Improving the suction performance of centrifugal pumps by using jetting device is presented. The theoretical analysis, experimental study and engineering implementation show that suction performance of centrifugal pum...Improving the suction performance of centrifugal pumps by using jetting device is presented. The theoretical analysis, experimental study and engineering implementation show that suction performance of centrifugal pump can be improved with jetting device and be used for delivering the liquid media requiring high suction performance, whereas the efficiency and head of the pump will decrease a little. The effect of feed-back jetting on suction performance is the most obvious at design point. The suitable rate of feed-back flow is 2%-5%.展开更多
Due to the maize growing agronomy requires ground covered by mulch film in the arid zones of the China Northwest region,the seed-metering device must roll over,break the film,and then throw seeds into soil.However,the...Due to the maize growing agronomy requires ground covered by mulch film in the arid zones of the China Northwest region,the seed-metering device must roll over,break the film,and then throw seeds into soil.However,the uneven ground can cause the seed-metering device to shake,reducing seed-metering performance.To improve the adaptability for different shapes of maize seeds,a air suction wheel type seed-metering device with elastic pad was developed for better seed extraction and bump resistance.Firstly,the advantages and influencing factors of the elastic pad were analyzed through four processes of metering seeds.Secondly,the velocity distributions of six diameters of the suction hole are compared to determine the range with FLUENT.Then,a one-factor experiment was conducted to analyze the pattern of the factors(the seed layer height,the critical vacuum,the rotational speed of the seed disk,and the suction hole diameter)influencing the metering seed performance.Finally,a five-level quadratic rotation orthogonal design was used to optimize the parameters.Results show that the optimal values are that the seed layer height is 40 mm,and the critical vacuum is 2.85 kPa,and the rotational speed of the seed disk is 20.1 r/min.The validation experiment resulted in a 93.79%qualified index,with a 4.02%missing index and a 2.19%multiple index.展开更多
目的探讨Kiwi胎头真空吸引器在阴道助产分娩中的应用价值。方法选取2020年7月至2023年3月于扬州大学临床医学院使用Kiwi胎头真空吸引器实施胎头吸引的初产孕妇30例为胎吸组,同时选取计划阴道分娩而后因特殊原因行剖宫产终止妊娠的孕妇2...目的探讨Kiwi胎头真空吸引器在阴道助产分娩中的应用价值。方法选取2020年7月至2023年3月于扬州大学临床医学院使用Kiwi胎头真空吸引器实施胎头吸引的初产孕妇30例为胎吸组,同时选取计划阴道分娩而后因特殊原因行剖宫产终止妊娠的孕妇23例为剖宫产组。比较2组术中及术后情况及新生儿相关指标。结果2组第二产程时间、产时出血量、产后24 h出血量、产后住院时间及软产道损伤、产后会阴水肿发生情况比较,差异无统计学意义(P>0.05)。2组产后尿潴留发生率比较,差异有统计学意义(P<0.05)。2组新生儿出生体重及头皮血肿、颅内出血发生情况比较,差异无统计学意义(P>0.05)。胎吸组新生儿中,3例娩出后1 min Apgar评分分别为8、9、6分。剖宫产组新生儿中,仅1例娩出后1 min Apgar评分为7分。胎吸组新生儿中,有9例(30.00%)因黄疸、呼吸急促、窒息等原因转至新生儿科;剖宫产组新生儿中,有4例(17.39%)因黄疸、新生儿低血糖、鼻塞等原因转至新生儿科。胎吸组转科新生儿中,2例(15.38%)出现高总胆红素血症,剖宫产组未出现高总胆红素血症。胎吸组、剖宫产组新生儿动脉血pH值分别为(7.38±0.02)、(7.45±0.02),二者比较差异有统计学意义(P<0.05)。结论Kiwi胎头真空吸引器操作简便,适用范围广,其应用于阴道助产中有效缩短产程,降低剖宫产率、产妇及新生儿相关并发症发生率。展开更多
针对蚕豆种子粒径大、三轴尺寸差异大,充种困难的问题,设计了一种带有平带辅助充种装置的气吸式蚕豆精量排种器。通过对充种过程中的动力学分析阐述了平带辅助充种装置及种子的运动机理;利用计算流体力学和离散元法双向耦合模拟的方法(C...针对蚕豆种子粒径大、三轴尺寸差异大,充种困难的问题,设计了一种带有平带辅助充种装置的气吸式蚕豆精量排种器。通过对充种过程中的动力学分析阐述了平带辅助充种装置及种子的运动机理;利用计算流体力学和离散元法双向耦合模拟的方法(Computational fluid dynamics and discrete element method,CFD-DEM),开展了单因素试验,确定了影响排种器充种性能的主要零部件参数并明晰了平带辅助充种机理;搭建试验台架,选取作业速度、平带输入轴转速和负压为试验因素,合格指数、重播指数、漏播指数为试验指标,进行了二次回归正交组合试验。试验结果表明,影响排种器合格指数的因素主次顺序为:作业速度、负压、平带输入轴转速。对试验结果进行多目标优化,得到最优参数组合为作业速度5.69 km/h、平带输入轴转速395 r/min、负压3845 Pa,对此结果进行排种器性能试验验证,此时合格指数为91.6%、重播指数为3.8%、漏播指数为4.6%,满足蚕豆播种要求。展开更多
文摘Improving the suction performance of centrifugal pumps by using jetting device is presented. The theoretical analysis, experimental study and engineering implementation show that suction performance of centrifugal pump can be improved with jetting device and be used for delivering the liquid media requiring high suction performance, whereas the efficiency and head of the pump will decrease a little. The effect of feed-back jetting on suction performance is the most obvious at design point. The suitable rate of feed-back flow is 2%-5%.
基金National Natural Science Foundation of China(Grant No.52065004,52365030)Lanzhou Municipal Young Talent Innovation Project(Grant No.2023-QN-146)+2 种基金Major Cultivation Project of Collegiate Scientific Research and Innovation Platform of Gansu Provincial Department of Education(2024CXPT-15)Special Project of Gansu Provincial Commissioner for Science and Technology(23CXGA0066)Gansu Agricultural Machinery R&D,Manufacturing and Promotion Application in 2023 Integrated Pilot Project(3-3).
文摘Due to the maize growing agronomy requires ground covered by mulch film in the arid zones of the China Northwest region,the seed-metering device must roll over,break the film,and then throw seeds into soil.However,the uneven ground can cause the seed-metering device to shake,reducing seed-metering performance.To improve the adaptability for different shapes of maize seeds,a air suction wheel type seed-metering device with elastic pad was developed for better seed extraction and bump resistance.Firstly,the advantages and influencing factors of the elastic pad were analyzed through four processes of metering seeds.Secondly,the velocity distributions of six diameters of the suction hole are compared to determine the range with FLUENT.Then,a one-factor experiment was conducted to analyze the pattern of the factors(the seed layer height,the critical vacuum,the rotational speed of the seed disk,and the suction hole diameter)influencing the metering seed performance.Finally,a five-level quadratic rotation orthogonal design was used to optimize the parameters.Results show that the optimal values are that the seed layer height is 40 mm,and the critical vacuum is 2.85 kPa,and the rotational speed of the seed disk is 20.1 r/min.The validation experiment resulted in a 93.79%qualified index,with a 4.02%missing index and a 2.19%multiple index.
文摘目的探讨Kiwi胎头真空吸引器在阴道助产分娩中的应用价值。方法选取2020年7月至2023年3月于扬州大学临床医学院使用Kiwi胎头真空吸引器实施胎头吸引的初产孕妇30例为胎吸组,同时选取计划阴道分娩而后因特殊原因行剖宫产终止妊娠的孕妇23例为剖宫产组。比较2组术中及术后情况及新生儿相关指标。结果2组第二产程时间、产时出血量、产后24 h出血量、产后住院时间及软产道损伤、产后会阴水肿发生情况比较,差异无统计学意义(P>0.05)。2组产后尿潴留发生率比较,差异有统计学意义(P<0.05)。2组新生儿出生体重及头皮血肿、颅内出血发生情况比较,差异无统计学意义(P>0.05)。胎吸组新生儿中,3例娩出后1 min Apgar评分分别为8、9、6分。剖宫产组新生儿中,仅1例娩出后1 min Apgar评分为7分。胎吸组新生儿中,有9例(30.00%)因黄疸、呼吸急促、窒息等原因转至新生儿科;剖宫产组新生儿中,有4例(17.39%)因黄疸、新生儿低血糖、鼻塞等原因转至新生儿科。胎吸组转科新生儿中,2例(15.38%)出现高总胆红素血症,剖宫产组未出现高总胆红素血症。胎吸组、剖宫产组新生儿动脉血pH值分别为(7.38±0.02)、(7.45±0.02),二者比较差异有统计学意义(P<0.05)。结论Kiwi胎头真空吸引器操作简便,适用范围广,其应用于阴道助产中有效缩短产程,降低剖宫产率、产妇及新生儿相关并发症发生率。
文摘针对蚕豆种子粒径大、三轴尺寸差异大,充种困难的问题,设计了一种带有平带辅助充种装置的气吸式蚕豆精量排种器。通过对充种过程中的动力学分析阐述了平带辅助充种装置及种子的运动机理;利用计算流体力学和离散元法双向耦合模拟的方法(Computational fluid dynamics and discrete element method,CFD-DEM),开展了单因素试验,确定了影响排种器充种性能的主要零部件参数并明晰了平带辅助充种机理;搭建试验台架,选取作业速度、平带输入轴转速和负压为试验因素,合格指数、重播指数、漏播指数为试验指标,进行了二次回归正交组合试验。试验结果表明,影响排种器合格指数的因素主次顺序为:作业速度、负压、平带输入轴转速。对试验结果进行多目标优化,得到最优参数组合为作业速度5.69 km/h、平带输入轴转速395 r/min、负压3845 Pa,对此结果进行排种器性能试验验证,此时合格指数为91.6%、重播指数为3.8%、漏播指数为4.6%,满足蚕豆播种要求。
