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Ishiko K.,Japan Aerospace Exploration Agency | Ishiko K.,Institute of Aeronautical Technology | Hashimoto A.,Japan Aerospace Exploration Agency | Hashimoto A.,Institute of Aeronautical Technology | And 7 more authors.
Journal of Aircraft | Year: 2014

To predict the flowfield of three-dimensional wall jets, an extended nonlinear constitutive relation is incorporated into the Spalart-Allmaras turbulence model.Amodification of the model is made to improve the predictability of free jets. The FaST aerodynamic routines code, developed at the Japan Aerospace Exploration Agency, is used as a compressible-flow solver. First, a turbulent boundary-layer flow along a flat plate is computed to confirm the validity of the extended nonlinear constitutive relation. The obtained logarithmic velocity profile agrees well with the analytical solution. As a result, the modification is confirmed to have no adverse effects on the prediction of the typical wall-bounded flow. Second, computations of three-dimensional free and wall jets are performed, the results of which are compared with observations of the velocity field up to the far region from the jet nozzle exit, which are made by the experimental facility of Nagoya University. In free jets, reasonable computed results are obtained with respect to the streamwise decay and the half-width of the velocity, confirming the applicability of the modification to free jets. In wall jets, the modified model properly reproduces the secondary flow observed in the experiment, and its qualitative success is shown by the conservation of momentum. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.

Hashimoto A.,Japan Aerospace Exploration Agency | Hashimoto A.,Institute of Aeronautical Technology | Murayama M.,Japan Aerospace Exploration Agency | Murayama M.,Institute of Aeronautical Technology | And 5 more authors.
52nd Aerospace Sciences Meeting | Year: 2014

JAXA’s two CFD codes, FaSTAR and UPACS, are verified on the common test cases and their convergence performances are demonstrated. FaSTAR is an unstructured-grid flow solver and UPACS is a structured-grid one. In this paper, the simple two test cases are studied: 2D zero pressure gradient flat plate and 2D NACA 0012 airfoil. First, we verify that our codes solve the flow equations properly with satisfactory accuracy. The results of FaSTAR and UPACS show the similar trend and agree well with those of CFL3D. Then convergence histories of aerodynamic coefficients and residuals are shown. The single-grid and multigrid convergences are almost same between FaSTAR and UPACS. Additionally, the practical problems such as NASA-CRM and DLR-F11 are studied. The current performance of multigrid is demonstrated and related issues are discussed. © 2014, American Institute of Aeronautics and Astronautics Inc. All rights reserved.

Fisch G.,Brazilian Technological Institute of Aeronautics | Da Silva A.F.G.,Institute of Aeronautical Technology | Iriart P.G.,Brazilian Technological Institute of Aeronautics
European Space Agency, (Special Publication) ESA SP | Year: 2013

The determination of the winds (both at surface and upper air) at a Space Launching Center is crucial for the safety in a rocket launching. The wind profile can be used for the determination of the flight trajectory as well as to predict the dispersion of the plume released by the gases exhausted during the lift-off. The mesoscale model WRF (Weather Research and Forecasting) is the state-of-art in terms of atmospheric model and it can be used to forecast all the climatic elements, specially the winds. So, the goal of this paper is to investigate the use of the model WRF at the Centro de Lançamento de Alcântara (CLA), which is the Brazilian access to the space, to provide forecast winds information to the Operational Flight Coordinator. The validation was made through out comparisons between outputs of the model and wind measurements. The observations were made at CLA by rawinsoundings released each 6 hours during 10 days period in the dry season 2008 and wet season 2010. The model WRF-ARW (version 3.2.1) was tested for a domain centered at the CLA. The configuration of the runs was 3 grid nested with a resolution of 9, 3 and 1 km, respectively and 40 vertical levels. The wind forecast for 72 hours were made with initial data-set from GFS (Global Forecasting System, which is the operational analysis from NCEP), starting at 00 and 12 UTC for both periods. The statistical metrics used were Wilmott indexes; bias and square mean error, computing from the differences between the outputs from the model and observations up to a height of 5000 m (ballistic winds). From the boundary layer parameterizations tested (ACM2, MYNN2, 5, ETA and YSU), the ACM2 and MYNN2, 5 gave the best results for the dry and wet season, respectively. The model WRF was able to represented, reasonable and within the limit of 1 m/s, the wind profile up to 36 hour, for both periods (dry and wet). Also, there is no difference if the simulation started at 00 or 12 UTC. In order to verify the influence of the initial input data, 4 simulations (2 for each season) were made with GFS (analysis) and FNL (re-analysis). The results did not show any significant difference, concluding that it is possible to use the GFS (which is operational) for the simulations during a launching operation. In summary, the model WRF was proved to be useful for a rocket flight providing winds in advance.

Yokozeki T.,University of Tokyo | Sugiura A.,University of Tokyo | Hirano Y.,Japan Aerospace Exploration Agency | Hirano Y.,Institute of Aeronautical Technology
22nd AIAA/ASME/AHS Adaptive Structures Conference | Year: 2014

This paper describes the development and the wind tunnel test of a variable geometry morphing airfoil using corrugated structures. Proof-of-concept study of a morphing wing with flexible seamless flap-like structure is performed by the finite element analysis. For the actuation system, two servomotors are installed inside the prototype wing to control the airfoil shape by the chord-wise tension of the connected wires. Successful actuation of the prototype wing is demonstrated under the air speed up to 30 m/s in the wind tunnel test.

Chertovskih R.,Institute of Aeronautical Technology | Zheligovsky V.,Prediction Institute
Physica D: Nonlinear Phenomena | Year: 2015

We present a new mechanism for generation of large-scale magnetic field by thermal convection which does not involve the α-effect. We consider weakly nonlinear perturbations of space-periodic steady convective magnetic dynamos in a rotating layer of incompressible electrically conducting fluid that were identified in our previous work. The perturbations have a spatial scale in the horizontal direction that is much larger than the period of the perturbed convective magnetohydrodynamic state. Following the formalism of the multiscale stability theory, we have derived the system of amplitude equations governing the evolution of the leading terms in the expansion of the perturbations in power series in the scale ratio. This asymptotic analysis is more involved than in the cases considered earlier, because the kernel of the operator of linearisation has zero-mean neutral modes whose origin lies in the spatial invariance of the perturbed regime, the operator reduced on the generalised kernel has two Jordan normal form blocks of size two, and simplifying symmetries of the perturbed state are now missing. Numerical results for the amplitude equations show that a large-scale perturbation, periodic in slow horizontal variable, either converges to a small-scale neutral stability mode with amplitudes tending to constant values, or it blows up at a finite slow time. © 2015 Elsevier B.V. All rights reserved.

Fisch G.,Brazilian Technological Institute of Aeronautics | Leao R.C.,Brazilian Technological Institute of Aeronautics | Vendrame I.F.,Institute of Aeronautical Technology
European Space Agency, (Special Publication) ESA SP | Year: 2011

The winds at lower (inside the surface layer ranging from the surface up to 120-150 m) and upper atmosphère (up to 20 km) are very important to determine the flight trajectory of the rockets. At the Space Launching Centers they are usually measured by wind or anemometric tower (lower winds) and from rawinsoundings (upper winds). These two measurements are used to compute the ballistic winds without any attempt or technique to match the two profiles. This work has been done in order to propose a technique to adjust and match the two different vertical profiles of wind at the Brazilian Space Launching Center. The winds from the lower part is characterized by an anemometric tower while the upper air winds were determined from the rawinsounding system (Vaisala, Finland) using the Global Positioning System technique (GPS). These two wind profiles were matched together using an interpolation method (cubic spline) in order to avoid the abrupt changes in the average profile. This paper described the method used and applied for a simulation with a sounding rocket (VSB30) launched from Alcantara Space Center (ASC) during the 2005 dry season (period when the winds are stronger). The results showed that this new and adjusted wind profile has determined the impact point better than the usual method used (no adjustment). The impact point has moved 2.4 km with the proposed method although within the dispersion area (usually accepted as 40 km of radius). The apogee (higher by 0.3 km) and the slant range (reduced by 0.9 km) also changed due to the different initial conditions.

Araki M.,Gunma University | Ijuin Y.,Gunma University | Nishida S.,Japan Aerospace Exploration Agency | Nishida S.,Institute of Aeronautical Technology | And 4 more authors.
Journal of Propulsion and Power | Year: 2014

Mean-flow and acoustic characteristics of cold-air jets issuing from a rectangular hypersonic nozzle were investigated experimentally. The final goal of this study is (even though qualitative to some extent) to establish a method capable of predicting the acoustic characteristics of the high-temperature and high-velocity jets issuing from a hypersonic engine. As the first step, a high-enthalpy wind-tunnel plant without anechoic treatment was used for the cold-air jet experiments, and the acoustic data obtained were compared with those obtained in a small anechoic chamber. It is shown that, while it is necessary to pay attention to some noted exceptions, the directivity patterns and spectral shapes agree well at a wide range of radiation angles by taking into account the correction of -2.5 dB. The mean-flow measurements revealed that, due to the complicated geometry of the nozzle, the jet has a highly asymmetric velocity profile at the ramp end and that the development of the jet plume is also inclined and asymmetric, which resulted in the complicated patterns of the acoustic radiation. By fitting the sound spectra for the large turbulence structure noise and fine-scale turbulence noise, the contributions of the two noise sources in the hypersonic nozzle were investigated. © 2012 AIAA.

Enomoto S.,Japan Aerospace Exploration Agency | Enomoto S.,Tokyo Institute of Technology | Yamamoto K.,Japan Aerospace Exploration Agency | Yamamoto K.,Institute of Aeronautical Technology | And 2 more authors.
20th AIAA/CEAS Aeroacoustics Conference | Year: 2014

Research of jet noise reduction by adaptive microjets injection has been conducted under a collaborative research project between Onera, Snecma, IHI, and JAXA. The first paper of this collaborative research was about the microjets noise reduction on a low bypass ratio engine nozzle (Tanaka et al., AIAA 2012-2300). Here we present the experimental and numerical results of a microjet noise reduction on a high bypass ratio (HBPR) double stream nozzle model with and without pylon, tested at the Martel test facility in France. Snecma conducted a microjets noise reduction test, and JAXA took charge of Large Eddy Simulations (LES) to show the current noise prediction capability. The purposes of this research were the development of a noise suppression technology for double stream jet nozzle using microjets, and the acquisition of noise prediction technology for jet noise with low noise devices.

Araki M.,Gunma University | Araki M.,Division 5 Technology | Morita K.,Gunma University | Takahashi Y.,Gunma University | And 6 more authors.
AIAA Journal | Year: 2015

The behavior of the noises sources in the exhaust jet issuing from a rectangular hypersonic nozzle operating at takeoff condition were investigated experimentally The working gas was cold air, and the NPR was set at 2.70. By use of schlieren optics, the density gradient fluctuation in the jet and its acoustic field were detected as the variation of the light intensity. In the data obtained with the schlieren optics, intensive fluctuation of the light intensity is observed in the entire region of the jet. By use of cross-correlation analysis between the light intensity fluctuation and the far-field noise, a relatively large cross correlation is obtained. From the local maximum cross correlation, it is considered that, both at the ramp and cowl sides, the major source for the far-field noise at downstream angles exists in the upper shear layer of the initial free jet region because of the rapid mixing due to the steep velocity gradient. Regarding the cowl side, a relatively large cross correlation for the sideline microphones is also observed in the semi-confined jet region on the ramp.

Araki M.,Gunma University | Ijuin Y.,Gunma University | Nishida S.,Japan Aerospace Exploration Agency | Nishida S.,Institute of Aeronautical Technology | And 5 more authors.
Journal of Propulsion and Power | Year: 2014

Acoustic simulation of hot jets issuing from a rectangular hypersonic nozzle was carried out. The aim of this study is, even though qualitative to some extent, to establish a method capable of predicting the acoustic characteristics of the high-temperature and high-velocity jets issuing from the realistic hypersonic nozzle having a complicated geometry. Two kinds of test nozzles, 2.4% scaled model with afterburner for hot jet experiments and 1.0% scaled model for cold-air/helium mixture jet experiments, were manufactured and tested. By using a high-enthalpy windtunnel plant, acoustic characteristics of the hot jets issuing from the rectangular hypersonic nozzle for several representative but realistic high-temperature and high-velocity jet conditions were obtained. At the same time, by using a small anechoic chamber, the acoustic characteristics of the hot jets were duplicated using cold-air/helium mixture jets having the same velocities. Although we have to pay attention to some noted exceptions, the directivity patterns and the spectral shapes for cold-air/heliummixture jets reasonably agree with those for the hot-air jet and the hot jet with afterburner under lean-burn condition with the error of 2 dB or less. Copyright © 2013 by the American Institute of Aeronautics and Astronautics, Inc.

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