Experimental and Numerical Investigation of Quick Closing Buffer Performance of Steam Turbine Admission Valve

2016 ◽  
Author(s):  
Lei Xiao ◽  
Sihua Xu ◽  
Jin He ◽  
Zhiqiang Hu ◽  
Xiaogang Zhou
Keyword(s):  
Numerical Simulation ◽  
Steam Turbine ◽  
Dynamic Characteristic ◽  
Impact Energy ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Buffer System ◽  
Characteristic Analysis ◽  
Cfd Numerical Simulation ◽  
The Impact

One of the main functions of the steam turbine admission valve is to provide a very fast closing to intercept the supply of mass flow rapidly from the steam entering the turbine and cause destructive overspeed. In order to quickly close the admission valve, at the beginning of the stroke the moving parts of the valve should be accelerated to a high speed; when the stroke ends, a lot of kinetic energy is converted to impact energy. To prevent damage to valve parts, a quick closing buffer system is required to absorb the most of the impact energy. The quick closing buffer system plays an important role in the admission valve as an influencing factor of the dynamic characteristics of the valve. In the past, considering the complex internal structure, the research about quick closing buffer system relied on confirmatory experimental study or analytic method to get a quick closing buffer process. This paper focus on the quick closing process of a high pressure steam admission valve of Shanghai Turbine Plant. The dynamic characteristic of the quick closing buffer system is investigated by means of method of CFD numerical simulation for the first time, in order to find a more convenient and effective way to get the key factors that affect the dynamic characteristics, and the accuracy of the of CFD numerical simulation is verified by test, which are valuable for building an accurate dynamic characteristic analysis model of steam turbine admission valve.

Study on Dynamic Pressure Effect of Gas Bearings in Fuel Cell Vehicles

2020 ◽  
Author(s):  
Chenxin Zhang ◽  
Weirong Hong ◽  
Shuiying Zheng
Keyword(s):  
Numerical Simulation ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Performance Test ◽  
Pressure Effect ◽  
Dynamic Pressure ◽  
Simulation Method ◽  
Dynamic Mesh ◽  
Gas Bearings ◽  
Cfd Numerical Simulation

Abstract The dynamic pressure effect can contribute to a better working performance of the gas bearing without changing its overall structure or increase its air supply pressure. To study the dynamic pressure effect of gas bearings, a new method of CFD numerical simulation with self-developed UDF dynamic mesh program was proposed. In this way, values of dynamic characteristics for gas bearings with different fluid fields and under different working conditions can be calculated. Based on the numerical simulation results, the influence law of rotational speed, gas film thickness, and radial eccentricity ratio on the dynamic characteristics (load-carrying capacity, stiffness and damping coefficients, static equilibrium position etc.) were obtained. Afterwards, a bearing’s performance test was conducted on a rotor-bearing system in the high-speed air compressor. Compared to the traditional methods, after the dynamic pressure effect was taken into account, the corresponding rotor dynamic calculation of critical speed is more in accordance with the experimental results, thus proved the credibility of the new CFD numerical simulation method with dynamic mesh.

scholarly journals Numerical simulation and experimental research of cavitation nozzle based on equation curve

2021 ◽  
Author(s):  
Lifu Wang ◽  
Dongyan Shi ◽  
Zhixun Yang ◽  
Guangliang Li ◽  
Chunlong Ma ◽  
...  
Keyword(s):  
Numerical Simulation ◽  
Reynolds Number ◽  
Flow Field ◽  
High Speed ◽  
Quadratic Equation ◽  
Outer Contour ◽  
Study Results ◽  
Fluent Software ◽  
The Impact ◽  
Better Than

Abstract To further investigate and improve the cleaning ability of the cavitation nozzle, this paper proposes a new model that is based on the Helmholtz nozzle and with the quadratic equation curve as the outer contour of the cavitation chamber. First, the numerical simulation of the flow field in the nozzle chamber was conducted using FLUENT software to analyze and compare the impact of the curve parameters and Reynolds number on the cleaning effect. Next, the flow field was captured by a high-speed camera in order to study the cavitation cycle and evolution process. Then, experiments were performed to compare the cleaning effect of the new nozzle with that of the Helmholtz nozzle. The study results demonstrate that effective cavitation does not occur when the diameter of the cavitation chamber is too large. For the new nozzle, with the increase of the Reynolds number, the degree of cavitation in the chamber first increases and then decreases; the cleaning effect is much better than that of a traditional Helmholtz nozzle under the same conditions; the nozzle has the best cleaning effect for the stand-off distance of 300 mm.

Research on Fault Diagnosis of Steam Turbine Rotor Unbalance and Parallel Misalignment Based on Numerical Simulation and Convolutional Neural Network

2021 ◽  
Author(s):  
Chongyu Wang ◽  
Di Zhang ◽  
Yonghui Xie
Keyword(s):  
Neural Network ◽  
Numerical Simulation ◽  
Fault Detection ◽  
Steam Turbine ◽  
Turbine Rotor ◽  
Detection Accuracy ◽  
Steam Turbine Rotor ◽  
Parallel Misalignment ◽  
Coupling Fault ◽  
The Impact

Abstract The steam turbine rotor is still the main power generation equipment. Affected by the impact of new energy on the power grid, the steam turbine needs to participate in peak load regulation, which will make turbine rotor components more prone to failure. The rotor is an important equipment of a steam turbine. Unbalance and misalignment are the normal state of rotor failure. In recent years, more and more attention has been paid to the fault detection method based on deep learning, which takes rotating machinery as the object. However, there is a lack of research on actual steam turbine rotors. In this paper, a method of rotor unbalance and parallel misalignment fault detection based on residual network is proposed, which realizes the end-to-end fault detection of rotor. Meanwhile, the method is evaluated with numerical simulation data, and the multi task detection of rotor unbalance, parallel misalignment, unbalanced parallel misalignment coupling faults (coupling fault called in this paper) is realized. The influence of signal-to-noise ratio and the number of training samples on the detection performance of neural network is discussed. The detection accuracy of unbalanced position is 93.5%, that of parallel misalignment is 99.1%. The detection accuracy for unbalance and parallel misalignment is 89.1% and 99.1%, respectively. The method can realize the direct mapping between the unbalanced, parallel misalignment, coupling fault vibration signals and the fault detection results. The method has the ability to automatically extract fault features. It overcomes the shortcoming of traditional methods that rely on signal processing experience, and has the characteristics of high precision and strong robustness.

scholarly journals Finite Element Analysis of Impact Energy on Spur Gear

2018 ◽  
Vol 225 ◽  
pp. 06011 ◽  
Author(s):  
Ismail Ali Bin Abdul Aziz ◽  
Daing Mohamad Nafiz Bin Daing Idris ◽  
Mohd Hasnun Arif Bin Hassan ◽  
Mohamad Firdaus Bin Basrawi
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Impact Energy ◽  
High Speed ◽  
Impact Test ◽  
Impact Load ◽  
Gear Tooth ◽  
Test Equipment ◽  
Element Analysis ◽  
The Impact

In high-speed gear drive and power transmission, system impact failure mode always occurs due to the sudden impact and shock loading during the system in running. Therefore, study on the amount of impact energy that can be absorbed by a gear is vital. Impact test equipment has been designed and modelled for the purpose to study the impact energy on gear tooth. This paper mainly focused on Finite Element Analysis (FEA) of impact energy that occurred during simulation involving the impact test equipment modelling. The simulation was conducted using Abaqus software on critical parts of the test equipment to simulate the impact event and generate impact data for analysis. The load cell in the model was assumed to be free fall at a certain height which gives impact load to the test gear. Three different type of material for the test gear were set up in this simulation. Results from the simulation show that each material possesses different impact energy characteristic. Impact energy values increased along with the height of load drop. AISI 1040 were found to be the toughest material at 3.0m drop that could withstand up to 44.87N.m of impact energy. These data will be used to validate data in physical experiments in further study.

scholarly journals Dynamic characteristic analysis of a high-speed small piezoelectric turntable

2019 ◽  
Vol 612 ◽  
pp. 032093
Author(s):  
Shan Xue ◽  
Jianbo Guo ◽  
Zhengbin Liu ◽  
Guangqing Li ◽  
Qiongying Lv
Keyword(s):  
Dynamic Characteristic ◽  
High Speed ◽  
Characteristic Analysis

The Double Pendulum Model and Nonlinear Dynamic Characteristics of the Pantograph of High-Speed Train

2013 ◽  
Vol 275-277 ◽  
pp. 767-770
Author(s):  
Hua Li ◽  
Shu Qian Cao
Keyword(s):  
Numerical Simulation ◽  
Dynamic Characteristics ◽  
High Speed ◽  
Lagrange Equation ◽  
Variable Stiffness ◽  
Nonlinear Damping ◽  
Double Pendulum ◽  
High Speed Train ◽  
Pendulum Model ◽  
Damping Torque

In this paper, the double pendulum model of the pantograph was developed, in which a square angular velocity damping torque was used to describe the nonlinear damping torque of the hydraulic vibration damper, and the catenary was described as a variable stiffness spring. Considering the nonlinear factors caused by hydraulic damping and the interaction between the catenary and the pantograph, the motion differential equations based on the double pendulum model were established in Lagrange equation, and then were simplified. The dynamic characteristics were analyzed through numerical simulation. The result of numerical simulation shows that there are quasi-periodic motion and chaos in the system, which are both affected by the pendulum length ratio. The results are helpful to research the dynamic characteristics of the pantograph of high-speed train.

The Dynamic Characteristic Analysis of Full Hydraulic Steering System in Large Mining Truck

2013 ◽  
Vol 433-435 ◽  
pp. 59-62
Author(s):  
Jiang Yong
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Characteristics ◽  
Steering System ◽  
Technical Support ◽  
Heavy Duty ◽  
Characteristic Analysis ◽  
Hydraulic Steering

The SGA170 mine truck was used as research object, the full hydraulic steering system and it's dynamic characteristics was simulated by the AMESim, the characteristics and simulation curve of the steering system and the steering mechanical under various conditions was obtained, which provided theoretical reference and technical support to the design and analysis of full hydraulic steering system of the heavy-duty mine truck, and has important value in the engineering.

Impact Energy Measurement of a Hydraulic Breaker

2006 ◽  
Vol 326-328 ◽  
pp. 1669-1672
Author(s):  
Jong Won Park ◽  
Hyoung Eui Kim
Keyword(s):  
Construction Industry ◽  
Impact Energy ◽  
High Speed ◽  
Test System ◽  
Hydraulic Power ◽  
Construction Machinery ◽  
Road Pavement ◽  
Hydraulic Cylinders ◽  
The Impact ◽  
Test Process

A hydraulic breaker for construction machinery generally used for the destroying and disassembling of buildings, crashing road pavement, breaking rocks at quarry and so on. So the measurement of the impact energy of a hydraulic breaker is very important thing to prove its capability to manufacturers and customers. In this study, the test system for measuring the impact energy of a hydraulic breaker was designed and constructed. The test system was consisted with hydraulic cylinders for mounting a breaker, impact absorbing base and frames, pressure and flow sensors, high speed and accurate data acquisition system diesel engine driven hydraulic power unit. The test process of the developed system was carried by measuring guide for tool energy rating for hydraulic breakers which was developed by the CIMA (Construction Industry Manufacturers Association) USA. The developed test system can be applied to measure the impact energy for various kinds of hydraulic breakers.

Study on the Downburst Field Characteristics under the Influence of Two-Dimensional Continuous Mountains at Different Distance

2014 ◽  
Vol 580-583 ◽  
pp. 3111-3114
Author(s):  
Yi Sun ◽  
Yuan Ze Wu ◽  
Hai Tao Shi ◽  
Bai Feng Ji
Keyword(s):  
Numerical Simulation ◽  
Boundary Layer ◽  
Wind Field ◽  
Strong Wind ◽  
Two Dimensional ◽  
Field Characteristic ◽  
Main Factors ◽  
Cfd Numerical Simulation ◽  
The Impact

Downburst is an outburst strong wind on or near the ground, and its wind field characteristics are significantly different from boundary layer winds. Continuous mountains at different distance are one of the main factors for the influence of downburst wind field characteristic. In this thesis, the changes of the wind field characteristics under the influence of continuous mountains at different distance after the downburst happened are studied by CFD numerical simulation. The impact of downburst is analysed and summarized through the charts.

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