Santrifüj nasoslar uchun kavitatsiya mavjud bo'lsa, u kundalik ish paytida tebranish va shovqinga olib kelishi mumkin, ba'zida biz ishlashni to'xtatishimiz kerak. Shunday qilib, biz markazdan qochma nasoslar uchun kavitatsiyaga qanday sabablar olib kelishini aniqlashimiz kerak, shunda biz bu savollarning juda aqlli ravishda paydo bo'lishidan qochishimiz mumkin.
The cavitation of centrifugal pumps, or the cavitation , is a process for flow liquid bubbles and then burst. When the absolute speed of flow liquid increase, as the static pressure of flow liquid decrease, for certain particle at a certain temperature of the fluid , although there is no heat from external input, but they have reached the vapor pressure, so that particle vaporization, and the bubble generated. Along the flow path.
Agar suyuqlikning statik bosimi yana bug 'bosimidan yuqori bo'lsa, qabariq juda tez yorilib ketadi. Kondensatsiya portlashi ta'sirining katta qismi. Agar qabariq suyuqlik oqimida emas, balki hidoyat yig'ish qismlarining devorida yorilib ketsa, kavitatsiya eroziyaga uchragan nam qismlarga olib keladi.
Santrifüj nasos kavitatsiya holatida ishlaganda, ho'l qismlar eroziyasi bo'lmasa ham, siz ayni paytda markazdan qochma nasosning shovqini juda katta ekanligini, tebranish kuchayishini, samaradorlikni pasaytirishini va shunga mos ravishda bosh juda past bo'lishini ko'rishingiz mumkin.
The equipment NPSHa , also called as effective NPSH. The equipment is provided by suction equipment, in the suction position of centrifugal pump, unit weight of the liquid have surplus energy more than vaporization pressure and head . Overseas call this an effective net positive suction head, That pump inlet (head position is zero) with a full head of liquid minus vaporization pressure and the net surplus value, represented by NPSHa. Its value and parameters related to liquid properties. Because inhalation device is proportional to the square of the flow and hydraulic loss. So NPSH decreases with the increase in capacity. NPSH-Q is a decreasing curve. The NPSH have relationship with the flow condition of pumps, it was balance pump inlet pressure drop decided by centrifugal pump itself. That is to say, in order to avoid the cavitation for the pump, we require that there is extra energy that could exceed vapor pressure head in the pump inlet. Overseas call this a required net positive suction head. The physical meaning of the pump NPSH indicates the degree of pump inlet pressure drop of the liquid. The so-called net positive suction head required, It is to require the inhalation device must be provided such a large net positive suction head, in order to compensate the pressure drops, to ensure that the pump cavitation does not occur.
Ko'p bosqichli santrifüj nasosning NPSH uskuna parametrlari bilan hech qanday aloqasi yo'q. Faqat nasos kirishidagi harakat parametrlari bilan bog'liq. Muayyan tezlikda harakat parametrlari va oqim parametrlari geometriya bilan belgilanadi. Ya'ni, NPSH nasosning o'zi tomonidan belgilanadi. Berilgan nasos uchun, suyuqlikdan qat'i nazar, ma'lum bir tezlikda va nasosning kirish qismidan oqib o'tadi, shuning uchun bir xil tezlik tufayli ular bir xil bosim tushishiga ega, bir xil NPSHr. Shunday qilib, NPSHr suyuqlik xususiyatlari bilan hech qanday aloqasi yo'q. NPSH kichikroq bo'lsa, bosim qanchalik kichik bo'lsa,
Ti uskunani kichikroq NPSHa bilan ta'minlashni talab qiladi, keyin esa nasos kavitatsiyasiga yaxshi qarshilik ko'rsatadi.
