Numerical Investigation of the Aerodynamic Performance Affected by Spiral Inlet and Outlet in a Positive Displacement Blower

The flow in the positive displacement blower is very complex.The existing two-dimensional numerical simulation cannot provide the detailed flow information,especially flow characteristics along the axial direction,which is unfavorable to improve the performance of positive displacement blower.To investigate the effects of spiral inlet and outlet on the aerodynamic performance of positive displacement blower,three-dimensional unsteady flow characteristics in a three-lobe positive displacement blower with and without the spiral inlet and outlet are simulated by solving Navier-Stokes equations coupled with RNG k-ε turbulent model.In the numerical simulation,the dynamic mesh technique and overset mesh updating method are used.The computational results are compared with the experimental measurements on the variation of flow rate with the outlet pressure to verify the validity of the numerical method presented.The results show that the mass flow rate with the change of pressure is slightly affected by the application of spiral inlet and outlet,but the internal flow state is largely affected.In the exhaust region,the fluctuations of pressure,velocity and temperature as well as the average values of velocity are significantly reduced.This illustrates that the spiral outlet can effectively suppress the fluctuations of pressure,thus reducing reflux shock and energy dissipation.In the intake area,the average value of pressure,velocity and temperature are slightly declined,but the fluctuations of them are significantly reduced,indicating that the spiral inlet plays the role in making the flow more stable.The numerical results obtained reveal the three-dimensional flow characteristics of the positive displacement blower with spiral inlet and outlet,and provide useful reference to improve performance and empirical correction in the noise-reduction design of the positive displacement blowers.

Numerical Simulation of Unsteady Discharge Flow with Fluctuation in Positive Discharge Blower

The operating performance of positive discharge blower is markedly influenced by the pulsation of the discharge flow, but difficult to be measured with experimental methods. The internal and discharge flow of positive discharge blower with involute type three-lobe are numerically investigated, both in air cooling and countercurrent cooling conditions by means of computational fluid dynamics （CFD）. The unsteady compressible flow equations are solved using RNG x-ε turbulent model. The finite difference method and the second order upwind difference scheme are applied into discrete equations. In the numerical simulation, the dynamic mesh techniques are used to approach the rotating displacement of cell cubage and the alterability of inlet, outlet flow area. The non-uniform mesh is applied to the rotor-stator coupled area. The reliability of the numerical method is verified by simulating the inner flow and comparing with the semi-empirical theory. The flow flux curves and the distributing of velocity vector showed obvious vortex motion in all the discharge process, both in air cooling and countercurrent cooling conditions. These vortexes with different positions, intension and numbers at different rotating angles have remarkable influences on the discharge flux. For air cooling, the vortex produced a second pulsation with big-amplitude in a cycle, and led to the early appearance of maximum of backflow. For countercurrent cooling, the frequency of pulsation increased due to the pre-inflow, but the backflow at the outlet is prevented, also the pulsation strength has greatly decreased.

Unsteady Flow Simulations in a Three-lobe Positive Displacement Blower

To improve the performance of the positive displacement blower, it is imperative to understand the detailed internal flow characteristics or enable a visualization of flow status. However, the existing two-dimensional unsteady, three-dimensional steady or quasi-unsteady numerical simulation and theoretical analysis cannot provide the detailed flow information, which is unfavorable to improve the performance of positive displacement blower. Therefore, the unsteady flow characteristics in a three-lobe positive displacement blower are numerically investigated by solving the three-dimensional, unsteady, compressible Navier-Stokes equations coupled with RNG k-e turbulent model. In the numerical simulation, the dynamic mesh technique and overset mesh updating method are adopted. Due to the air being compressed in the process of the rotors rotating, the variation of the temperature field in the positive displacement blower is considered. By comparing the experimental measurements and the numerical results on the variation of flow rate with the outlet pressure, the maximum relative error of the flow rate is less than 2.15% even at the maximum outlet pressure condition, which means that the calculation model and numerical computational method used are effective. The numerical results show that in the intake region, the fluctuations of the inlet flow are greatly affected by the direction of the velocity vectors. In the exhaust region, the temperature changes significantly, which leads to the increase of the airflow pulsation. Through analysis on the velocity, pressure and temperature fields obtained from the numerical simulations, three-dimensional unsteady flow characteristics in the positive displacement blower are revealed. The studied results will provide useful reference for improving the performance and empirical correction in the design of the positive displacement blower.

DISTRIBUTION LAW OF RANDOM UNBALANCE RESPONSE OF MULTISTAGE BLOWER

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Theoretical, Experimental and Numerical Investigations of the Effect of Inlet Blade Angle on the Performance of Regenerative Blowers

Regenerative machines allow high heads at small flow rates and present performance curves with very stable features. This research includes a study of the effect of four inlet flow angles (90°, 115°, 125° and 135°) of the blade at outlet flow angle of 90° on the performance of regenerative blower at rotation speed of 3000 rpm and at different flow rates. Investigation and comparison of the experimental results with both one-dimensional theoretical model and numerical CFD technique using CFX-ANSYS 16.1 are done. The numerical CFD analysis show that the flow enters the impeller from the blade side (about 65% of the blade side area) and leaves from the blade tip and blade side (the remaining 35% from the blade side area). According to this observation, a mathematical model that is based on momentum exchange theory to handle one inlet angle and two exit angles for the regenerative blower impeller blades is proposed. Consequently, the experimental work is carried out by two steps. The first step is done by studying the effect of inlet blade angle of 90° and analyzing the results by using the CFD analysis. The CFD results show shock losses and vortices behind each blade at the inlet flow regions. To reduce these losses, an increase of the inlet blade angle in a range between 25° to 45° is proposed. The second step is the splitting of this angle range to three inlet blade angles of 115°, 125° and 135° in order to study and analyze the CFD results for these angels. The CFD analysis shows the disappearance of the shock losses and vortices that are formed behind the blade of angle 90°. The experimental results show that the pressure head and the efficiency depend strongly on the blade inlet and outlet flow angles as well as on the blade geometry. The results also show that the best blower performance can be obtained at an inlet flow angle of 125°, and this is confirmed by CFD simulation analysis. Finally, it is shown that the proposed one-dimensional model yield results that are in a good agreement with the experimental results.

Shape Optimization of a Regenerative Blower Used for Building Fuel Cell System

This paper describes the optimal design of a Cathode blower used for a building fuel cell system. The Cathode air blower has a regenerative blower type. Two design variables, extension angle and number of impeller blade are introduced to enhance the blower performance. Pressure and efficiency of the blower are selected as an object function, and the optimal design is performed by a response surface method. Three-dimensional Navier-Stokes equations are introduced to analyze the performance and internal flow of the blower and to find the value of object function for the training data. Throughout the design optimization, it is found that an extension angle is effective to increase blower efficiency in the blower. The pressure rise for the optimal blower is successfully increased up to 3.17% compared with that of reference one at the design flow rate. It is noted that low velocity region disturbs to make strong recirculation flow in the each blade passage, thus increases local pressure loss. Detailed flow field inside a regenerative blower is also analyzed and compared.

Hydraulically Powered Wood Chip Blower in Test and Its Use Opportunity in Biofuel Supply Chain

Most forest chips are delivered to large-sized, combined heat and power plants in Finland. In this study, we introduce and demonstrate the small-scale delivery of forest wood chips to potential clients, with the wood chips being delivered in a container truck and pneumatically blown into a storage facility. This arrangement of wood chips being blown through a pipe into a storage eliminates the ground handling while requiring a relatively small space. In the demonstration tests, we tested the volumetric flow of biomass in the hose and its noise level while the blower was blowing the material and the flow speed of the material in the hose. This study discusses the test conditions in which the compatibility and suitability of the truck and its hydraulic system were used in conventional chip delivery in Finland and the selected blower type was investigated. According to the results, the biomass volume flow was higher (~0.46 m3/min) when the blower revolution was lower (2392 - 2566 RPM). However, when the RPM was increased to ~3000, the volumetric flow decreased to ~0.24 m3/min. Similarly, the speed of the chips was higher with a lower RPM;29.9 m/s at an RPM of 2400 and 25 m/s at an RPM of 2700. This is potentially due to both the blower and screw conveyer using the same power source. Additional optimization research would be needed to conclusively state the root cause of this phenomenon. On the other hand, chips from pruned stems had better flow than the chips from whole trees, since chips from whole tree have a wider range of chips sizes, including 1.3% of chips being in the range of 31.5 - 40 mm. The larger chips clogged the hose, which hindered the flow. Finally, the noise tests showed that it was louder at 0 degrees, which contrasted with the situation for the blower, with an aside at 90 degrees.

两代宾利极速赛车 欧陆GT3和BIRKIN“BLOWER”

当2015赛季落下帷幕时,宾利两代战车——欧陆GT3和传奇的4.5L"Blower"汇聚一堂,其同庆祝本赛季的出色表现。现役的GT3和其来自1929年、曾创造辉煌战绩的先辈战车,在位于银石赛道的英国赛车手俱乐部(BRDC)门前欢聚一堂。英国赛车手俱乐部于1928年成立,是由宾利小子、勒芒冠军Dudley Benjafield创立的赛车运动组织。这两台战车年代相差80余年,但是它们身上同样流淌着宾利对创新、竞技以及最重要的速度的满腔热血。

Cycloblower罗茨鼓风机的故障检修和调试

分析了Cycloblower罗茨鼓风机在运行中出现的故障及其原因 ,介绍了机器的修复过程和调试、使用要求。

Modelling and verification of a new Roots blower profile based on analysis of performance of different leaf contour

The rotor of a Roots blower is the key component relating to its capability, so the profile design of the rotor in a Roots blower is extremely important. We focused on the modelling and verification for a novel Roots blower tooth profile based on the performance analysis. By comparing the area utilization coefficient and the ratio of several traditional rotor profiles, we proposed a new rotor profile. Then, we further accomplished the mathematical modelling of the proposed rotor profile and the computational fluid dynamics(CFD) simulation, and obtained the Roots blower outlet flow monitoring curves. Finally, we verified the characteristics by a physical experiment.

挥发窑鼓风管的关键点识别及其摆放位置监测

窑头鼓风管的摆放位置是影响氧化锌挥发窑燃烧状态的重要操作参数之一,现仍由人工看火来手动调节,同时现场没有为挥发窑的运行优化记录完善的鼓风状态数据,也难以及时发现鼓风管被窑内渣块击中等安全隐患.针对上述问题,本文提出一种基于关键点识别的鼓风管位置监测方法.首先,文章对从窑头看火口采集的火焰视频数据集设计一种邻域关键点辅助的数据扩充方法,并构建级联金字塔网络(CPN)来预测鼓风管管口中心点的位置;然后,本文提出一种基于多帧图像的聚类分析算法来消除因烟尘遮挡所产生的异常点,并采用一种量化指标来实现对挥发窑鼓风管摆放位置的实时感知与记录;最后,本文基于现场采集的火焰视频数据进行了对比实验,结果表明所提出的关键点检测模型精度高、鲁棒性强,且鼓风管位置的量化准确率高达92.3%.

透平风机与纸机真空系统的匹配设计方法

本课题主要在湿纸幅流阻特性分析的基础上,探讨了透平风机与湿纸幅的气动匹配特性,并以实际生产线技改为例,介绍了应用透平风机改进真空系统的相关设计准则。

VPSA制氧系统中离心鼓风机变工况调节规律研究

为提升离心鼓风机的变工况性能,以某真空变压吸附(VPSA)制氧系统中的离心鼓风机为研究对象,采用数值计算的方法分别对转速、扩压器角度单独调节以及二者联合调节时离心鼓风机的性能变化规律进行了研究。结果表明,相较于固定式,联合调节的工作压比范围扩大42%,可以使离心鼓风机在全压比范围内保持高效稳定运行;通过建立效率与转速、扩压器角度、压比之间的函数模型,采用内点法寻优得出了联合调节的最佳控制方案,为离心鼓风机的高效运行提供了依据。最后为验证寻优结果的可靠性,结合离心鼓风机的实际工作压比变化规律,按照最佳控制方案对试验模型的转速与扩压器角度进行联合调节,经测量可使离心鼓风机保持效率为87%以上持续运行。

CCPP加压站系统优化

分析了CCPP加压站存在的问题,制定了CCPP加压系统的优化方案。阐述了优化措施实施过程,并对于优化后试运行中出现的问题加以解决。实现了提升CCPP发电机组的发电效率,保障了CCPP加压站的稳定运行。

基于PLC的小盒外观检测相机镜头除尘设计

包装机小盒外观视觉检测多采用高速、高清的彩色CCD相机,利用图像处理器把拍摄照片所有特征提取出来,逐个进行比对分析,从而找出烟包缺陷部分。应用于FOCKS-350S包装机的ZNO系列小盒外观检测相较于其他机型,在401拐角处增加了烟包正面检测。由于相机镜头向上拍摄的缘故,在实际生产中相机镜头经常被掉落的烟末和灰尘遮挡。使得图像处理器对相机拍摄的烟包表面图片识别错误造成误检。针对以上问题在相机镜头前端增加正压吹风装置来解决相机落尘误检问题。通过PLC中的时钟功能,完成正压吹风除尘的启停切换。经验证,安装吹风除尘装置后,小盒外观检测误剔率减少了86%左右,大大降低了卷烟包装材料的消耗,提高了小盒外观检测剔除的准确率,进而减少了生产过程中小盒外观的质量隐患。

高压干式移磁无级调压软起动装置和就地无功补偿装置在制氧站的应用

以某铅冶炼厂制氧站改扩建项目为例,介绍高压干式移磁无级调压软起动装置和就地无功补偿装置的工作原理及其在罗茨鼓风机上的应用、高压干式移磁无级调压软起动装置和就地无功补偿装置的选型及参数计算、罗茨鼓风机配电系统设计、罗茨鼓风机现场运行效果。

某水泥厂SCR脱硝反应器压差升高原因及对策

针对某水泥厂SCR脱硝装置运行中反应器压差增大、耙式吹灰器耗气量降低等问题,分析了催化剂层堵塞的主要原因是耙式吹灰器故障及耙杆堵塞;同时从吹灰器设计、生产运行和吹灰介质等方面,逐项分析了引起耙式吹灰器堵塞的可能因素。对催化剂和吹灰器清堵后,反应器压差显著降低,脱硝效率也恢复到80%以上,同时通过在吹灰器提升阀上设置正压防堵管路,可防止飞灰入侵吹灰孔堵塞吹灰器,并提出运行优化建议。

鼓风机防喘振控制研究

为解决鼓风机喘振现象对设备本身造成的影响,甚至会发生爆炸和火灾等事故的问题,在对高炉炼钢工艺和鼓风机简单概述的基础上,对鼓风机喘振现象的判断机理、影响因素和防喘振控制原理进行深入分析,最终得出基于鼓风机实时工况点与喘振点能量头比值为判断是否出现喘振现象的依据,并确定不同比值对应的放风阀开度之间的关系,为指导鼓风机实践应用的防喘振控制奠定基础。

鼓风机蜗壳的优化

为进一步提升离心鼓风机的工作效率和工作性能,基于SolidWorks软件构建三维模型,在完成网格划分以及入口条件设置的基础上导入Fluent软件开展数值模拟研究,重点对比蜗壳形状为梯形、圆形和偏心以及蜗壳锥角为22.5°、35°和45°对应的离心鼓风机的出口静压力、多变效率、全压效率以及轴功率等参数,研究成果可指导鼓风机蜗壳的优化。