Flushing Phenomenon of Fine power

精电冲水现象

• 批准号: 13650185
• 负责人: TOMIYAMA Yuji
• 金额: $ 2.3万
• 依托单位: Kyushu Institute of Technology
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2001
• 资助国家: 日本
• 起止时间: 2001 至 2002
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-13650185/
• 关键词: Flushing; Fine Power; Adhesion Property; Powder Head; Air Pressure; Flooding; Voidage; Handling; 液状化; 付着力; 衝撃力; 粉体圧

Generally, fine power cannot flow out through a small orifice or narrow channel due the cohesiveness. However, if the power contains air, unexpected fluidization occurs and the power flows out of the orifice or channel like a liquid. We call this a flushing phenomenon, which becomes a possible source of troubles in handling of power in industry. We have explained a mechanism of flushing phenomenon as follows; when the air pressure in the void of power is increased by some external stimulus, the pressure difference is produced between the power and the outside, which, in turn, produces air flow from power to the outside through a small orifice or narrow channel and the power is spouting entrained by the air flow. Kuchii et al. increases the air pressure of power in a cylinder by applying a piston load on the free surface and Okamura et al. produces a periodical air pressure by applying vertical vibration on the power bed. However, the flushing phenomenon in practice is produced by the different means.In this work, we generated air pressure in power in a cylindrical vessel by the impact of falling aerated power on the surface, and at the same time a high voidage power bed was created. Then the flushing phenomenon was produced through the bottom orifice. Furthermore, we found that the power bed of higher voidage can keep the flushing by the weight of the powder bed. We generated the flushing by fluidizing the power bed introducing air from the vessel bottom for a given voidage and then opening the bottom orifice as well as stopping the aeration. By this method we can consider the flushing avoiding the complicated phenomenon involved by the power impact. We found out the effects of air pressure, voidage, bed height and orifice diameter on the flushing phenomenon.

通常，由于内聚性，细粉末不能通过小孔或狭窄通道流出。但是，如果粉末中含有空气，则会发生意想不到的流化，并且粉末会像液体一样流出孔或通道。我们称之为冲洗现象，这可能成为工业中处理电力的麻烦之源。我们已经解释了冲洗现象的机理如下：当动力空隙中的空气压力由于某种外部刺激而增加时，动力与外部之间产生压力差，这反过来又产生空气流，从动力通过小孔或狭窄的通道流向外部，动力被空气流夹带着喷出。Kuchii等人通过在自由表面上施加活塞载荷来增加气缸中的动力气压，Okamura等人通过在动力床上施加垂直振动来产生周期性气压。但实际中的冲粉现象是通过不同的方式产生的，本工作利用充气粉落在容器表面的冲击力，在圆筒形容器内产生粉内气压，同时形成高空隙率的粉床。然后通过底部孔口产生冲洗现象。此外，我们还发现，空隙率较高的粉末床可以通过粉末床的重量来保持冲洗。我们通过流化动力床产生冲洗，从容器底部引入空气达到给定的空隙率，然后打开底部孔口并停止曝气。通过这种方法，我们可以考虑冲洗，避免了复杂的现象所涉及的功率冲击。研究了空气压力、空隙率、床层高度和喷孔直径对冲刷现象的影响。

项目成果

若水 洋, 藤川幸治, 船津勝也, 富田侑嗣: "気中雰囲気における微粉末の連続フラッシング現象の研究"第56期総会講演会日本機械学会九州支部講演論文集. No.038-1. 107-108 (2003)

Hiroshi Wakamizu、Koji Fujikawa、Katsuya Funatsu、Yuji Tomita：“空气气氛中细粉的连续冲刷现象的研究”日本机械工程学会九州分会第 56 届大会论文集第 038-1 号。 - 108 (2003)

若水 洋: "気中雰囲気における微粉末の連続フラッシング現象の研究"第56期総会講演会日本機械学会九州支部講演論文集. No.038-1. 107-108 (2003)

若水浩：《大气中细粉的连续冲刷现象的研究》第56届日本机械工程学会九州分会会议记录第038-108号（2003年）。