共查询到19条相似文献,搜索用时 140 毫秒
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流场分布不均匀的袋式除尘器除尘效率会大幅度降低,因此开发分布式压力监测系统。用ZigBee技术开发终端采集节点、路由节点和中心分站等结构,节点的压力数据通过ZSC31050采集并利用温差程序进行补偿,校准后的压力数值通过ZigBee网络传送数据,利用240 cm除尘器滤袋检测实验分析压力。试验结果显示当喷吹压力为30 kPa、喷吹距离为240 cm时,检测长滤袋各点的分布压力,并测量喷口的不同压力。结果显示监测系统可以精确识别出袋式除尘器的压力分布。 相似文献
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《现代制造技术与装备》2016,(12)
筒状袋式除尘器的入口位置及入口方式的不同,对除尘器内部的气流平稳影响很大。采用经典流体力学软件FLUENT,对筒状袋式除尘器的入口位置及入口方式进行优化仿真,使其内部的气流更加平稳,压力分布更加均匀。结果表明,入口采用切入式,可有效稳定箱体内部气流和减少对滤袋的冲刷;入口逐渐展开、入口位置靠近除尘器上半部分,能有效均衡袋式除尘器的气流和压力分布,减少滤袋所受的冲刷和压力。实验也表明,滤袋底部所受压力较大时,应加密滤袋底部的支撑,有助于将滤袋所受压力转移到支架上。定期顺时针转动滤袋,可使滤袋所受压力时间均衡,有效延长滤袋的使用寿命。 相似文献
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以平整机吹扫系统中三维空气喷嘴为研究对象,确定了喷嘴的结构参数;基于流体力学的基本方程和RNG k-ε湍流模型,建立了吹扫射流的数学模型。从喷嘴内部以及喷射外流场的流动状态、喷嘴轴线上的速度和压强分布、靠近钢板处的气流分布情况三个方面,对吹扫流场进行了稳态分析;采用自由表面模型,对吹扫流场和吹扫效果进行了非稳态分析。研究表明:该类型的喷嘴外部流场成窄带形分布;气流冲击钢板后,在钢板上形成冲击区和漫流区;所选喷嘴在高度为150 mm时沿着钢板宽度方向形成的打击范围为0.06 m,并且经过0.06 s,冲击点处的水分已经被吹扫干净,但是沿着钢板长度方向还有部分水分残留。 相似文献
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涡喷发动机产生的高温高速尾气被导气罩引致喷嘴,以320m/s的喷射速度、873K的高温和102.4m3/s的流量喷射地面冰层,以清除重要和关键场所的路面薄冰层。使用计算流体力学方法,数值模拟分析了单相流形成的压力场、速度场和温度场,以及冰融后形成的水雾粒子在两相流场中的分布、速度和运移状态。数值模拟结果表明,高温高速喷射气流所形成流场的温度场,高温层与冰层直接接触,路面薄冰快速形成水雾;水雾与气流混合形成高密度固相梯度分布的高速移动两相流,瞬时移出计算域以外。涡喷除冰实践和数值模拟结果均验证了涡喷热融除冰的快速有效性。 相似文献
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利用CFD方法对508钢管吹灰系统的关键部件进行参数优化,改变喷嘴直径,对吹灰系统进行仿真分析。研究了不同参数对吹灰系统内部流场分布的影响。针对不同参数条件下的钢管端部漏气量进行分析,得到了相对优化的喷嘴尺寸结构方案。仿真结果对实际工程中具有一定的指导意义。 相似文献
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Hadi Hoghooghi Mahdi Nili Ahmadabadi Mojtaba Dehghan Manshadi 《Journal of Mechanical Science and Technology》2016,30(5):2059-2067
The goal of wind tunnel design is to generate a uniform air flow with minimum turbulence intensity and low flow angle. The nozzle is the main component of wind tunnels to create a uniform flow with minimal turbulence. Pressure distribution along nozzle walls directly affects the boundary layer thickness, pressure losses and non-uniformity of flow velocity through the test section. Although reduction of flow turbulences and non-uniformity through the test section can be carried out by nozzles with high contraction ratio, it increases the construction cost of the wind tunnel. For decreasing the construction cost of nozzle with constant test section size and mass flow rate, the contraction ratio and length of nozzle should be decreased; that causes the non-uniformity of outlet velocity to increase. In this study, first, three types of nozzle are numerically investigated to compare their performance. Then, Sargison nozzle with contraction ratio of 12.25 and length of 7 m is scaled down to decrease its weight and construction cost. Having scaled and changed to a nozzle with contraction ratio of 9 and length of 5 m, its numerical solution reveals that the non-uniformity of outlet velocity increases by 21%. By using the Ballspine inverse design method, the pressure distribution of the original Sargison nozzle is first scaled and set as the target pressure of the scaled down nozzle and geometry correction is done. Having reached the target nozzle, numerical solution of flow inside the optimized nozzle shows that the non-uniformity just increases by 5% in comparison with the original Sargison nozzle. 相似文献
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Currently, many studies have been made for years on dimensions of pneumatic nozzle, which influence the flow characteristic of blowing system. For the purpose of outputting the same blowing force, the supply pressure could be reduced by decreasing the ratio of length to diameter of nozzle. The friction between high speed air and pipe wall would be reduced if the nozzle is designed to be converging shape comparing with straight shape. But the volume flow and pressure, discussed in these studies, do not describe energy loss of the blowing system directly. Pneumatic power is an innovative principle to estimate pneumatic system's energy consumption directly. Based on the above principle, a pulse blowing method is put forward for saving energy. A flow experiment is carried out, in which the high speed air flows from the pulse blowing system and continuous blowing system respectively to a plate with grease on top. Supply pressure and the volume of air used for removing the grease are measured to calculate energy consumption. From the experiment result, the pulse blowing system performs to conserve energy comparing with the continuous blowing system. The frequency and duty ratio of pulse flow influence the blowing characteristic. The pulse blowing system performs to be the most efficient at the specified frequency and duty ratio. Then a pneumatic self-oscillated method based on air operated valve is put forward to generate pulse flow. A simulation is made about dynamic modeling the air operated valve and calculating the motion of the valve core and output pressure. The simulation result verifies the system to be able to generate pulse flow, and predicts the key parameters of the frequency and duty ratio measured by experiment well. Finally, on the basis of simplifying and solution of the pulse blowing system's mathematic model, the relationship between system's frequency duty ratio and the dimensions of components is simply described with four algebraic equations. The system could be designed with specified frequency and duty ratio according to the four equations. This study provides theoretical basis for designing energy-saving air blowing system. 相似文献
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定向喷嘴布置对PDC钻头井底流场影响研究 总被引:1,自引:0,他引:1
定向喷嘴布置的方式对PDC钻头的井底流场将有很大的影响,尤其是能改变PDC钻头的水力性能,因而研究定向喷嘴布置具有重要的意义.本文分析了喷嘴的不同布置方法,并通过数值方法模拟其对PDC钻头井底流场的影响.结果表明:在不完全对称布置方案的冲击区,在射流刚开始从喷嘴处流出去,但还未接触井底,各喷嘴射流处于衰减地带之内,这样的话将对钻头的清洗和携带岩屑离开井底非常有效果;在漩涡区,喷射角大、距钻头中心远的喷嘴射流则对清洗和携带井壁附近的岩屑起主要作用,喷射角小、距钻头中心近的喷嘴射流则对清洗和携带井底中心的岩屑起主要作用;在刀翼上的附面层由于周围喷嘴的影响,刀翼切削面低速区明显减少,剪应力增大,更好地预防、清除PDC钻头的泥包.最终达到提高机械钻速的效果. 相似文献
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激光制造中载气式同轴送粉粉末流场的数值模拟 总被引:6,自引:0,他引:6
应用气固两相流理论对载气式同轴送粉系统中粉末流出送粉喷嘴后的粉末流场进行模拟计算,研究分析粉末流场浓度分布规律及粉末流参数(聚焦焦距和聚焦半径)的变化规律,计算结果与数字粒子图像测速的试验结果吻合较好.结果表明,载气式同轴送粉系统中,送粉喷嘴结构参数一定时,粉末流浓度和粉末流参数受送粉量及送粉气流量的影响.送粉气流量主要影响送粉喷嘴出粉口处粉末流的速度,对粉末流浓度分布和粉末流聚焦参数影响较小;送粉量增加,聚焦点处浓度值增大,粉流聚焦焦点略微下移,焦距处半径增大,聚焦焦深减小.建立粉末流简化物理模型,所建模型对同轴送粉喷嘴的设计和性能优化具有参考价值. 相似文献
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为了减小房屋装修后室内甲醛对人体的危害,了解不同通风方式及通风速度下室内甲醛浓度的分布特征是关键。本文采用CFD方法,模拟2种基本通风方式室内气流组织的流动形式,研究了不同通风方式、不同送风速度对室内甲醛的浓度分布的影响,数值模拟表明:与异侧送回风通风方式相比,同侧送回风形式更能有效减小室内甲醛的浓度,因而室内通风方式应优先选择同侧送回风。在同侧送回风气流组织形式下,送风速度过小或过大均致使人站或坐高度平面上甲醛浓度增大,因而应根据甲醛的散发强度,选择合适的送风速度,如在本文中送风速度以2m/s左右为宜。优化室内污染物扩散的通风形式,对室内通风设计和气流组织的研究具有一定的指导意义。 相似文献
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采用实验和数值模拟相结合的方法对自耦合射流的流动特性进行了研究。研究结果表明:在紧邻喷口的法向距离内,涡对周期性地生成、破碎和融合,在某个法向距离上形成较为稳定的连续性射流;自耦合射流在发展过程中呈现出在短轴方向急剧扩展,而在长轴方向先向内汇聚、再向外发展的特征;自耦合射流的速度分布与常规射流的速度分布相比,两者在喷口水平方向上均呈现比较规律的速度自模的特征,但在喷口长轴方向,接近喷口的位置速度分布呈现明显的对称马鞍状,随着离喷口法向距离的增加,这种马鞍状的分布逐渐消失。 相似文献
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为解决径向水平井钻进过程中破岩效率和自进能力的问题,设计了一种自进式旋转射流钻头。运用数值模拟方法,采用RNG k-ε湍流模型对所设计射流钻头的内外流场进行了三维流动特性分析,并分析了射流钻头结构参数对喷嘴流场特性的影响规律,进一步优化了自进式旋转射流钻头。结果表明,自进式旋转射流喷嘴外流场的轴心速度在喷嘴中心线上的速度最大,随着径向半径的增大,轴向速度迅速减小;切向速度沿喷嘴径向呈现出经典的"N"形分布,有利于增大射流破碎岩石的深度和破碎面积;径向速度呈轴对称分布,存在明显的漫流层,有助于岩屑的脱离;自进式旋转射流钻头导向叶轮的螺距和导叶数量,对射流速度有着重要的影响;喷嘴直径对射流流场特性的影响较大。经过优化,得到射流钻头的叶轮螺距16mm,导叶数为2,喷嘴直径为1mm。 相似文献