利用轴向力预测离心压缩机的级密封状态

根据离心压缩机转子所承受的、可实时监测的轴向力与级密封间隙的关系,提出了基于轴向力的离心压缩机级密封状态的预测方法.在分析叶轮两侧缝隙内泄漏气体流动的基础上,采用计算流体动力学方法对其进行仿真,得到轮盘及轮盖上的压力分布,由此计算出轴向力.把不同级密封间隙值及对应的轴向力作为输出、输入向量,对BP神经网络进行训练,以获得在线状态预测模型.测试结果表明,该模型对离心压缩机级密封的状态预测是有效的.     

离心式空压机防喘振优化

针对火电厂离心式空压机的喘振预防及控制策略的优化进行分析;喘振是离心式空压机的固有现象,预防喘振需要找到空压机的空气流量和出口压力的喘振曲线,根据喘振曲线设计变极限流量控制方案;控制策略采用模糊PID控制,针对不同的压力偏差区间找到合适的控制器参数,实现了空压机组适应负荷变化的快速性和稳定性。     

Investigation of model development for deterministic correlations associated with impeller-diffuser interactions in centrifugal compressors

The average-passage equation system(APES)provides a rigorous framework to account for the deterministic unsteady effects by the so-called deterministic correlations(DC),which include both deterministic stress correlations(DCS)and deterministic total enthalpy correlations(DCH).These correlations should be modeled to close the system of equations.In this paper,the distribution of DC in a transonic centrifugal compressor is presented,and its relative importance is revealed.The assumption made by Adamczyk that the pure unsteady fluctuation is significantly smaller than the spatial fluctuation is verified at the impeller-diffuser interface.The decomposition of DCH is also discussed to determine its two different physical mechanisms.Finally,the transport equations in terms of DCS in cylindrical coordinates are derived,and the terms are evaluated to determine the ones that are necessary to model.All these analyses significantly contribute to our model development for DC in centrifugal compressors.     

基于轴向力的离心压缩机级密封的状态预测方法

本文讨论离心压缩机级密封状态的评估问题。根据离心压缩机转子所承受的、可实时监测的轴向力与级密封间隙的关系,提出了基于轴向力的离心压缩机级密封状态的预测方法。在分析叶轮两侧缝隙内泄漏气体流动的基础上,采用计算流体动力学方法对其进行仿真,得到轮盘及轮盖上的压力分布,由此计算出轴向力。把不同级密封间隙值及对应的轴向力作为输出、输入向量,对BP神经网络进行训练,以获得在线状态评估模型。测试结果表明,该模型对离心压缩机级密封的状态预测方法是有效的。     

多级离心风机的气动优化设计

风机的优化改造,对我国工矿企业的节能减排有重大的意义.文章基于通风机气动计算基本理论,针对原多级离心风机吸力不足,效率较差的特点,对其进行优化设计.在制造成本,风机体积等改进限制条件下,通过研究单级的结构和气动性能,分析了叶轮进口气流损失、当量扩张角、预旋、频率共振等因素的影响.经气动复算,结果表明,对叶轮和回流器各增加一片叶片并改变回流器尺寸后,整机压力提高15.3％.     

Simulation of volute tongue of small-size centrifugal compressor

A high speed and small mass-flow-rate centrifugal compressor with original and modified volute tongue shape was simulated by 3D viscous Navier-Stokes equations.A sharp and a round tongue of volute were...     

基于PSO-SVM的离心式压缩机转速模型的研究

针对宁夏某石化公司离心式CO2压缩机透平转速预测难以实现问题,引入PSO-SVM回归模型对离心式压缩机透平转速进行预测.分析选取离心式压缩机透平转速作为模型因变量,通过相关分析从采集量中选取高相关度预测因子,运用粒子群算法选择模型最优参数,利用支持向量机的方法建立模型进行预测,与传统的SVM模型进行对比,该模型得到了良好效果,能够有效预测压缩机透平转速.     

基于ANFIS的离心式压缩机透平转速预测研究

为了解决宁夏石化公司化肥一厂的CO2压缩机透平转速预测的问题,应用自适应神经模糊推理方法,建立了基于Takagi-Sugeno模糊推理的CO2离心式压缩机透平系统性能模型,分析了影响离心式压缩机透平转速的因素.利用石化公司离心式CO2压缩机透平监控系统的实测数据对该网络进行训练,数值模拟表明,训练后模型具有较高的精度及有效性.     

车载燃料电池用离心压缩机的仿真和实验研究

采用计算流体力学仿真和实验方法对车载燃料电池用离心压缩机的工作性能进行了研究.仿真模型利用k-ε方程组模拟压缩机级间气体湍流流动,采用有限体积法对离心压缩机稳态流动进行数值计算.实验结果表明,该仿真模型具有较准确的预测能力.仿真结果显示在叶轮吸力面后部存在造成较大能量损失的二次流动.在离心压缩机仿真和实验研究的基础上,分析了相对马赫数对吸力面附近跨盘盖二次流动的影响以及环量分布和相对马赫数的关系,提出了能够有效抑制吸力面附近二次流动的环量分布.分析结果表明,研制的离心压缩机能够满足燃料电池反应堆的基本要求;在保持叶轮做功能力不变的前提下,通过控制轮盘和轮盖线上环量对子午流线导数值分布,可以有效减弱叶轮间二次流动强度,从而提高离心压缩机的工作性能.     

The effects of gas models on the predicted performance and flow of a centrifugal refrigeration compressor stage

In this paper three perfect gas models with constant specific heat or with variable specific heat and one real gas model based on the gas property tables are respectively considered to implement into the three-dimensional CFD (computational fluid dynamics) analysis of a centrifugal refrigeration compressor stage. The results show that the gas models applied to the CFD code have significant influences on the performance of stage and the flow structures in the stage. Although the thermodynamics operating condition of evolving fluid in the centrifugal refrigeration compressor has a significant deviation from the perfect gas, the perfect gas model with the modified value of gas constant and the variable specific heat offers a good prediction of stage performance. To predict some basic fluid flow parameters and flow structure accurately, the real gas effects should be considered and the reasonably accurate thermodynamic properties based on the analytical gas equation of state or numerical interpolation of gas tables should be applied to the CFD code. Supported by the National Natural Science Foundation of China (Grant No. 50725621)     

浅谈大型空调设备中离心式制冷压缩机的维护

离心式制冷压缩机在大型生产制冷场合应用的十分普遍。以神马实业动力一厂的空调用离心式制冷压缩机为例,着重介绍制冷压缩机的工作原理,并提出具体的日常管理维护措施。     

离心水泵轴封泄漏治理

针对工况的要求和企业设备管理的水平,将离心式水泵的机械密封改造成填料密封,通过合理的结构设计和组合填料使用,改造后的填料密封达到了密封要求,取得了满意效果.     

Performance analysis and improvement of a high flow coefficient centrifugal compressor

Very high flow coefficient centrifugal compressor stages are mostly applied as the first stages of multistage compressors.The performance of this type of stages is critical to the entire centrifugal compressors,but surprisingly little related information is available in the open literature.A centrifugal compressor with high inlet flow coefficient of 0.2,presenting a narrow operating range and unstable running situation even at design speed during the test,is investigated here.To reveal flow details in this centrifugal compressor,numerical simulations have been carried out and indicate that excessive impeller flow diffusion results in the poor performance of this centrifugal compressor.With the same inlet flow coefficient,six redesign cases coming from an in-house one-dimensional analysis program are proposed together with impeller trimming and equal flow area design method for corresponding vaneless diffuser.Performance comparison among these redesign centrifugal compressors is presented and the most suitable one is recommended for test in the future.In addition,three redesign cases with lower inlet flow coefficient developed by means of flow trimming are shown in the end to satisfy potential application areas.Finally,the results in this study can provide valuable reference information for multistage centrifugal compressor design.     

Aerodynamic performance of high-turning curved compressor cascade with boundary layer suction

The impact of boundary layer suction on the aerodynamic performance of a high-turning compressor cascade was numerically simulated and discussed.The aerodynamic performance of a curved and a straight cascade with and without boundary layer suction were comparatively studied at several suction flow rates.The results showed that boundary layer suction dramatically improved the flow behavior within the flow passage.Moreover,higher loading over the whole blade height,lower total pressure loss,and higher passage throughflow were achieved with a relatively small amount of boundary layer removal.The integration of curved blade and boundary layer suction contributed to better aerodynamic performance than the cascades with only curved blade or boundary layer suction used,and the more favorable effect resulted from the weakening of the three dimensional effects of the boundary layer close to the endwalls.     

Influence of volute distortion on the performance of turbocharger centrifugal compressor with vane diffuser

As the geometry of the volute of turbocharger compressor is non-axisymmetric,it causes a distortion at the outlet of the diffuser and influences the upstream components.A distortion model in which a pressure distortion was applied as outlet boundary condition was established to simulate the distortion induced by the volute.It turned out to be sufficient to impose a circumferentially asymmetric pressure distribution at the outlet of the diffuser to replace the volute.Based on the distortion model which was verified,the influence of the amplitude of the distortion on the performance of centrifugal compressor was studied in detail.The results show that the distortion severely harms aerodynamic stability of the investigated compressor.The larger the amplitude of the distortion,the worse the performance of the compressor.The distortion induced by asymmetric volute propagates to upstream components and causes local flow separation at part of diffuser and impeller,and then causes the compressor surge.When the amplitude of the volute distortion is 10%,the stable flow range of the centrifugal compressor decreases to near zero.To authors’knowledge,the relationship between the compressor performance and distortion amplitude is first obtained quantitatively,which provides evidence to improve the performance of turbocharger compressor by decreasing the distortion induced by asymmetric volute.     

Unsteady flow structures in the tip region for a centrifugal compressor impeller before rotating stall

To get an insight into the occurrence and the mechanism of flow unsteadiness in the tip region of centrifugal compressor impellers, the flow in Krain’s impeller is investigated by using both steady and unsteady RANS solver techniques. It is found that the flow unsteadiness on the pressure side is much stronger than that on the suction side. The periodical frequency of the unsteady flow is around half of the blade passing frequency. The originating mechanism of the flow unsteadiness is illustrated with the time-dependent tip leakage flow and blade loading at the tip region. Due to the blockage caused by the joint effects of broken-downed tip leakage vortex, separated fluids and tip leakage flow at downstream, a low pressure region is formed on the pressure side, consequently the blade loadings is altered. In turn, the changed blade loadings will alter the intensity of tip leakage flow. Such alternative behavior finally results in the periodic process. By comparing the calculated flow field in the cases of single-passage and four-passage models, it is confirmed that the investigated flow unsteadiness is confined in each single passage, as no phase differences are found in the model of four passages. This is different from the situation in axial compressor when the rotating instability is encountered. The flow unsteadiness only occurs at the working conditions with small mass flow rates, and the oscillation intensity will be enhanced with the decrease of mass flow rate. When the mass flow rate is too small, the flow unsteadiness in a single passage may trigger rotating stall, as the disturbance propagates in the circumferential direction.     

Effect of impeller reflux balance holes on pressure and axial force of centrifugal pump

The size of impeller reflux holes for centrifugal pump has influence on the pressure distribution of front and rear shrouds and rear pump chamber, as well as energy characteristics of whole pump and axial force. Low specific-speed centrifugal pump with Q=12.5 m3/h, H=60 m, n=2950 r/min was selected to be designed with eight axial reflux balance holes with 4.5 mm in diameter. The simulated Q-H curve and net positive suction head(NPSH) were in good agreement with experimental results, which illustrated that centrifugal pump with axial reflux balance holes was superior in the cavitation characteristic; however, it showed to little superiority in head and efficiency. The pressure in rear pump chamber at 0.6 times rate flow is 29.36% of pressure difference between outlet and inlet, which reduces to 29.10% at rate flow and 28.33% at 1.4 times rate flow. As the whole, the pressure distribution on front and rear shrouds from simulation results is not a standard parabola, and axial force decreases as flow rate increases. Radical reflux balance holes chosen to be 5.2 mm and 5.9 mm in diameter were further designed with other hydraulic parts unchanged. With structural grids adopted for total flow field, contrast numerical simulation on internal flow characteristics was conducted based on momentum equations and standard turbulence model(κ-ε). It is found that axial force of pump with radical reflux balance holes of5.2 mm and 5.9 mm in diameter is significantly less than that with radical reflux balance holes of 4.5 mm in diameter. Better axial force balance is obtained as the ratio of area of reflux balance holes and area of sealing ring exceeds 6.     

利用雕鸮羽毛的消音特性降低小型轴流风机的气动噪声

为降低轴流风机的气动噪声,借鉴了雕鸮羽毛的消音机理,将其羽毛的消音特征以条纹结构和锯齿形态的形式,在轴流风机叶片上进行重构,设计了耦合仿生轴流风机。同时采用试验优化的方法,与原轴流风机进行了模型对比试验,研究了条纹及锯齿参数对风机叶片气动噪声的影响。结果表明,耦合仿生轴流风机具有较低的气动噪声值。在1000、1100、1200、1300和1400r/min五种转速下,耦合仿生轴流风机的A声级值最大可分别降低4.9、4.5、4.6、4.9和5.8dB。     

Aerodynamic design of transonic fan/compressor by 3D viscous RNS combined with genetic algorithms

This paper presents an aerodynamic design of a small transonic fan by 3D viscous RNS solver combined with genetic algorithms.The aerodynamic design system based on the 3D viscous RNS solver reduces the dependency on the design experience for designers.Furthermore the optimum with genetic algorithms is an effective method for improving the transonic fan performance as a part of the design system.The design result showed that the transonic fan designed by this method reaches the design requirement even with more efficiency value.     

Improved fast model migration method for centrifugal compressor based on bayesian algorithm and Gaussian process model

Design and operation optimization of centrifugal compressor are always based on an accurate prediction model, however, due to the short time operation and lack of data information, it is difficult to get an accurate prediction model of a new centrifugal compressor in time. This paper applies an improved fast model migration method (FMM method) to develop the model of the new centrifugal compressor. The method adapts a Gaussian Process (GP) model from an old centrifugal compressor to fit a new and similar centrifugal compressor, and the adaptation is conducted by a scale-bias adjustment migration technology. In order to obtain the better estimated parameters of migration, Bayesian method, which takes the prior knowledge into consideration, is used in the sequential experiment. The approach is validated by a specific simulation bench. The results indicate that the applied approach can achieve a better prediction precision with fewer data of the new centrifugal compressor compared to pure GP method, and can model the new centrifugal compressor rapidly.