【标题】Circumferential groove on flow field and pressure fluctuation intensity of a semi-open centrifugal pump under design condition
【参考中译】环向槽对半开式离心泵流场及压力脉动强度的影响
【类型】 期刊
【关键词】 Centrifugal pump; Circumferential groove; Pressure fluctuation; Tip leakage vortex; Flow field; Entropy production
【参考中译】 离心泵；周向槽；压力脉动；叶尖泄漏涡；流场；熵产生
【作者】 Like Wang; Xingqi Luo; Jinling Lu; Jianjun Feng; Guojun Zhu; Wei Wang
【摘要】 The tip leakage flow (TLF) generated by the tip clearance has adverse effect on the performance of the impeller and increases pressure fluctuation. To suppress the effect of TLF on the instable flow in a semi-open centrifugal pump, the circumferential groove method is proposed in this paper. The effect of the circumferential groove on the internal flow and pressure fluctuation under the design condition is studied by combining numerical simulation with experiment. The results show that the head and efficiency were reduced by 1.1% and 1.0%, respectively. However, the circumferential groove provided a circumferential channel for leading edge overflow. The fluid in the groove formed a jet near the low-pressure region, which can effectively disperse the low-energy fluid of the blade inlet. The initial position and trajectory of the tip leakage vortex (TLV) move downstream, which decreases the relative flow angle and low-velocity region. The flow field in the blade tip region was improved remarkably. The low-frequency pressure fluctuation in the pressure surface and tip clearance of the blade inlet was suppressed by the circumferential groove, and pressure pulsation intensity decreased by 50% and 66%, respectively.
【参考中译】 叶顶间隙产生的叶尖泄漏流对叶轮的性能有不利影响，增加了叶轮的压力脉动。为了抑制TLF对半开式离心泵内不稳定流动的影响，本文提出了一种周向槽法。采用数值模拟与实验相结合的方法，研究了在设计工况下，周向槽对内部流动和压力脉动的影响。结果表明，采用该方案后，水头降低了1.1%，效率降低了1.0%。然而，周向凹槽为前沿溢流提供了周向通道。槽内流体在低压区附近形成射流，能有效分散叶片进口的低能流体。叶尖泄漏涡(TLV)的初始位置和轨迹向下游移动，减小了相对流动角和低速区。叶尖区的流场得到了显著的改善。周向槽抑制了叶片进口压力面和叶尖间隙的低频压力波动，压力脉动强度分别降低了50%和66%。
【来源】 Proceedings of the Institution of Mechanical Engineers 2023, vol.237, no.24
【入库时间】 2024/3/28
【标题】Method of predicting valve seal leakage considering deflection of the spool
【参考中译】考虑阀芯偏移的气门密封泄漏预测方法
【关键词】 Spool deflection; Lattice leakage theory; Microscale leakage channel; Leakage rate; Contact; Rough surface
【参考中译】 线轴偏转；晶格泄漏理论；微尺度泄漏通道；泄漏率；接触；粗糙表面
【作者】 Fei Guo; Chong Xiang; Qiyao Chen; Maoqi Zheng; Wujiang Yu; Yuming Wang
【摘要】 The small angular deflection of the spool under the action of non-equilibrium force is a main reason for valve seal failure. In the present study, a prediction model of the valve seal leakage was established considering the sectional shape and channel height of the leakage channel. The effect of spool deflection on the leakage rate was analyzed quantitatively from the results of three-dimensional finite element mechanical analysis. The microscale leakage channel of a contact deformation surface was then generated through the reconstruction of the rough surface with nanoscale precision, deterministic rough-peak contact analysis, and lattice leakage theory. The results showed that the spool deflection was the key factor affecting the leakage rate. The leakage rate was measured on a self-built experimental platform, and the experimental results verified the accuracy of the theoretical calculations.
【参考中译】 阀芯在非平衡力作用下产生的小角偏移是导致气门密封失效的主要原因。本文建立了考虑泄漏通道截面形状和通道高度的气门密封泄漏预测模型。利用三维有限元力学分析结果定量分析了阀芯偏移对泄漏率的影响。通过对粗糙表面的纳米级精度重构、确定性粗糙峰接触分析和晶格泄漏理论，生成了接触变形表面的微尺度泄漏通道。结果表明，阀芯偏移是影响泄漏率的关键因素。在自行搭建的实验平台上测量了泄漏率，实验结果验证了理论计算的准确性。
【标题】Influence of input voltage on the structural and fluid flow characteristics and proposed working condition of a micro-blower
【参考中译】输入电压对微型鼓风机结构、流动特性的影响及工作条件的研究
【关键词】 Micro-blower; Piezoelectric material; Micro pump; Electronic cooling; PZT-5H; Finite element method
【参考中译】 微型鼓风机；压电材料；微型泵；电子冷却；PZT—5H；有限元法
【作者】 Velmurugan K; Bharath Sanjeevi; Adarsh Shrivastav; Chandramohan VP; Karthik Balasubramanian; Karunanidhi S
【摘要】 Several methods are explored for the thermal management of highly packed electronic systems. A forced convection setup called micro-blower is an effective solution for the application of heat removal and it consists of a piezoelectric disc (PED), diaphragm, ring and a top plate. A numerical model is developed to study the influence of input voltage on the micro-blower using COMSOL Multiphysics. The size of the micro-blower selected is 20 × 20 × 3 mm~3. Structural characteristics such as Eigen frequency, diaphragm displacement and von Mises stress and output characteristic such as velocity at the nozzle exit, the volumetric flow rate of air, density variation in the fluid domain and pressure gradient of air at the nozzle for various voltage inputs (peak-to-peak voltage, V_(p-p)) from 5 to 20 V were estimated. The diaphragm displacement of the blower was estimated with various input voltages. An average nozzle velocity of 21.21 m/s was achieved with an average volumetric flow rate of 10.66 × 10~(-6) m~3/s for the voltage input of 20 V_(p-p). The von Mises stresses of PED, diaphragm, ring and top plate were 3.38, 6.38, 15.72 and 88.97 MPa and these were within the maximum yield strength of respective components at 20 V and hence the micro-blower design is safe. The proposed Eigen frequency in the ultrasonic range was 21.298 kHz and the proposed input voltage as per the breakdown voltage was 20 V. The results were compared with existing literature data and found promising agreement.
【参考中译】 探索了几种用于高密度电子系统热管理的方法。一种被称为微型鼓风机的强制对流装置是一种有效的散热解决方案，它由压电盘(PED)、振膜、环和顶板组成。利用COMSOL多物理模型建立了输入电压对微型鼓风机影响的数值模型。所选微型鼓风机的尺寸为20×20×3 mm~3。在5~20V的不同电压输入(峰-峰电压，Vp-p)下，估算了喷嘴出口速度、空气体积流量、流体密度变化和喷嘴空气压力梯度等结构特性和输出特性。在不同输入电压下，估算了鼓风机的膜片位移。在输入电压为20Vp-p时，平均喷嘴速度为21.21m/S，平均体积流量为10.66×10-6m~3/S。PED、隔膜、环和顶板的等效应力分别为3.38、6.38、15.72和88.97 Mpa，均在20V时各部件的最大屈服强度范围内，因此微风机的设计是安全的。在超声范围内，建议的本征频率为21.298 kHz，根据击穿电压建议的输入电压为20V。将结果与现有的文献数据进行了比较，发现有希望的一致。
【来源】 Flow Measurement and Instrumentation 2023, vol.94
【标题】Study on flow separation and suction control of a compressor tandem cascade
【参考中译】压气机串联叶栅流动分离及吸入控制研究
【关键词】 Tandem cascade; Flow separation; Boundary layer suction; Blade wake; Flow control
【参考中译】 串联叶栅；流动分离；附面层抽吸；叶片尾流；流动控制
【作者】 Botao Zhang; Xiaochen Mao; Bo Liu; Hejian Wang; Zonghao Yang; Ran Zhang
【摘要】 To control the boundary layer separation on the front blade suction surface in a compressor tandem cascade at a high incidence angle, three suction schemes at different axial positions were introduced and the cascade performance improvement and separation flow control effects were investigated. Based on the experimental and numerical simulations, the aerodynamic performance of the prototype tandem cascade reaches the peak at the incidence angle of 5°. Continue to increase the incidence angle, the loss increases sharply, and the static pressure rise coefficient and diffusion factor begin to decrease. With the boundary layer suction on the suction surface of the front blade, fluid energy in the upstream boundary layer of the suction slot is increased, and the adverse pressure gradient downstream is decreased. By suction, the development and separation of the boundary layer are inhibited, and the loss in the tandem cascade is significantly reduced. The flow control effect of the suction scheme at the onset location of boundary layer separation is the best, and the flow loss can be reduced by about 34.9% with a suction flow rate of 1% at the incidence angle of 5°. The suction schemes have good flow control effects in a wide working range and broaden the available range of incidence angles of the tandem cascade. This study provides a reference for the design of tandem blades considering flow control and has a positive significance for improving compressor efficiency and pressure ratio.
【参考中译】 为了在大攻角下控制压气机串列叶栅前叶片吸力面的边界层分离，采用了3种不同轴向位置的吸气方案，研究了不同吸气方案对叶栅性能的改善和分离流动控制效果。在实验和数值模拟的基础上，原型串列叶栅的气动性能在攻角为5°时达到最大。继续增大入射角，损失急剧增加，静压升系数和扩散系数开始减小。前叶片吸力面的边界层吸力增加了吸力槽上游边界层内的流体能量，减小了下游的逆压梯度。吸力抑制了附面层的发展和分离，显著降低了串列叶栅的损失。在附面层分离开始处，吸气方案的控流效果最好，在5°入射角下，吸气流量为1%时，可使流动损失减少约34.9%。吸气方案在较宽的工作范围内具有良好的流量控制效果，拓宽了串列叶栅的攻角适用范围。该研究为考虑流量控制的串列叶片设计提供了参考，对提高压气机效率和压比具有积极意义。
【来源】 Proceedings of the Institution of Mechanical Engineers 2023, vol.237, no.23
【标题】Effect of varying ambient conditions on the performance of air conditioner using evaporative cooler
【参考中译】环境条件变化对蒸发冷却器空调性能的影响
【关键词】 Evaporative cooling; Box-Behnken design; ANOVA; COP; Sustainability index
【参考中译】 蒸发冷却；Box—Behnken设计；方差分析；COP；可持续性指数
【作者】 S. K. Gupta; B. B. Arora; A. Arora
【摘要】 The increasing usage of refrigeration and air conditioning worldwide is a serious concern as regard the greenhouse gas emissions which degrade the environment. Improving the energy efficiency could reduce this damage. The heat dissipation capacity of the condenser and performance of an air conditioner largely depend upon the temperature of the air entering the condenser. This paper evaluates the performance of a 1.5TR split air conditioner with and without evaporative cooling of condenser. The temperature reduction of the ambient air by evaporative cooling is computed for different weather conditions. The Box-Behnken design (BBD) methodology is applied to predict the interaction of parameters and optimize the results while analysis of variance (ANOVA) provides the fitness and validation of the model. It is observed that the proposed system significantly improves the performance of air conditioner. The maximum COP enhancement (9.37%) is achieved for the ambient temperature drop of 6.7℃ for the optimum operating conditions. The corresponding improvement in the refrigerating effect and savings in work input are obtained as 9.52% and 8.54%, respectively. The proposed system is estimated to pay back within 2.9 years. The sustainability indices indicate the environmental improvement by the proposed system.
【参考中译】 世界范围内越来越多的制冷和空调使用是一个令人严重关切的问题，因为温室气体排放会破坏环境。提高能源效率可以减少这种损害。冷凝器的散热能力和空调的性能在很大程度上取决于进入冷凝器的空气温度。本文对一台1.5TR型分体式空调机的冷凝器蒸发冷却和不加冷凝器的性能进行了评价。计算了不同天气条件下蒸发冷却对环境空气的降温效果。应用Box-Behnken设计(BBD)方法预测参数间的交互作用并优化结果，而方差分析(ANOVA)提供模型的适合性和有效性。结果表明，该系统显著提高了空调机的性能。在最佳运行条件下，环境温降为6.7℃时，COP提高最大(9.37%)。相应的制冷效果提高了9.52%，节省了工时8.54%。据估计，拟议的系统将在2.9年内收回成本。可持续发展指数表明了该系统对环境的改善。
【来源】 Journal of the Brazilian Society of Mechanical Sciences and Engineering 2023, vol.45, no.12
【标题】Machine Learning-Based Adaptive Fault Detection Method for Wind Turbine Gearboxes with Imbalanced Data through An IIoT Platform
【参考中译】基于机器学习的风力机齿轮箱不平衡数据自适应故障检测方法
【类型】 会议
【关键词】 Industrial internet of things (IIoT); Condition monitoring; Adaptive fault detection; Imbalanced data; Wind turbine gearbox
【参考中译】 工业物联网（IIoT）；状态监测；自适应故障检测；不平衡数据；风力涡轮机齿轮箱
【作者】 Xiao Fu; Xinnuo Li; Kuo Cao; Junyi Han
【摘要】 In the context of Industry 4.0, machine learning algorithms have been commonly used to monitor the health state of wind turbine gearboxes to avoid catastrophic failure and reduce maintenance costs. However, due to the lack of a certain category of data (i.e., healthy or faulty) and the various working conditions of wind turbines, many existing methods may not provide reliable results in practical industrial applications. To solve this problem, we create an industrial internet of things (IIoT) platform, through which a machine learning-based adaptive fault detection method for wind turbine gearboxes is proposed. The features are extracted and adapted to fine-tune the pre-trained model on newly arriving samples from different wind turbines, components, or failure modes. The adaptation performance is evaluated with accuracy, false alarm rate, and fault detection rate. Case studies are then performed using high-frequency vibration signals acquired from two megawatts (MW) onshore wind turbines. The results show that the proposed adaptive method significantly improves the fault detection performance when class distribution is not balanced, and can be easily applied to the fault diagnosis of large numbers of wind turbines. This, integrated with the IIoT platform that alleviates the shortage of computational and storage capacity in wind farms and requires less user involvement, allows for a more effective condition monitoring system.
【参考中译】 在工业4.0的背景下，机器学习算法已被普遍用于监测风电机组齿轮箱的健康状态，以避免灾难性故障，降低维护成本。然而，由于缺乏某一类数据(即健康或故障)以及风力机的各种工况，许多现有的方法在实际工业应用中可能不会提供可靠的结果。为了解决这一问题，我们创建了一个工业物联网(IIoT)平台，在此平台上提出了一种基于机器学习的风电齿轮箱自适应故障检测方法。提取特征并对其进行调整，以根据来自不同风力涡轮机、部件或故障模式的新样本来微调预先训练的模型。通过准确率、虚警率和故障检测率来评估自适应性能。然后，使用从两兆瓦陆上风力涡轮机获取的高频振动信号进行案例研究。结果表明，在类别分布不均衡的情况下，自适应方法显著提高了故障检测性能，可方便地应用于大量风电机组的故障诊断。这与IIoT平台相结合，缓解了风力发电场计算和存储能力的不足，需要更少的用户参与，从而实现了更有效的状态监测系统。
【来源】 4th International Academic Exchange Conference on Science and Technology Innovation (IAECST 2022) 4th International Academic Exchange Conference on Science and Technology Innovation (IAECST 2022)