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資料番号: PA1210030000

Numerical calculation based on large eddy simulation was carried out to investigate mixture formation process in a spray formed by injecting n-heptane into a constant volume vessel under high-temperature and high-pressure conditions. Liquid phase of fuel was described by discrete droplet model. The results show that the shape of spray is similar to that of visualized image and spray tip penetration corresponds well to experimental results. In addition, distributions of fuel concentration and local non-homogeneous distribution were discussed by comparing the calculation results with the mixture distributions measured using planer laser induced fluorescence technique. The local distributions were well described except around downstream spray boundary. Calculations were also carried out for lower injection pressure condition and smaller nozzle orifice diameter condition. Although fuel concentration in a spray does not quantitatively reproduce the experimental results, the effects of the injection conditions qualitatively agreed with the experiments. Furthermore, ignition and combustion processes were investigated using Schreiber's model for calculating the progress of oxidation reactions.

平成26年度衝撃波シンポジウム (2015年3月9日-11日. 群馬県伊香保温泉 ホテル天坊）渋川市, 群馬県, Symposium on Shock Waves in Japan, FY2014 (March 9-11, 2015. Hotel Tenbo), Shibukawa, Gunma, Japan, 資料番号: SA6000038122, レポート番号: P-16（若）

資料番号: AA0047118092

資料番号: AA0047118015

資料番号: AA0047118096

This paper proposes a new concept of a noise reduction nozzle and describes the sensitivity analysis of the nozzle's acoustic and thrust characteristics. The proposed concept envisages a variable nozzle that enables a change in cross-section and reduction of noise by a single mechanism. Under takeoff conditions, the nozzle has a convergent shape with teeth and slots similar to those of a spline hub, which enables noise reduction. On the other hand, under cruise conditions, the shape of the nozzle can be altered from convergent to a clean convergent-divergent configuration. This concept has been validated by scale model tests in a jet noise facility, and the sensitivity of the acoustic and thrust characteristics has been analyzed using numerical analysis. The analysis revealed that the acoustic benefit depends on the depth of slot, and its frequency characteristics depend on the number of slot. Thrust loss strongly depends on the nozzle throat position and weakly depends on the number of slot. The proposed concept has the potential to provide significant acoustic benefits relative to the thrust loss, and the results of the sensitivity analysis enable us to design appropriate nozzle geometry., 形態: 図版あり, Physical characteristics: Original contains illustrations, 資料番号: DS1740004002

20-21 May 1999 (62nd). 25-26 Nov. 1999 (63rd), 気流の圧力分布、総温度分布、および偏流角特性を測定するために、NALの大型極超音速風洞(マッハ数10)ではこれまでピトーレークとAGARD(航空宇宙研究開発顧問団)-J模型を用いて気流校正試験を行っている。1998年のM10ノズルの改修に先立ち、一連の気流校正試験の一環として、AGARD-E模型に関する詳細な圧力分布の測定を、付け加えて実施した。AGARD-E模型の試験部分の種々の位置での圧力分布を示す。実験値はニュートニアン、プラントル-マイヤー理論に比較して、やや小さな値を示した。, Flow calibration tests have been carried out using Pitot rake and AGARD (Advisory Group for Aerospace Research and Development) -J model at the NAL Large Hypersonic Wind Tunnel (Mach number 10) to measure pressure distribution, total temperature distribution and an angurality of the flow. As a series of flow calibration tests, pressure distributions on AGARD-E model additionally were measured in detail before modifying M10 nozzle in 1998. Pressure distributions on AGARD-E model are shown at various locations in the test section. The experimental values show relatively smaller in comparison with Newtonian, Prandtl-Meyer theory., 資料番号: AA0028634005, レポート番号: NAL SP-45

20-21 May 1999 (62nd). 25-26 Nov. 1999 (63rd), 航空宇宙研究所(NAL)が1995年に竣工した1.27m極超音速風洞はノズルを再加工することによって測定部気流の一様性を大幅に向上させることが出来た。CFD(計算流体力学)による評価法とスムージング法を用いトライアンドエラーによる手法によって圧力波を取り除くことに成功した。結果は次の通りである。(1)気流の非一様性は目標値を上回る平均マッハ数の±0.4%以内を達成することが出来た。(2)本流れの改善においてノズル再加工時の切削代とその分布を決定するのにトライアンドエラーによる手法を用いたが、その評価にはCFDが用いられ、高い信頼性と有用性を確認した。(3)ノズルの圧力波の発生を防止し、気流の一様性の向上を図るためには、加工時に寸法の精度だけではなく、壁面曲線の1次あるいは2次微分値の精度を厳しく管理することが重要であった。(4)吸込筒の位置の変化が気流の一様性に与える影響は小さった。気流の偏流角は目下測定中である。, The 1.27 m hypersonic wind tunnel was constructed at National Aerospace Laboratory (NAL) in 1995, and the uniformity of air flow at the measurement sites was improved to a great extent by re-machining the nozzle of the wind tunnel. Also, the pressure wave could be removed successfully by the evaluation method by CFD (Computational Fluid Dynamics) and by the trial and error method using the smoothing method. The results are as follows. (1) The non-uniformity of air flow was achieved to be within +/- 0.4 percent of the average Mach number, which was better than the target value. (2) To improve the main flow, the trial and error method was used to determine the cutting amount and distribution for the re-machining of the nozzle, and the evaluation was made by the CFD method, which was confirmed to have high reliability and usefulness. (3) It was very important to control strictly the accuracy of the first and second derivatives of the wall surface curve as well as the dimensional accuracy for the machining, in order to prevent the occurrence of pressure wave and to improve the uniformity of the air flow. (4) The influence of the jet catcher position on the uniformity of air flow was small. The drift angle of air flow is being measured at present., 資料番号: AA0028634011, レポート番号: NAL SP-45

The effects of spacing between dual jets on the heat transfer characteristics and flow behaviors over the plate surface were investigated experimentally when the dual slot jets impinge on the target plate. The local heat transfer distributions were measured for various spacings at small nozzle-to-plate separation distances and the flow pattern also visualized by the oil-titanium IV oxide method. An infrared radiometer with a two-dimensional array of InSb sensor was employed to clarify space varying in the flow and heat transfer accompanying by the interferences between jets, and jet and spent flow. The characteristics of heat transfer, flow patterns and thermal distributions change with the spacing of the dual jets and the nozzle-to-plate separation. The phenomenon of axes switching, which is caused by the differences in the self-induced velocity in the non-circular vortices, was observed farther downstream compared with that of a single impingement jet. These phenomena consequently played an important role in the heat transfer enhancement.

The experimental results on the abrasive water jet (AWJ) are described in this paper. AWJ is the high-speed water jet containing solid particles and is used for cutting of various industrial materials. In order to obtain the velocities of solid, gas and liquid phases at the mixing nozzle exit, the momentum of jet was measured. Phase velocity distribution in the axial direction of jet was also estimated based on the measured pressure distribution in the AWJ nozzle with the aid of the continuous and the momentum equations. The result shows that the decrease of the liquid phase velocity in the mixing nozzle is small in the case of the gas liquid two phase flow, and the velocity of liquid phase is remarkably reduced on the contrary in the gas liquid-solid three-phase flow. In the latter case, the total momentum of jet is reduced comparing with two phase flow. It is also found that the mean velocity of solid particles at the mixing nozzle exit is about 30% of the velocity of liquid phase.

This paper describes the hydrodynamic characteristics of the abrasive water jet (AWJ) flowing within smallbored nozzles. For analyzing high-speed water jet containing fine solid particles, we introduce the slip velocity model to the one-dimensional momentum equation and estimate the axial distribution of pressure and phase-velocities within the nozzle. The analytical result shows that (1) the pressure within nozzle is always in the vacuum side in case of high-speed water jet and (2) the pressure along the nozzle axis is greatly affected with the change in slip ratio. Experimental data using high-speed two speed two-phase flow of air-water mixture coincide with these predicted tendency. The data also show that there is steep pressure rise at the nozzle exit. From the data analysis, it is concluded that gas phase velocity exceeds its sonic velocity in some region within the nozzle and the phenomena like as normal shock wave may occur in the AWJ nozzle.

航空宇宙技術研究所 24-26 Jun. 1998 東京 日本, National Aerospace Laboratory 24-26 Jun. 1998 Tokyo Japan, 垂直板に入射する高温ジェットは地上からロケットを打ち上げる際に極めて重大な問題になることがある。これまで多くの研究が行われてきた。しかし、流れの機構は充分には明らかにされていない。本研究では垂直板に入射する超音波ジェットについて相互に作用する流れの場の数値計算を行う。ノズル出口と垂直板間の変位を変え、そして相互に作用する流れの場に及ぼす変位の影響を数値的に調査する。計算された流れのパターンと圧力分布は実験との良い一致を示した。, High temperature jet impinging on the wall sometimes become quite serious problems in launching the rocket from the ground. Several researches have been conducted by some authors. However, the flow mechanism has not been revealed sufficiently. The interacting flow fields of supersonic jet impinging on the wall are numerically simulated. The displacement between the nozzle exit and the wall is varied and the effects of the displacement on the interacting flow field are investigated numerically. The calculated flow patterns and pressure distributions show good agreements with experiments., 資料番号: AA0001958057, レポート番号: NAL SP-41

Heat transfer characteristics and flow patterns were measured over the plate for various separation distances between the nozzle exit and target plate when the air issuing from a sharpedged cross-shaped nozzle impinges on the plate. The local heat transfer coefficients in the radial direction for different circumferential positions were calculated using the wall temperatures measured by means of thermocouples, and the flow patterns were observed using a oil-titanium IV oxide method. The isotherms of the infrared images were also measured using an infrared radiometer with a two-dimensional array of InSb sensors. The geometric axes were switched due to the self-induced velocity of a vortex filament ; the convex corners became flat and the concave corners generated outward ejection. The distribution of the iso-heat-transfer-coefficient contours corresponds well to the flow pattern and the isotherm contours. These contours extended diagonally and demonstrated the Andrew's cross pattern for the short separations, subsequently becoming the octagonal patten, and then becoming circular at large separations. The correspondence of the heat transfer characteristic to the flow behaviors, and the heat transfer mechanism were also described.

In a previous study, the authors proposed slit injection as a jet noise suppressor for the Pre-cooled Turbojet Engine, and the noise reduction performance was examined experimentally. Using the slit injection, the noise radiation decreased. It was implied that, by using the slit injection, the instability of the jet was suppressed due to the deformation of the velocity profile of the jet. In this study, the effect of the deformation of the velocity profile of the jet by using the slit injection on the instability of the jet was investigated numerically. The velocity profiles were given by the results of a Pitot tube measurement. The stability of the jet was investigated using the linear stability analysis. The numerical results were compared with the jet noise spectra obtained experimentally. It was found that, by using the slit injection, the instability of the main jet oscillation mode, which may contribute to the noise radiation, was suppressed due to the mitigation of the steep velocity gradient of the main jet shear layer., 形態: 図版あり, Physical characteristics: Original contains illustrations, 資料番号: PA1520028000

The development of an air jet retrieval system of the gravel scattered on the road surface for the slip prevention is studied. The purpose of this study is to clarify the optimum installation condition of the jet nozzle for blowing the gravel. The height of the nozzle exit was h=5mm, and the width was 50mm. In changing blowing angle θ of the jet and standoff distance from the road surface yo, the blow off regions of the gravel were photographed and velocity distributions over the road surface were measured by hot-wire anemometer. As the result, optimum installation condition of the jet nozzle were found to be yo/h=2～3 and θ =15°～20°,where the blow off distance of gravel is increased., application/pdf

The gas-liquid mixing in the vicinity of the nozzle submerged in liquid to inject gases is an important process with respect to the commencement of chemical reactions and heat transfer in jets. The characteristics of the flow and the mixing were investigated concerning the super sonic jets of nitrogen injected into water through an orifice-type nozzle. The static and the total pressures, and the static and the stagnation temperatures in the jets were observed in the vicinity of the nozzle exit. In the case of the under-expansion discharge, the total pressure had an axisymmetric circular peak, similar to the radial profiles of those in the nitrogen-air super sonic jets. On the basis of the homogeneous two-phase flow model, some kinetic quantities were calculated using the pressures and the temperatures observed. The mass flux of water was evaluated to be highest in the peak region of the total pressure. It is probable that the gas-liquid mixing is most active in that region.

第1章 序論||第2章 モデルクロスフロー水車の設計||第3章 効率向上に向けた改善点の抽出||第4章 インナーガイドの効果||第5章 ガイドベーンの改良による効率向上の試み||第6章 実用化に向けた準備||第7章 結論, 九州工業大学博士学位論文 学位記番号:工博甲第361号 学位授与年月日:平成26年3月25日, 平成25年度