检索结果-南通市图书馆

Velocity and Size of Droplets in Dense Region of Diesel Fuel Spray on Transient Needle Opening Condition

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2005年第2期14卷 181-186页

作者： Hironobu UEKI Masahiro ISHIDA daisaku sakaguchi Nagasaki University 1-14 Bunkyo-machi Nagasaki 852-8521JapanNagasaki University 1-14 Bunkyo-machiNagasaki 852-8521JapanNagasaki University 1-14 Bunkyo-machiNagasaki 852-8521Japan

In order to investigate the effect of transient needle opening on early stage of spray behavior, simultaneous measurements of velocity and size of droplet were conducted by a newly developed laser 2-focus velocimeter (L2F). The micro-scale probe of the L2F was consisted of two foci with a distance of 36μm. The tested nozzle had a single hole with a diameter of 0.2 mm. The measurements of injection pressure, needle lift, and crank angle were synchronized with the spray measurement by the L2F at the position 10 mm downstream from the nozzle exit. It has been clearly shown that the velocity and size of droplet increase with needle valve opening and that the probability density distribution of droplet size can be fitted to the Nukiyama-Tanasawa distribution under the transient needle opening condition.

关键词：液滴分解光学特征激光2-聚焦速度计柴油机油料喷嘴

Global Search of a Three-dimensional Low Solidity Circular Cascade Diffuser for Centrifugal Blowers by Meta-model Assisted Optimization

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2018年第2期27卷 111-116页

作者： daisaku sakaguchi Daiki Sakue Min Thaw Tun Nagasaki University 1-14 Bunkyo-machi Nagasaki 852-8521 Japan Yangon Technological University Insein Road East Gyogone Insein Township Yangon

A three-dimensional blade of a low solidity circular cascade diffuser in centrifugal blowers is designed by means of a multi-point optimization technique. The optimization aims at improving static pressure coefficient at a design point and at a small flow rate condition. Moreover, a clear definition of secondary flow expressed by positive radial velocity at hub side is taken into consideration in constraints. The number of design parameters for three-dimensional blade reaches to 10 in this study, such as a radial gap, a radial chord length and mean camber angle distribution of the LSD blade with five control points, control point between hub and shroud with two design freedom. Optimization results show clear Pareto front and selected optimum design shows good improvement of pressure rise in diffuser at small flow rate conditions. It is found that three-dimensional blade has advantage to stabilize the secondary flow effect with improving pressure recovery of the low solidity circular cascade diffuser.

关键词：优化技术三维串联固态离心元模型搜索圆形

Noise Characteristics of Centrifugal Blower with Low Solidity Cascade Diffuser(Noise Reduction by means of Small Groove Located at LSD Blade Leading Tip)

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2009年第4期18卷 321-324页

作者： Tengen MURAKAMI Masahiro ISHIDA daisaku sakaguchi Yu KOBA Graduate School of Science and Technology Nagasaki University

This paper deals with the effect of the blade tip-groove of the low solidity cascade diffuser (LSD) on the blowercharacteristic and the noise generated by the LSD. The small grooves were set up at the root and/or tip near theleading edge of the LSD blade. In order to clarify the mechanism of noise increase due to LSD and also to reducethe noise, the relationships between the noise increase based on the LSD, the LSD performance and the secondaryflow formed additionally by the tip-groove were investigated experimentally as well as numerically, especiallyanalyzing flow behaviors in the LSD in view points of flow separation on the suction surface of the LSD bladeand the secondary flow on the side walls. By reducing the stagnation region smaller near the root and/or tip of theLSD blade leading edge, the secondary flow behavior changes remarkably around the LSD blade, as a result, thenoise level and the blower characteristics vary. It can be concluded that, by means of a small tip-groove locatedonly at the shroud side near the LSD blade leading edge, the noise generated by the LSD can be reduced withoutdeteriorations of the LSD performance and the blower characteristics as well.

关键词：叶片前缘离心风机级联低硬度降噪散光噪声性能恶化

Measurement of droplet size distribution in core region of high-speed spray by micro-probe L2F

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2008年第1期17卷 90-96页

作者： daisaku sakaguchi Oluwo le Amida Hironobu Ueki Masahiro Ishida Graduate School of Science and Technology Nagasaki University1-14 Bunkyo-machi Nagasaki 852-8521 JAPAN Faculty of Engineering Nagasaki University Professor

为了在柴油的核心区域调查微滴尺寸的分发，喷洒，微滴尺寸的即时测量被先进激光 2 焦点速度计(L2F ) 进行。L2F 的微规模的探查由二 foci 组成，在他们之间的距离是 36 μ m。测试的嘴有 0.2 公里直径单个洞。注射压力，针电梯，和曲... 详细信息

为了在柴油的核心区域调查微滴尺寸的分发，喷洒，微滴尺寸的即时测量被先进激光 2 焦点速度计(L2F ) 进行。L2F 的微规模的探查由二 foci 组成，在他们之间的距离是 36 μ m。测试的嘴有 0.2 公里直径单个洞。注射压力，针电梯，和曲柄角度的大小被 L2F 在位置与测量同步从嘴出口的 10 公里 downstream。比在在针下面的离开轴区域，完整的电梯调节并且微滴尺寸的空间分发改变速度集合，水花轴附近的微滴才大。在水花核心区域的微滴尺寸的概率密度分发能在大多数注射时期被适合到 Nukiyama-Tanasawa 分发，这被发现。

关键词：飞沫瓦解光学特征激光聚集速度计

Flow Range Enhancement by Secondary Flow Effect in Low Solidity Circular Cascade Diffusers

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2014年第4期23卷 391-400页

作者： daisaku sakaguchi Min Thaw Tun Kanata Mizokoshi Daiki Kishikawa Nagasaki Japan

High-pressure ratio and wide operating range are highly required for compressors and blowers. The technical issue of the design is achievement of suppression of flow separation at small flow rate without deteriorating the efficiency at design flow rate. A numerical simulation is very effective in design procedure, however, cost of the numerical simulation is generally high during the practical design process, and it is difficult to confirm the optimal design which is combined with many parameters. A multi-objective optimization technique is the idea that has been proposed for solving the problem in practical design process. In this study, a Low Solidity circular cascade Diffuser(LSD) in a centrifugal blower is successfully designed by means of multi-objective optimization technique. An optimization code with a meta-model assisted evolutionary algorithm is used with a commercial CFD code ANSYS-CFX. The optimization is aiming at improving the static pressure coefficient at design point and at low flow rate condition while constraining the slope of the lift coefficient curve. Moreover, a small tip clearance of the LSD blade was applied in order to activate and to stabilize the secondary flow effect at small flow rate condition. The optimized LSD blade has an extended operating range of 114 % towards smaller flow rate as compared to the baseline design without deteriorating the diffuser pressure recovery at design point. The diffuser pressure rise and operating flow range of the optimized LSD blade are experimentally verified by overall performance test. The detailed flow in the diffuser is also confirmed by means of a Particle Image Velocimeter. Secondary flow is clearly captured by PIV and it spreads to the whole area of LSD blade pitch. It is found that the optimized LSD blade shows good improvement of the blade loading in the whole operating range, while at small flow rate the flow separation on the LSD blade has been successfully suppressed by the secondary flow effect.

关键词：二次流动流量范围扩散器密实度多目标优化叶片扩压器设计流量粒子图像测速仪

Control of Secondary Flow in a Low Solidity Circular Cascade Diffuser

在线全文

学校读者我要写书评

暂无评论

Journal of Thermal Science 2012年第4期21卷 384-390页

作者： daisaku sakaguchi Takuji Fujii Hironobu Ueki Masahiro Ishida Hiroshi Hayami Nagasaki University 1-14 Bunkyo-machi Kyushu University (retired)

According to the previous experimental works on the low solidity circular cascade diffuser (LSD), a pressure recovery of a centrifugal blower was improved by the LSD significantly in a wide range of flow rate, and the pres-sure recovery was improved further by the LSD with a tandem cascade in comparison with the LSD with a sin-gle-row cascade. In the present study, the flow behavior in the LSD with the tandem cascade has been analyzed numerically by using the commercial CFD code of ANSYS-CFX12. It was shown clearly that the higher pressure recovery was achieved by applying the LSD with the tandem cascade, and the high pressure recovery is based on the high pressure rise in the vaneless space upstream of the LSD and the high blade loading of the front blade of the LSD. The high pressure recovery in the LSD could be achieved by controlling the flow separation on the suc-tion surface of the front blade and also on that of the rear blade due to formation of the favorable secondary flow and due to increase in mass flow passing through the slit section between the front and rear blades.

关键词：控制梯级循环二次流扩散器压力恢复离心式鼓风机质量流量