japan

Ryoyu Systems Co.

Nagoya-shi, Japan

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Tanabe Y.,Japan Aerospace Exploration Agency | Sugawara H.,Ryoyu Systems Inc. Ltd.
5th Asian-Australian Rotorcraft Forum, ARF 2016 | Year: 2016

A numerical simulation of the rotor/wing aerodynamic interaction in hover using rotorcraft CFD solver, rFlow3D, is described. The wing download caused by the rotor downwash is studied under various rotor thrust, with and without wing flap and at different distances between the rotor and the wing, and the results are compared with the experimental data by NASA. The computational results of wing download are overestimated, but the trends are predicted qualitatively in good agreement with the experimental data except in the case of distance between the rotor and the wing. The rotor performance changes due to the wing are predicted in good agreement with the ground effect with consideration of rotor and wing area ratio. Copyright © 2016 by the American Helicopter Society International, Inc. All rights reserved.

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.

Imamura T.,Japan Aerospace Exploration Agency | Hirai T.,Ryoyu Systems Co. | Enomoto S.,Japan Aerospace Exploration Agency | Yamamoto K.,Japan Aerospace Exploration Agency
17th AIAA/CEAS Aeroacoustics Conference 2011 (32nd AIAA Aeroacoustics Conference) | Year: 2011

Flow around tandem cylinder is solved using UPACS-LES code developed in JAXA. Delayed detached-eddy-simulation (DDES) is used, and order of numerical schemes and grid density are changed to investigate their sensitivities to the near-field flow and far-field noise. The results are compared with the experimental results. It became apparent that near-field flow structures including both steady and unsteady components are sensitive to the numerical scheme and grid density. As spatial resolution is increased, the results tend to converge toward the experimental results. On the other hand, far-field noise is insensitive to the spatial resolution. The dominant noise is generated by the impingement of the upstream cylinder wake on the downstream cylinder, and this large scale feature is already captured by the lowest spatial resolution case which we have calculated. The highest resolution case with long spanwise length (18D) shows good agreement in terms of both tonal and broadband component. © 2011 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Takii K.,Tokyo Metroplitan University | Kanazaki M.,Tokyo Metroplitan University | Ishiko K.,Japan Aerospace Exploration Agency | Atsushi K.H.,Ryoyu Systems Co. | And 2 more authors.
52nd Aerospace Sciences Meeting | Year: 2014

In this study, the numerical simulations of three-dimensional flow overa reentry capsule of HTV-R are carried out using detached-eddy simulation (DES). Firstly, the obtained aerodynamic coefficients are compared with wind tunnel data obtained by use of experimental facilities in Japan Aerospace Exploration Agency(JAXA). The aerodynamic coefficients obtained by DES at Mach number M=0.8 and 1.1 give good agreement with those obtained in experiments, but not at Much number M=0.4 and 0.6. Compared to flow fields obtained by RANS, it is found that the surface pressure obtained by DES differs from that obtained by RANS. The lower surface pressure region appears around the upper shoulder or RANS correspondingto the circulation flow, but not for DES. Secondary, time-series analysis of aerodynamic coefficients is performed and the obtainedStrouhal number sare close to 0.2 for all Mach numbers. © 2015 American Institute of Aeronautics and Astronautics Inc. All rights reserved.

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.

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.

Tanabe Y.,Japan Aerospace Exploration Agency | Sugawara H.,Ryoyu Systems Co.
41st European Rotorcraft Forum 2015, ERF 2015 | Year: 2015

Validation of the rFlow3D code developed at Japan Aerospace Exploration Agency (JAXA) has been carried out with the published UH-60A test data in hover and forward flight. Also, the slowed rotor conditions are simulated to investigate the applicability of this code at high advance ratios. Although the elastic deformation of the blade is not considered at this point, good agreement of the aerodynamic performance is obtained compared with the experimental data. Extensions of the CFD solver toward complete compound helicopter simulations are also discussed.

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.

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.

Murayama M.,Japan Aerospace Exploration Agency | Yokokawa Y.,Japan Aerospace Exploration Agency | Yamamoto K.,Japan Aerospace Exploration Agency | Hirai T.,Ryoyu Systems Co.
Computers and Fluids | Year: 2013

The purpose of this paper is computational investigation of flowfield related to two types of low noise devices for noise from tire-axle region of a two-wheel main landing gear. The detailed unsteady flowfield around complicated geometry of tire-axle regions and its relation to noise generation are identified by unsteady CFD computations for the baseline configuration without low-noise devices. Then, the changes of flow structure related to possible noise sources by two types of low-noise fairings using solid surface and porous surface around the tire-axle region are clarified by steady CFD computations. By the computations, the design knowledge of low noise fairings around tire-axle region of a two-wheel main landing gear is investigated. © 2012 Elsevier Ltd.

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