30PY摇臂式喷头掺气与掺液的抽吸性能试验

Experiments on air and water suction capability of 30PY impact sprinkler

为了实现摇臂式喷头在较低的工作压力下工作,在原有结构基础上设置掺气管结构,形成水气两相射流开展喷灌作业.掺气管的吸气功能也可用于抽吸叶面肥液、药液,从而实现摇臂式喷头的多功能用途.为了掌握该结构的抽吸能力,选择掺气管的内径d,伸缩长度L以及摇臂式喷头喷嘴的收缩角度θ为影响因素,试验研究30PY摇臂式喷头掺气管堵住时形成的真空度以及抽吸水时的质量流量.结果表明:在相同喷头工作水压力下,喷头的喷嘴收缩角θ在30°~65°的试验范围内增大时,喷头的工作水流量减小,从而影响掺气或掺液时的混合比例;掺气管缩距离L相对喷嘴出口端面为0,当L从-4~6 mm移动时,掺气管的抽吸能力从0逐渐增大到最大,L取值2 mm为推荐值;掺气管内径d越大,摇臂式喷头的工作水压力越高,则掺气管抽吸流体的流量越大.

To allow an impact sprinkler to work in a low working pressure,an air admission structure can be installed coaxially in the water tube of sprinkler to form a water-air two-phase jet.The admitted air can make an impact sprinkler with a more uniform water distribution of irrigation.Further,the air admission pipe can convey liquid fertilizer or pesticide during irrigation,making the impact sprinkler multifunctional.In this paper,a series of experiments were carried out to investigate the capacity of an air admission structure for sucking both air and water into an impact sprinkler.The suction capacity was measured by water mass flow rate and vacuum degree.The structural parameters include inner diameter d,suction pipe engaging length L and nozzle convergent angle θ.All experimental work was conducted by employing 30PY impact sprinkler.When the nozzle convergent angle θ is increased from 30° to 65° under the same working pressure,the water flow rate reduces,and affects the two fluid mixing ratio in the sprinkler.The reference engaging length is zero,where the air admission pipe outlet jut meets the sprinkler nozzle outlet.When the suction pipe engaging length is varied in the range of-4 to 6 mm,the suction capability increases to the maximum from zero gradually and L = 2 mm is recommended because the suction capability is close to the maximum at this length.The sucked water flow rate increases with increasing sprinkler working pressure and inner diameter.Results of this study have formed a base for air admission impact sprinkler application in engineering.