共查询到18条相似文献,搜索用时 171 毫秒
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介绍了目前国内外常用的几种农用墙排风风机的性能数据,并用通风机相似理论进行了分析和计算,指出了厂家提供的数据中存在的问题,对畜禽舍怎样选择风机,厂家怎样高质量保证风机的特性提出了建议。 相似文献
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基于虚拟仪器技术的风机性能自动测试系统 总被引:6,自引:0,他引:6
针对我国风机性能检测多以手工为主,存在试验手段落后,劳动量大和测试结果不准确等缺点,采用先进的虚拟仪器技术,将传感器技术、计算机技术和测试技术结合起来,建立了基于虚拟仪器技术的风机性能自动测试系统,实现了试验数据的自动采集、风机转速的自动调节、风机运行工况的自动控制、试验数据的正确处理及性能曲线的自动绘制。整个系统具有界面友好、操作方便、功能齐全等优点。试验结果表明本系统增加了试验过程的稳定性,避免了人为的读数误差、计算误差以及相关数据不能同时记录所引起的试验结果偏差,提高了测试精度和试验效率。可广泛应用于科研院所和风机生产厂家,具有较高的推广应用价值。 相似文献
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虽然贯流风机有出风口气流沿轴向分布较均匀等许多优点,但由于其工作原理较复杂,使它在工程中的应用较晚,在农业机械中则应用更少。为了加深对贯流风机性能的理解,探讨其结构参数与运动参数,设计符合联合收割机清选要求的贯流风机,建立了模型风机进行试验,对模型风机进行性能测试与分析,获得了一些实用的数据,如叶片外切角β2取15.33°,据此并利用相似原理,设计了D2=220 mm,D1=154 mm,Z=20,β1=90°,β2=15.33°,θj=170°,θc=165°,θs=25°,h=130 mm,B=1100 mm的贯流风机。该风机用在联合收割机上,转速n=855 r/min,田间作业能满足1.5 kg/s的清选负荷,经测定总损失率1.09%,籽粒破碎率0.05%,籽粒清洁率达98.15%。 相似文献
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采用Microsoft Visual Basic语言,结合Microsoft Access &Excel开发了一种堆肥自动控制系统软件(Temperature-Oxygen-Time,TOT)。软件可实现基于温度、排出气体含氧量和时间三因素对堆肥通风系统进行反馈式控制,最高报警温度、排出气体最低含氧量和阶段划分温度等均可自定义设置,堆肥温度、排出气体含氧量和pH值均可实时监测。系统每10 s刷新显示一次监测结果,每1h自动保存当前采集数据,利用Excel从数据库中读取数据方便对分析结果。模拟运行结果表明,软件能按照预定的要求控制风机开关,能正确计算和记录各个阶段和风机的运行时间,能有效地显示和保存数据。结合Excel,还能快捷地读取温度和含氧量的变化的数据、绘制其变化曲线。 相似文献
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切段式甘蔗收割机排杂风机结构优化与试验 总被引:2,自引:1,他引:1
针对目前机械化收获甘蔗含杂率和损失率高的问题,该研究对广西农业机械研究院有限公司的 4GZQ-180切段式甘蔗收割机风机的内部流场进行了仿真分析并进行了结构优化。该研究表明,原风机叶片和出流室内壁的形状突变、液压马达安装部位凹陷以及主轴阻挡气流均会导致风机内部发生漩涡流动并引起能量损失。优化后的风机叶片前缘和尾缘平滑过渡,提升了叶片性能,优化后的出流室呈圆筒状,主轴轴线与气流主流方向一致,降低了能量损耗,叶轮安装位置远离蔗段,使蔗段不易与叶轮发生碰撞。流量和功率测定结果表明,仿真结果具有较高的准确性。含杂率测定结果表明,优化后的风机在高转速(1 650 r/min)、低行驶速度(1 km/h)时的含杂率与原风机相当,当行驶速度升高至3 km/h后,中(1 350 r/min)、低(1 050 r/min)转速时优化后风机的含杂率明显低于原风机,分别降低了13.91%和20.42%;损失率测定结果表明,优化后风机在低转速时的损失率与原风机最多相差6.48%,当喂入量为1 kg/s时,中、高转速下损失率分别降低了14.77%和28.08%。 相似文献
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清选装置是稻麦联合收获机上的重要工作部件,为了提高谷粒的清洁度和降低清选损失,风机出风口的气流流速应分布均匀。目前在稻麦联合收获机上大多采用的是低压中速离心式风机,其气流沿叶轮宽度方向分布的均匀性比较差。现研究的离心—轴流组合式清粮风机,试验得到的风速标准差为0.5727,变异系数为5%,稳定性系数为95%,比普通离心式风机变异系数低,风速的稳定性系数高。同时离心—轴流组合式风机的出风口风速分布情况是两端较低、中间较高,改变了普通离心式风机的出风口风速分布情况两端较高、中间较低的弊端。 相似文献
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温室细雾风机系统几个主要设计参数对细雾蒸发的影响 总被引:6,自引:2,他引:6
温室细雾风机系统降温的主要缺点是蒸发不完全,地面有积水。文章对温室细雾风机系统在降温过程中的实际蒸发量及细雾风机系统的几个主要设计参数如系统的工作压力、喷嘴高度、细雾的雾化程度等对细雾蒸发的影响进行了试验分析,为解决蒸发不完全问题提供依据 相似文献
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Late Quaternary alluvial fans and paleosols of the Kangra basin,NW Himalaya: Tectonic and paleoclimatic implications 总被引:1,自引:0,他引:1
The paper describes Late Quaternary pedosedimentary sequences of the alluvial fans from the Kangra basin of NW Himalayas for tectonic and paleoclimatic implications. In the proximal part of the Kangra basin three coalescing alluvial fans, namely Rait-Rihlu fans (~ 65 km2), Kangra fans (~ 200 km2), and Palampur fans (~ 170 km2) from west to east evolved due to reactivation of longitudinal and transverse faults and climatic changes during the Late Quaternary. The fans are characterised by subsidence of Rait-Rihlu fans, uplift of Kangra fans and tilting of Palampur fans. The thick (~ 90 m) pedosedimentary sequences exposed along the rivers characterise the dominant formative processes over the fans. The stream flow sediments dominate the Rait-Rihlu fans, whereas the debris flow sediments dominate the Kangra and Palampur fans. The fan sequences are also marked by the formation of strongly developed paleosols on loess (L1–L3 loess paleosols) and weakly developed paleosols on fluvial deposits in response to the tectonics and climate change in NW Himalayas. 相似文献
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不同进风方案下隧道烘干窑热风流场CFD模拟和优化 总被引:5,自引:4,他引:1
隧道烘干窑内同一横截面的热风均匀性影响着物料干燥均匀性和产品质量,而烘干窑入口风速分布直接影响着窑内热风流场的均匀分布。为了解决单一风机直进风隧道烘干窑存在的风速不均匀问题,提出了多种进风结构设想,并利用计算流体力学方法对实际生产的隧道窑进风流场进行数值模拟,研究3种不同的进风方案(4风机、6风机和9风机)对隧道窑内热风流场均匀性的影响。模拟结果表明:6风机方案下隧道窑入口处进风均匀,热风扩散距离短,窑内热风流场整体均匀性较佳,综合性价比最高。研究结果为隧道窑入口进风的设计提供参考。 相似文献
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喷雾与纵向负压通风相结合的封闭牛舍降温效果 总被引:4,自引:4,他引:0
喷雾与纵向负压通风相结合的降温方式在猪舍、禽舍应用广泛,但在肉牛舍应用较少,该试验对喷雾与纵向负压通风相结合在封闭肉牛舍的运行模式进行了探究,并与喷雾结合扰流风机在开放肉牛舍的降温效果进行比较。该试验选用栓系饲养平均体质量273.4 kg的锦江黄牛杂交牛作为试验牛。处理舍安装低压两级雾化喷雾,配合卷帘和风机进行纵向负压通风降温;对照舍安装高压喷雾,结合扰流风机进行降温。两舍喷雾降温系统运行30 d,对环境条件、肉牛生理指标进行测定。结果表明低压两级喷雾在封闭牛舍纵向负压通风条件下喷雾与停止最佳时间均为5~10 min;经两舍喷雾系统降温后,处理舍的日平均温度为(30.4±0.1)℃,比对照舍和舍外分别降低了2.2、6.2℃(P<0.01),而相对湿度为89.7%±0.9%,较对照舍和舍外分别升高了11.3%、35.2%(P<0.01);处理舍试验牛的直肠温度为(38.28±0.03)℃,比对照舍低0.26℃(P<0.01);躺卧比为0.87±0.02,比对照舍高12%(P<0.01);日平均呼吸频率为(43±1)次/min,与对照舍没有显著差异(P>0.05);平均日增质量为(1.38±0.23)kg/d,比对照舍高0.19 kg/d(P>0.05);处理舍售牛可获利1042.39元/(月·头),比对照舍高72.67元/(月·头)。可见封闭牛舍喷雾与纵向负压通风相结合降温效果显著,可改善牛舍环境,有效缓解肉牛热应激,提高生产性能。 相似文献
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Dated shorelines of late Pleistocene pluvial Lakes Lahontan (Great Basin Desert, northwest Nevada) and Mojave (Mojave Desert, eastern California) provide timelines for the assessment of alluvial fan sedimentation at the lake margins during the late Pleistocene to early Holocene. Two sets of alluvial fan systems have been mapped: the Stillwater fans, feeding Lake Lahontan; and the Zzyzx fans, feeding Lake Mojave. Their contrasting morphologies suggest different responses of the two fan systems to late Pleistocene to early Holocene climatic change. At the time the Stillwater fan systems underwent minimal sedimentation, with the catchment hillslopes apparently stable. The Zzyzx fans experienced major changes in water and sediment supply from the catchment hillslopes. There was a major phase of hillslope debris-flow activity, followed by fanhead trenching and distal fan progradation. Both areas were wetter and colder in the late Pleistocene than they are today, but during the transition to the Holocene the Zzyzx area was more likely to experience intense rains associated with the monsoonal penetration of warm moist tropical air into the Southwest. Vegetation reconstructions for the late Pleistocene to the early Holocene suggest that catchment hillslopes in the Mojave supported a desert shrub vegetation, but those in the Stillwaters supported juniper woodland and grasses at low elevations and pine at higher elevations. Contrasts in hillslope vegetation cover together with storm activity may account for the different responses of the alluvial fans to climatic change during the Pleistocene to Holocene climatic transition. After the falls in lake levels of Lakes Lahontan and Mojave in the early Holocene, both areas underwent aridification, resulting in reductions in hillslope vegetation cover. Increased storm runoff led to fanhead trenching and distal progradation of the alluvial fans. Variations in fan style at that time may relate primarily to base-level conditions resulting from different gradients on the exposed lake shores. 相似文献
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Ewa Smolska 《CATENA》2007
The density of gully network in the Suwa?ki Lakeland (northeastern Poland) with typical last-glaciation relief is 0.2 km/km2 on average and locally reaches 1.2 km/km2. Most gullies are isolated but sporadically they create dendritic patterns. The larger gullies are developed along dellies (bowl-shaped, dry valleys) or melt-out valleys. The smaller and shorter gullies occur on the slopes of melt-out depressions and tunnel valleys. Ages of peat covered by fans at the mouths of larger gullies indicate that gully erosion started between 3520 ± 70 to 2240 ± 100 BP. Two different units build the fans and infilled the gullies. The older unit in the lower part of fans is up to 5 m thick, contains sand and gravel that generally originated from the bottom and bank erosion of the gullies and resembles alluvium. The younger unit, about 2–3 m thick, consists of colluvium. The fans at the mouths of smaller and shorter gullies are mainly built of colluvium. The maximal grain diameter in both units is similar, which testifies to a similar intensity of extreme rainfalls. The analysed sediments have different characteristics, which indicate that the source material and depositional changes are linked to forest clearance and farmland expansion starting in the 7th century AD and continuing in the Middle Ages. 相似文献