For the purpose of the design of noncircular , square having different inside contracting angles, and triangular having different inside contracting angles and height-to-width ratios were tested. Water distribution profiles and the largest droplet diameters for square , and water distribution profiles for triangular were established. For a square nozzle, it was found that the effect of the inside contracting angle on the discharge coefficient, pattern radius, and water distribution profile is significant when the angle exceeds 50°. The suitable inside contracting angle turns around 30°. For a triangular nozzle, the influence of the inside contracting angle on its water distribution is insignificant when the angle ranges from 10° to 45°. Water distribution profiles are sensitive to the height-to-width ratio of the triangular orifice. A 1.00 height-towidth ratio nozzle usually gives higher uniformity coefficient than the other ratio at low pressure.

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The effects of nozzle geometry on cavitation in the nozzle of pressure atomizers and the liquid jet are examined using various two-dimensional (2D) with different geometries. Then, whether or not the conventional cavitation numbers can be used to predict the formation of supercavitation, in which liquid jet atomization is enhanced, is examined. As a result, we confirm that (1) the thickness of the cavitation zone increases with the ratio C_u of the cross-sectional area upstream of the nozzle to that of the nozzle, (2) the spray angle increases with C_u, (3) the formation of supercavitation can be predicted using the cavitation number σ_c' in which the effects of the flow contraction and the frictional pressure drop are taken into account, and (4) the conventional cavitation numbers σ, σ₂ and σ₃ cannot predict the formation of supercavitation in with different geometries.

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In the present paper, parametric numerical analyses of the separated transonic flows in overexpanded rocket are conducted. Several types of are examined numerically to clarify the detailed mechanisms of the occurrence of restricted shock separation (RSS) in compressed truncated perfect (CTP) . The effects of nozzle length and geometric compression factor are examined. In CTP with large length and small compression factor, a positive pressure gradient appears downstream of the Mach disk before the occurrence of RSS. Under the positive pressure gradient, the flow, which passed through the Mach disk, rolls up and forms a large vortex ring around the nozzle exit. The vortex ring pushes the separated jet towards the nozzle wall and results in RSS.

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For a double rectangular nozzle, the inside contracting angle, length-to-width ratio of the rectangular slot, and spacing between two rectangular slots are its main three design parameters. Water distribution profiles and droplet diameters for having different design parameters were tested. It was found that water distribution and droplet diameter are highly sensitive to both the spacing between two rectangular slots and the length-to-width ratio of the slot; however, the hydraulic performance of a double rectangular nozzle appears to be independent of the inside contracting angle. The effect of the diffuse extent of jets formed by double rectangular on the sprinkler rotation speed was also investigated, and it was found that the speed decreases as the diffuse extent of the jet increases, and either a large slot spacing or a small length-to-width ratio may lead to a low rotation speed.

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工業用ボイラーには種々のノズルが用いられている.炭化水素燃料使用による環境への配慮は, 定格出力に対する燃焼量が少ないほど二酸化炭素の削減につながる.ノズルの使用にあたっては, 出力を1次圧力の変化無しに制御できる比例制御ノズル1本の場合や油圧制御ノズルを2, 3本装着し, 油圧により流量を制御する場合等がある.比例制御ノズルは主配管とバイパスとなる管を持ち, バイパスラインを通る流量をバルブにより線形に制御する事が出来る.油圧制御ノズルは1次圧力を調整する事によって, 流量を制御している.1本ノズルの比例制御及び2本ノズルの油圧 (段位) 制御の燃焼実験による排気ガス測定結果によると, 比例制御によって排出される窒素酸化物の値は, 油圧 (段位) 制御のものに比べて約20%低い値になっている.その原因は噴霧の重なりによるものなのか, 噴霧特性の差異によるものなのかは, 把握されていない.本研究には出力を等しいと仮定できる比例・油圧制御ノズル単体の噴霧粒子をPDPAを用い, 噴霧粒子の速度, 粒子径並びに数密度を測定し, 噴霧特性の観点から問題解明を目標とした.さらに, 実験に使用した比例制御ノズルの構造の違いによる差異の測定も行った.構造上の違いはバイパスラインへの戻り口 (穴) の径及び数の違いである.実験結果により, 比例制御ノズルの戻り穴の形状は噴霧特性に顕著な影響を及ぼしてはいない.油圧制御ノズルによる流量変化には粒子径変化が伴うが, 比例制御ノズルでの流量変化に対する粒子径の変化は確認できなかった.

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A mechanism for the local corrosion of immersion at the slag–metal interface was quantitatively substantiated by combining results from kinematic analysis of immersion tests with direct observations using a high temperature X-ray radiographic technique.
For steels containing low carbon levels (e.g., steel for continuous casting), the dissolution of oxides from the nozzle into the slag film is the rate controlling step of the local corrosion process. For steels contaning higher carbon levels (e.g., in the vicinity of carbon saturation), dissolution of graphite from the nozzle into the metal is rate controlling.
It was found that if the nozzle:
(i) has a high resistance to corrosion by liquid slags; and
(ii) is easily wetted by the slag.
Then it will exhibit a good resistance to local corrosion at the slag–metal interface.

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A newly developed bottom gas blowing method consisted of bottom nozzle with double or triple annular tubes was presented to improve the flexibility of the bottom gas flow rate and the bottom blowing stability. Hydrocarbon blowing through the inner tube of the bottom nozzle realized stable stirring without over cooling of the nozzle. By using bottom gas blowing method mentioned above, iron oxidation was suppressed in the last stage of the blowing and (T.Fe) content which meant iron content existed as iron oxide in the slag was decreased.

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Fuel injection pressure of diesel engines has been increased to improve engine performance and to reduce emission year by year. The higher injection pressure causes a cavitation and leads to erosion in the nozzle hole. Deformation of nozzle hole may result deterioration in engine performance, especially when using heavy fuel oil. It is noted that rounding-offof nozzle hole inlet proves to be effective to maintain the nozzle hole shape and the injection characteristics. In the present paper, from a fundamental viewpoint, measurement of ignition delays of diesel sprays from single hole injection with and without rounding-off hole inlet were conducted in a high-pressure combustion chamber. Further, fuel flow patterns in the nozzle hole were numerically simulated by three dimensional highly precision nozzle flow model.
When ambient pressure and fuel injection quantity are relatively low, sprays from nozzle without rounding-off hole inlet do not ignite at low ambient temperature. On the other hand, there is no difference in ignition delay under high ambient temperature. In cases where an ambient pressure is high enough and a large amount of fuel is injected, ignition delays of nozzle with rounding-off and without rounding-off show almost the same values even at low ambient temperature. The computed results of numerical simulations show that cavitation level decreases significantly for all cases of rounding-off .

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In a top-blowing converter, when a distance between the top-blowing lance and the molten metal surface increases, post-combustion ratio increases, but its heat transfer efficiency to the molten metal decreases. Therefore, a fundamental study of a gas jet behavior from the lance

was carried out in order to develop a new oxygen top-blowing lance with side with the aim of achieving both higher post-combustion ratio and higher heat supply to the molten metal in converter.

In order to design the shape of the side

and blowing conditions, cold model experiments and numerical calculations were carried out to investigate the effect of the inclination angle of the side and the flow rate on the gas jet behavior of the . It was found that the gas jet from the side was deflected to the direction away from the side wall of the lance due to a difference in the pressure distribution at the nozzle outlet. The deflection angle can be estimated by an equation using the supply pressure, atmospheric pressure and inclination angle of the nozzle.

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The purpose of this study is to search for a new method of dispersing spilled heavy oil, which has a detrimental effect on the natural environment and marine ecosystem. A method ejecting a waterjet vertically downward to heavy oil on the water surface was studied, particularly focusing on the effect of the guide nozzle shape. The waterjet comprised heavy oil and minute air bubbles, and passed through the hole of the guide nozzle. Thirteen guide nozzle shapes were tested and compared. The dispersion efficiency of a tapered hole was the best among the 13 . The flow in the hole of the guide was recorded by a high-speed video camera. The occurrence of two flows, regular and counter flows, was observed in the taper guide nozzle. It seemed that the counter flows generated the shearing force between the waterjet and the heavy oil layer. It is considered that the shearing force determines the surplus efficiency of disperse.

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燃料噴射ノズル内の流量特性は、噴口入口形状に影響され、燃料噴霧と燃料・空気混合気の形成過程に強く影響を及ぼす。一方、燃料噴射圧は、機関性能の向上と、排出微粒子を低減するためにますます高くなっている。しかしながら、噴射圧の上昇は、ノズル噴口部周辺に、より高い応力とキャビテーションを発生させる。そしてこれらの要因によって噴射ノズルの内部形状を変形させることになる。
この研究の主眼は、噴射ノズルの入口形状が燃料噴霧特性に及ぼす影響を数値解析及び実験的に調べることである。この目的のためにR取り有り・無し噴射ノズルを製作した。また、2相流と噴霧の数値解析のために弁リフトと噴射量及び実燃料噴射圧をインプット圧力として、計算条件に取り込んだ。そして、高速ビデオカメラを用いて、噴射ノズルの入口形状 (噴口部のR取りの有無) による燃料噴霧角に及ぼす影響を調べた。その結果、 (1) 同一燃料噴射量において、燃料噴射圧力36MPaのときにR取り有りノズルの噴霧角はR取り無しノズルのそれより8～14度大きくなった。
(2) 数値解析の結果、R取り半径を大きく取ると、無次元r=R/D (R: R取り半径、D: ノズル噴口径) =0.5までは、質量流量は直線的に増加 (約40%まで) するが、r=0.5～1.25では増加率がほぼ一定になることなどが判った。 (3) 燃料噴霧角は雰囲気圧の影響を大きく受けるとともに噴射後の噴霧角は実験値が数値解析値より少し大きくなったがその両者の傾向は、よく一致した。
これらの結果から複雑な燃料噴霧の特性を調べるためには、実験結果に加えて数値解析手法を用いることが重要である.

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Despite every means available at the time of construction applied to prevent vibration, violent vibrations were reported on two ocean-going tugboats constructed by IHI, of size that places them among the world's largest. Measurements made of the vibration of aft part including and analysis of measured data revealed that the vibrations of : -
-were constant in frequency, irrespective of propeller or engine revolution, and attained values of acceleration reaching 8, 000 Gal;
-were generated only under certain conditions of operation, and diminished to very low levels under all other conditions ;
-corresponded to what is known as flow-induced vibration, and were closely associated with the water flow around the .
Two possibly ascribable mechanisms were considered as cause of the self-excited vibration.
(1) Locked-in vibration induced by Karman's vortex street ;
(2) Occurrence of negative damping (known as “galloping”).
Neither of these two mechanisms have so far proved conclusively assignable as cause : (1) Karman's vortex streets on account of uncertainty in estimating the exciting force under lock-in condition, and (2) galloping for lack of definite tendency of the negative slope of nozzle lift vs. attack angle curve.
The vibrations observed being of such amplitude as to permit no delay in remedial action, measures were taken to counteract both the mechanisms considered above : (1) Karman's vortex streets by attaching fins to the to decrease their trailing edge thickness, and hence to modify the shedding frequency of the vortex streets, and avoid resonance ; (2) galloping by strutting the two together so as to constrain them to in-phase vibration mode, which was considered from observation of the damping behavior to be conductive to marked modification of the structural and mass damping performance, and consequently convert the damping to positive value.
Vibration measurements reperformed after applying the above measures proved. the violent vibrations to have been completely eliminated, evidencing ample effec tiveness of the measures adopted. Further token of the effectiveness of the measures is provided by the complete absence of reports from either tugboat on violent vibrations, throughout the two years that have since elapsed, during which the tugboats have each marked over 4, 000 hours of active service.

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We aimed to develop a new powder metallurgy process to produce next generation common rail diesel

with tiny and complexly shaped holes. High-speed centrifugal compaction and powder metallurgy were used. Three nozzle samples with holes of straight and tapered (8°, 16°, enlarged inwardly) were made. Three samples without external and inner defects were examined by spray test, which was performed with an ambient pressure of 1 and 4 MPa, an injection pressure of 150 MPa, and was studied by filming using a high-speed camera at 8000 fps. The measuring parameters were the penetration, spray angle, and spray cone angle from the spray aperture. As the taper angle increased, the penetration and spray cone angle increased.

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We have developed a new type of hose nozzle, which uses either water or compressed air foam (CAF), as a more efficient fire-fighting strategy. In this paper, a description of the measured spray range and foam expansion of both the prototype nozzle and conventional

is given. The results show that the spray range of the prototype nozzle is equal or superior to that of conventional . The foam expansion capability of the prototype nozzle is far superior to that of existing . From these results, it was confirmed that the new type of hose nozzle suggested in this paper will be an effective addition to existing firefighting equipment, resulting in a more efficient firefighting strategy.

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We began development of swirling-flow submerged entry in 1997 as a fundamental and effective measure for controlling the flow pattern in continuous casting molds. As a first step, we developed a swirling-flow submerged entry nozzle for round billet casting at the Wakayama works. We then began developing swirling-flow submerged entry for slab casting. The main purpose of the present work was to demonstrate that the formation of swirling flow in submerged entry nozzle improves productivity and the quality of products in continuous casting. We examined swirling-flow submerged entry with a swirl blade in these main bodies because such an arrangement is the easiest way to apply swirling flow to submerged entry in continuous casters without investment by facilities. We had only to change the submerged entry nozzle in the experiment. Swirling-flow submerged entry for slab casting were developed and their operation examined at the Wakayama and Kashima works. It was found that the proposed submerged entry increased the casting speed and improved the surface quality of slabs and steel sheets.

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Bubble formation from a centered single-hole nozzle placed on the bottom of a water bath has been investigated using a high-speed video camera. Wetted and poorly wetted are used to understand the effect of wettability of nozzle on the bubble formation in the water. When the gas flow rate is lower than a certain critical value, the frequency of bubble formation is specified by the outer nozzle diameter. On the other hand, when the gas flow rate is raised above another critical value, the inner nozzle diameter governs the bubble formation. An empirical equation is proposed for the frequency of bubble formation in the water.

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A direct heat exchange system using zeolite 13X–water working pairs is expected as an effective process to generate steam more than 150°C from water below 100°C. As a basic study, steam at 100°C from water at 80°C was investigated. The effects of the direction of feeding water in the adsorption process were experimentally investigated. The experimental results for the feeding from the bottom show that mass of generated steam reached almost 90% of the theoretical value obtained by heat mass balances. However, the performance, that is, the mass ratio of generated steam to the inlet water was around 6.5% because an abundance of water should be introduced to get contact between zeolite particle and water. Feeding water from the top was, therefore, investigated to increase the performance of steam generation with various nozzle configurations. Although the mass of the product steam was less than that for feeding water from the bottom, the mass ratio was improved to 13% by using 14 . This is because the nozzle installation enlarged the contact area between water and zeolite with a small amount of water.

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Cavitation in a cylindrical nozzle and liquid jets discharged from the nozzle are simultaneously visualized using a high-speed camera to investigate the mechanism of liquid jet atomization induced by the fully-developed cavitation. Three mirrors are used to capture the front view of liquid jet interfaces and the side view of cavitation clouds within a frame of the camera. The high-speed visualization confirms that the collapse of a cavitation cloud near the nozzle exit induces a ligament formation not only for 2D but also for cylindrical . The visualization also finds that the collapse of a large cavitation cloud tends to cause the formation of a large ligament, while that of a small cloud results in a small ligament.

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The jet flow phenomena are not only interesting but also important in the field of fluid and thermo dynamics and engineering. Moreover, they are used widely in various kinds of industries, for example, for mixing-, diffusing-, heating-, cooling-, and transporting-processes. The flow characteristics of jet flows are influenced considerably by the nozzle geometry. The mean and fluctuating velocity profiles at the nozzle exit are quite different by the nozzle geometry, and these affect largely on the jet flow characteristics in the downstream. In this paper, the effects of the nozzle geometry on the jet flow characteristics, especially mixing-, spreading-, diffusing-, and heat-transfercharacteristics for the pipe-, orifice-, notched orifice-, petal shaped-, and others- are discussed, and their some applications are shown.

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Bubble columns with constant-flow were used to obtain high values of gas holdup ε and volumetric mass transfer coefficient k_La for highly viscous liquids at relatively low gas-flow rates.
Effects of various factors on ε, k_La, mass transfer coefficient k_L, bubble volume V_B formed at constant-flow nozzle, and gas–liquid interfacial area a were investigated experimentally. Liquid viscosity, superficial gas velocity, number of constant-flow and pitch affected ε, k_La, k_L, V_B and a. The experimental results were correlated by dimensionless equations, which were compared with previous works.
For a given energy input, a in this bubble column was larger than that in conventional bubble columns with a perforated plate as gas distributor.

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