Showing papers by "Japan Aerospace Exploration Agency published in 1997"

Surface pressure measurement in a cryogenic wind tunnel by using luminescent coating

Abstract: In recent experiments, we demonstrated the feasibility of using luminescent coatings for surface pressure measurement in a cryogenic wind tunnel. This technique is based on a new coating technology in which luminescent molecules are directly deposited onto the model surface by an electrochemical process. The resulting coating has an extremely high oxygen sensitivity for mole fractions of oxygen is less than 0.1%. This capability allows us to measure the pressure field on the model surface in a cryogenic wind tunnel. To demonstrate this technology, a 14%-thick bump model was tested in the 0.1-m Transonic Cryogenic Wind Tunnel at NAL. Mach number was changed from 0.4 to 0.84 whereas temperature was maintained at 100 K. A small amount of oxygen was injected into the tunnel and the mole fraction of oxygen in the test gas was kept constant. We acquired two intensity images, one taken at low speeds and the other taken at high Mach numbers. By taking the ratio of these images, surface pressure distributions on the model were clearly captured. The result of the in situ calibration showed that effects of temperature dependence of the coating was negligible. The paint-derived pressure distributions are in good agreement with pressure tap measurements.

Boundary-Layer Transition Detection in a Cryogenic Wind Tunnel Using Luminescent Paint

Abstract: Luminescent molecular probes imbedded in a polymer binder form a temperature or pressure paint. On excitation by light of the proper wavelength, the luminescence, which is quenched either thermally or by oxygen, is detected by a camera or photodetector. From the detected luminescent intensity, temperature and pressure can be determined. The basic photophysics, calibration, accuracy and time response of a luminescent paints is described followed by applications in low speed, transonic, supersonic and cryogenic wind tunnels and in rotating machinery.

Time series of physical and optical parameters off Shimane, Japan, during fall of 1993-First observation by moored optical buoy system for ADEOS data verification-

Abstract: 1National Institute for Resources and Environment, 16-3 Onogawa, Tsukuba, Ibaraki 305, Japan 2Japan Marine Science and Technology Center, 2-15 Natsushima-machi, Yokosuka, Kanagawa 237, Japan 3Faculty of Science, Tohoku University, Aoba, Aramaki, Sendai, Miyagi 980, Japan 4School of High-Technology for Human Welfare, Tokai University, 317 Nishino, Numazu, Shizuoka 410-03, Japan 5National Research Institute of Fisheries Science, 2-12-4 Fukuura, Kanazawa, Yokohama, Kanagawa 236, Japan 6The Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-01, Japan 7School of Marine Science and Technology, Tokai University, 3-20-1 Orido, Shimizu, Shizuoka 424, Japan 8Communication Research Laboratory, 893-1 Hirai, Kashima, Kashima, Ibaraki 314, Japan 9National Research Institute of Far Seas Fisheries, 5-7-1 Orido, Shimizu, Shizuoka 424, Japan 10Faculty of Fisheries, Hokkaido University, 3-1-1 Minato-machi, Hakodate, Hokkaido 041, Japan 11Japan Weather Association, 2-9-2 Kandanishiki, Chiyoda, Tokyo 101, Japan 12Remote Sensing Technology Center, 1401 Ohashi Numanoue, Hatoyama, Hiki, Saitama 350-03, Japan 13National Space Development Agency of Japan, 2-1-1 Sengen, Tsukuba, Ibaraki 305, Japan

ETS-VI On-Orbit System Identification Experiments.

Abstract: System identification and attitude control experiments have been performed as part of a series of bus experiments on the Engineering Test Satellite-VI, which was launched by an H-II rocket in August 1994. The aims of the experiments were to establish a pre-launch system dynamics modeling method, to evaluate typical on-orbit modal parameter identification methods and to develop robust and precise attitude controller design technology for future large flexible spacecraft and large space structures. In the on-orbit identification experiments, the central body of the satellite was excited by gas jet thrusters and the measured attitude and paddle accelerometer signals were downlinked by telemetry. In this paper, the identified parameters are compared with those of the pre-launch modeling and the accuracy of the pre-launch model is evaluated.

A study on supersonic mixing flowfield with swept ramp injectors

Abstract: In the present study supersonic mixing flows with parallel injectors are investigated experimentally and computationally. In the experiments the flow fields are visualized by the Schlieren method and flow technique. Also surface pressure distributions in the whole region are measured and complicated flow structure is revealed. In the present study three-dimensional full Navier-Stokes equations are solved for simulating threedimensional supersonic mixing flow problems in detail.The results show the present numerical code could capture the flow structure quantitatively to some extent. Also the results suggest the detailed and reliable experiments can be quite important in set for * Associate Professor, Senior Member, AIAA ** Research Scientists, Research Institute *** Graduate Students **** Research Scientist Copyright © 1997 by S. ASO, Y. YAMANE, K. UMII, K. TOKUNAGA, Y. ANDO and K. SAKATA. Published by The American Institute of Aeronautics and Astronautics, Inc., with permission. the code validation of numerical simulations.

Solution and Integrability of a Generalized Derivative Nonlinear Schrödinger Equation

Abstract: A generalized derivative nonlinear Schrodinger (GDNLS) equation \( {\rm i} U_t + {1\over 2} U_{xx} + |U|^2 U + {\rm i} \alpha |U|^2 U_x + {\rm i} \beta U^2 U_x^* = 0, \) is considered. Traveling wave solution is constructed for arbitrary values of parameters. Integrability of GDNLS equation is investigated by the Painleve test. Stability of the traveling wave solutions in interactions is examined numerically.

Thermoelastic Design of Symmetric Laminates Using Lamination Parameters

Abstract: An effective laminate design method is shown for thermoelastic properties of symmetric laminates with extension-shear or bending-twisting coupling. The relationship between thermoelastic properties and laminate configurations is examined by using lamination parameters which can express any laminate configuration. The coefficient of thermal expansion(CTE) is represented on the lamination parameter plane. The graphical representation clarifies the effect of laminate configurations on the CTE. It is shown that the CTE of graphite/epoxy composites can be controlled in a wide range from positive to negative values by tailoring laminate configurations. Thermal deformation characteristics of symmetrically laminated plates are also examined using lamination parameters for simply supported plates under two temperature conditions. An optimal laminate design of symmetrically laminated plates for thermal deformation is shown based on a mathematical programming method where four lamination parameters are used as design variables.

Visualization of the quiet test region in a supersonic wind tunnel using luminescent paint

Abstract: A temperature-sensitive luminescent paint technique has been used to visualize boundary-layer transition on a 10-degree cone model in the 0.2-m Supersonic Wind Tunnel at National Aerospace Laboratory. A luminescent paint based on EuTTA was applied on the model surface using airbrush. The paint coating was excited by a Xenon light and the luminescence image was acquired using a high resolution cooled-CCD camera. To enhance thermal signature across transition, tunnel flow was heated by a sudden shutdown of cooling water supply to heat exchanger. Two images were taken for each condition, one is transient image taken in heating process and the other is reference image taken in steady condition. By ratioing these two images, global transition patterns on the cone have been visualized as the edges of brightness. From transition images at various model locations in the test section, it was found that transition remains at a fixed spatial location with respect to the tunnel. This indicates that the cone transition is induced by radiated noise propagating from turbulent boundary layers on the tunnel walls. Effects of the stagnation pressure were also studied over the range from 55 to 150 kPa. The extent of quiet test region was found to be strongly sensitive to the pressure or unit Reynolds number. At the NAL 0.2-m SWT, natural transition did not occur on the cone at lower values of unit Reynolds number.

The influence of topography on wind over the Sea of Japan

Abstract: Wind is the critical factor in determining regional weather patterns and climate. Also, winds over the ocean directly effect the exchange of heat, moisture and gases between the atmosphere and the ocean surface. In this paper, the wind distribution over the Sea of Japan is analyzed by using wind data observed by the NASA Scatterometer (NSCAT). A synoptic view of the wind fields over the Sea of Japan is provided in January 1997. Remarkable evidence of a land topography effect is shown as a convergence of the surface wind field during cold-air outbreaks. The Changbai mountains are located in North Korea upstream of the outbreak winds, and the wind field was deformed by them over the western part of the Sea of Japan. Strong northwesterly winds (westerly winds) of about 16 to 20 m/s were observed off Vladivostok (the Korea Peninsula). They converge while blowing over the sea. A wind shadow, in which the wind speed is less than 8 m/s, is seen downwind of the mountains and extends more than 200 km. Numerical experiments using a three-dimensional local circulation model were performed to investigate the formation mechanisms of the outbreak-wind deformation. The results shows that the land topography is essential to form the convergence of the surface winds observed by NSCAT.

OCTS (Ocean Color and Temperature Scanner)

Abstract: Ocean Color and Temperature Scanner (OCTS) is a visible and infrared radiometer devoted to frequent global measurement of chlorophyll-a (Chl-a) and sea surface temperature. After a long break from global ocean-color observation, OCTS reopened its operations in November, 1996. An initial check of the sensor and preliminary results of cal/val have demonstrated the availability of the OCTS data for global ocean color research.