著者

奥山 圭一 加藤 純郎 山田 哲哉

出版者

宇宙航空研究開発機構

雑誌

宇宙航空研究開発機構研究開発報告 (ISSN:13491113)

巻号頁・発行日

vol.4, pp.55-75, 2005-03

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REV was the first reentry capsule developed through pure domestic technology and successfully recovered. REV is thermally protected against the severe aerodynamic heating by carbon-phenolic ablator material. The present paper describes the feature of the heating test in the arc windtunnel and the ablator characteristics clarified during the research and development process of the REV heatshield. Because the heat flux anticipated on the stagnation surface is about 2 MW/m^2, the dominant surface recession mechanism is identified to be in the reaction control region. The thermochemical reaction data have been acquired through three arc-heater facilities with different enthalpy level for calibration and tuning of the ablation analysis code. The thermomechanical behavior of the ablator under the high heat flux environment such as delamination, or spallation also has been investigated for functional safety of the heatshield.

著者

松田 昇一 加藤 純郎 秋葉 貴光

出版者

一般社団法人 日本機械学会

雑誌

年次大会 2020 (ISSN:24242667)

巻号頁・発行日

pp.S05406, 2020 (Released:2021-03-25)

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Impingement jets are often used for cooling and heating of a surface or a body because a high heat transfer coefficient is obtained near the stagnation point of an impingement surface. For example, they are used for drying paper and fabrics, cooling gas turbine blades and electronic components(1). Recently, the usage of impingement jets can be predicted to be used in comparatively small spaces due to the miniaturization of devices. In these cases, the nozzle diameter, the flow rate, and the distance between the nozzle and the impingement plate are inevitably small.The purpose of this study is to clarify the flow and heat transfer characteristics when an impingement jet is applied in a narrow space. And now, when the heat transfer coefficients are measured by using the thin heated surface, a heat loss (qe) occurs in the in-plane direction of the heated surface due to heat conduction. Generally, this heat loss is often ignored at high Reynolds number (Re) and large diameter, because it is very small compared to the heat taken by the impingement jet. However, it may not be negligible in the case of a low Reynolds number and small diameter, because the heat taken by the impingement jet become relatively small.In this research, heat transfer characteristics using a circular impinging jet, which impinge on the heated plate, were investigated experimentally. The jet holes with the diameters D of 1, 3 and 5 mm were used. The values of H/D were from 2 to 6, where H is the distance between the nozzle exit and the impingement plate. The experiments were performed with the relatively low Reynolds number range of 250 ~ 2500. The surface temperature of the impingement plate was measured using an infrared camera, from which a heat loss (qe) in the in-plane direction and heat transfer coefficients were obtained. And the flow behavior of the jet was visualized by using a Laser Light Sheet(LLS)method. From the experiments, it was found that a heat loss (qe) needs to be considered in the case of a low Reynolds number and a small diameter.

著者

米須 清一郎 松田 昇一 加藤 純郎

出版者

一般社団法人 日本機械学会

雑誌

年次大会

巻号頁・発行日

vol.2017, 2017

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<p>Impingement jets are often used for the cooling and heating of a surface or a body because a high heat transfer coefficient is obtained near the stagnation point of an impingement surface. Recently, as equipment becomes smaller, impingement jets have been utilized in narrow spaces. In such a case, the nozzle diameters and Reynolds number which based on the nozzle exit velocity also become tinier as a matter of course. Generally, in the case of measuring the heat transfer coefficient by using a thin heat transfer surface, heat loss, <i>q</i>_e due to heat conduction in the in-plane direction in the heating surface occurs. However, <i>q</i>_e has been considered inconsequential in the case of the common impinging jets having large diameters and with large Reynolds number. However, <i>q</i>_e may not be negligible in the case of impinging jets having a small diameter and with low Reynolds number. In this research, heat transfer characteristics using rows of impinging jets with small diameters and with low Reynolds number were investigated experimentally. The jet holes with the diameters <i>D</i> of 1, 2 and 3 mm were used. The experiments were performed with the relatively low Reynolds number range of 170~1460. The surface temperature of the impingement plate was measured using an infrared camera, from which heat transfer coefficients on the surface were obtained. It was found that the <i>q</i>_e needs to be considered in the case of impinging jets having small diameters and with low Reynolds number.</p>