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金型鋳造では、鋳造条件によってさまざまな鋳物表面欠陥が発生する。対策として、金型に塗型を施していいる。しかし、塗型は多くの場合、経験と勘に基づいて行われている。本研究では、鋳造条件と塗型がAC4Cアルミニウム合金の流動性に及ぼす影響を調査した。その結果、鋳造温度と金型温度が高いほど、流動長が長くなることがわかった。また、塗型を施すことにより、流動長が大幅に長くなり、鋳物表面欠陥が減少した。溶融金属と金型との間の熱伝達係数を測定したところ、金型に塗型することで、熱伝達係数が約1/5に減少した。また、取得した熱伝達係数を用いてCAE解析を行ったところ、測定され流動長さと解析による流動長さが同程度であることが確認された。, In metal mold casting, various casting surface defects occur depending on the casting conditions. As a countermeasure, a coating is applied to the mold. However, coating is often done with experience and intuition. In this study, the effects of casting conditions and mold coating were investigated on the fluidity of AC4C aluminum alloy. As a result, it was found that the higher the casting temperature and the mold temperature, the longer the flow length. And that by applying the mold coating, the flow length becomes significantly longer and the casting surface defects were reduced. Also, the heat transfer coefficients between the molten metal and the metal mold were measured, the heat transfer coefficients ware reduced to about 1/5 by applying the coating mold. In addition, CAE analysis using the obtained heat transfer coefficient confirmed that the measured flow length and the analyzed flow length were almost the same.

The boiling heat transfer characteristics of binary mixtures; 1-Propanol/Water, 2-Propanol/Water and Water/Ethylene glycol mixtures, were investigated in pool boiling experiments under atmospheric pressure on ground to develop high-performance space thermal management systems. At extremely low concentrations of alcohol, increase in the heat transfer coefficients of 1-Propanol/Water and 2-Propanol/Water are confirmed while the critical heat flux values are decreased. Coexistence of the heat transfer enhancement due to Marangoni effect and the heat transfer deterioration due to mass transfer resistance is emphasized. The concept seems to be independent of gravity level., 資料番号: AA0063706051

Boiling heat transfer enhancement is efficient for development of a cold plate used in a two-phase flow loop type thermal control system. This study deals with boiling heat transfer enhancement for a narrow channel by thermal spray coating. Copper particles were coated on the heating surface by vacuum plasma spraying. Two kinds of surface were manufactured using different particle size, about 200 and 50 micrometer. The heat transfer performance was evaluated in saturated flow boiling experiments of HCFC123 for ranges of mass flux of 100 to 400 kg m(exp -2) s(exp -1), inlet quality of 0 to 0.60, and heat flux of 25 to 251 kW/sq m. The test channel with the channel width of 20 mm, and heated length of 100 mm was placed horizontally and heated from the bottom by cartridge heaters through a copper block. The channel gap was set to 2 and 4 mm. As the result, the coating surface produced higher heat transfer coefficient than the smooth surface, especially, the heat transfer performance of the surface using finer particle was higher and was about five to 10 times higher than that of the smooth surface. While the effect of gaps on the heat transfer coefficient was a little, the critical heat flux increased with increasing the channel gap., 資料番号: AA0063706054

In the present paper, results of force and heat flux measurement tests conducted in the JAXA 1.27 m Hypersonic Wind Tunnel (HWT) using the HB-2 standard model are presented. The tests were conducted at a nominal Mach number of 10, a stagnation enthalpy of 1 MJ/kg, and stagnation pressures from 1 to 6 MPa. Both for the force and heat tests, good data repeatability were confirmed. The heat transfer coefficient obtained from the IR thermography agreed well with the one from the thermocouple measurement. On the other hand, a conventional uncertainty estimation method which estimates the bias and random error components was applied to the force test data, whereas Monte Carlo approach was utilized to numerically estimate the uncertainty in the data reduction process of the heat flux data. The present experiment was conducted as a series of comparison test campaign between two hypersonic facilities in JAXA. The present test data is also expected to serve as a set of database for the validation of hypersonic computational fluid dynamics (CFD) codes., 資料番号: AA0049211008, レポート番号: JAXA-SP-05-016

航空宇宙技術研究所の大型極超音速風洞では、空力加熱測定を赤外線カメラを用いて行っている。この赤外線カメラによる空力加熱測定法は、従来の離散的なセンサによる測定法に比べ、機体全体にわたる空力加熱を2次元的な面情報として捉えられるため、局所的なピーク加熱も捕捉できる点で優れている。また、これまで定量測定精度の問題が指摘されていたが、誤差量の見積もり、補正方法の確立、3次元マッピングソフトウェアの開発、従来型のセンサとの比較試験などを行い、総合的な測定精度として10％以内の測定が可能であることを確認した。赤外線カメラによる空力加熱測定法は、極超音速風洞における空力加熱測定の実用的なシステムとしてほぼ確立した。ここでは、赤外線カメラによる空力加熱測定法の概要と定量測定精度を高めるために行った誤差の検討と補正法、センサとの比較試験などについて報告する。, 資料番号: AA0032235012, レポート番号: NAL SP-51

フィルム冷却層に外部から衝撃波が入射した場合の影響を調べるために、Mach数2.35の風洞を用いて超音速フィルム冷却の実験を行った。噴射器出口におけるフィルム冷却剤の噴射速度は音速とした。圧力比が1.21の比較的弱い衝撃波が入射した場合には、フィルム冷却の効果にほとんど影響は見られなかった。圧力比が1.44のより強い衝撃波が入射した場合には、局部的な領域でフィルム冷却の効果に低下が見られた。冷却剤流れと衝撃波が干渉する領域におけるこの冷却効率の低下は主として、冷却剤流れの局所Mach数の低下に伴って断熱壁温度が上昇するために起こることが分かった。この干渉領域においては、断熱壁温度と同様に、熱伝達係数の増加についても考慮する必要がある。また、干渉領域ではエネルギーおよび質量の輸送は促進されなかったが、主流側から冷却剤流側に対して運動量の輸送の促進が見られた。, Supersonic film cooling was tested in the Mach 2.35 wind tunnel to investigate the effect of the external shock wave on film cooling. The coolant was injected at sonic speed. The weak shock wave, whose pressure ratio was 1.21, did not reduce the film cooling effectiveness. The stronger shock wave, whose pressure ratio was 1.44, decreased the effectiveness of the film cooling in the restricted region. The decrease of the efficiency was mainly due to the increase of the adiabatic wall temperature by decreasing the local Mach number. The increase of the heat-transfer coefficient must be considered as well as that of the adiabatic wall temperature in the interacting region. In the region of the interaction, energy and mass were not transferred, but the momentum was transferred from the primary flow to the coolant., 資料番号: AA0000104000, レポート番号: NAL TR-1276

Recently, electric power demand goes on increasing. It is necessary to more electric substations and small cubicles. It is also wanted to compact gears and substations. This situation results in the narrow distance arrangement of the current buses and the handling of the high current and high temperature of the buses. Since the temperature rise of the bus is due to many heat transfer factors in the vicinity of the bus surface, it is analysed inclusively in this paper. From the engineering aspect, that is, the design aspect, it is important to know two fundamental values of heat transfer coefficiency and radiation efficiency necessary to decide the final temperature of the bus. The temperature are known from the method of phase plane of the nonlinear differential equation on the temperature rise including the radiation loss with their values. The calculated temperature is consisted with the experimental ones., 最近，電力需要が増加してきており，より多くの変電設備やキュービクルが必要である。これはまた，コンパクトな装置や変電設備を求めている。このような事情から，狭い間隔での電流母線の配置やこれら母線を大電流で，しかも高い温度で取り扱わなくてはならなくなってきている。母線の温度上昇はその表面周辺での多くの熱伝達因子によるが，この論文では，この温度上昇を総括的に解析した。工学的すなわち設計の立場から，母線の最終温度を決める基本的な2つの値，熱伝達係数と放射効率を知ることは重要である。この温度はこれらの値を用いて放射損失の項をもつ温度上昇に関する非線形微分方程式を位相平面の方法で知ることが出来る。この計算で求めた値と実験値とは一致を見た。

For the detail study on forced convective boiling heat transfer in mini- and micro-tube, we developed the transparent heated mini- and micro-tube by electroless deposition. The inner wall of the tube is coated with the thin gold film, which allows the visualization of fluid motion. At the same time, the film resistance derives the temperature measurement of the inner wall of the tube. As a result of forced convective boiling experiments by using the tube with 1 mm of inner diameter, it was found that the relation between behavior of boiling bubble and heat transfer coefficients were closely related, and existence of thin liquid film between the wall and slug, was very important for heat transfer enhancement., 資料番号: AA0063706052