scholarly journals Numerical Modeling and Experimental Verification for High-Speed and Heavy-Load Planar Mechanism with Multiple Clearances

2015 ◽  
Vol 2015 ◽  
pp. 1-11 ◽  
Author(s):  
Fangang Meng ◽  
Shijing Wu ◽  
Fan Zhang ◽  
Liang Liang
Keyword(s):  
High Speed ◽  
Circuit Breaker ◽  
Fast Response ◽  
Transmission Mechanism ◽  
Heavy Load ◽  
Clearance Joints ◽  
Moving Contact ◽  
Center Path ◽  
The Impact ◽  
Impact Motion

Transmission mechanism is one of the most important parts of the Ultra-High Voltage (UHV) circuit breaker. It has specific characteristics such as fast response, high speed, and heavy load in the processes of open and close actions. This paper studies the effects of multiple clearances on the working characteristics of transmission mechanism system, especially the motion of its journal center path during operation. It builds a nonlinear kinetic model of transmission mechanism considering the system energy losses due to the impact and friction between the journal and bearing inside clearance joints. Also, an experimental platform is built to measure the displacement and velocity of the moving contact. The results show that the existence of 15 clearance joints in our mechanism system can cause hysteresis effects on the velocity and acceleration of the moving contact, as well as its acceleration fluctuation. Meanwhile, the increase of friction coefficient will stabilize the dynamic characteristic. In addition, both the experimental and simulation results indicate that the motion of the journal center, which is unevenly distributed along the circle, is characterized by three phases: free flight motion, contact motion, and impact motion.

Compound sliding-mode predictive control for a temperature system of high-speed heat-airflow wind tunnel

2013 ◽  
Vol 228 (11) ◽  
pp. 1869-1879 ◽  
Author(s):  
Chaozhi Cai ◽  
Yunhua Li ◽  
Sujun Dong
Keyword(s):  
Wind Speed ◽  
High Speed ◽  
Sliding Mode ◽  
Fast Response ◽  
Feedback Controller ◽  
Compound Control ◽  
The Impact ◽  
The Mathematical Model ◽  
Valve Control ◽  
Ramp Signal

The mathematical model of the temperature system under the mode of the proportional throttle valve control and the variable frequency pump control is established, respectively. A compound control strategy that consists of a compensation controller and a sliding-mode predictive feedback controller is designed. The compensation controller, which takes the change of the wind speed as parameter, is used to eliminate the impact on the system caused by the change of the working conditions (wind speed); the sliding-mode predictive feedback controller is used to solve the problems in the system such as time delay, time-varying parameters and disturbance. In order to solve the problem of temperature disturbance caused by the mode switch between pump control and valve control and the oil-rich combustion phenomenon in the high-temperature case, a method takes the ramp signal in which the slope is adjustable as a temperature setting signal is proposed. The experimental results show that the designed strategy obtains a satisfactory control performance and can achieve the temperature control with fast response time and no overshoot. In addition, it takes the ramp signal in which the slope is adjustable as the temperature setting signal can achieve the undisturbed switching control of the temperature and prevent the oil-rich combustion effectively.

Multi-Body Impact Motion With Friction: Analysis, Simulation, and Experimental Validation

1990 ◽  
Author(s):  
Inhwan Han ◽  
B. J. Gilmore
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Impact Dynamics ◽  
Body System ◽  
High Speed Video Camera ◽  
Multi Body ◽  
The Impact ◽  
Friction Analysis ◽  
Impact Motion

Abstract When a multi-body system collides with a single body or with another multi-body system, impact dynamics with friction should be considered. This paper presents a general computer oriented analysis of impact dynamics incorporating friction. The presence of friction between sliding contacts during the impact makes the problem difficult since the events such as reverse sliding or sticking, which may occur at different times throughout the impact, must be determined. The boundary representations of the bodies are used to solve for the velocities at the points of contact. Using this information and a classification of the modes of impact, the frictional impact with sliding contact problem is solved. Using a high speed video camera, the resulting computer strategy is experimentally verified. Simulation and experimental results agree.

Experimental and Numerical Investigation of the Unsteady Flow Field in a Vaned Diffuser of a High-Speed Centrifugal Compressor

2015 ◽  
Vol 137 (7) ◽  
Author(s):  
Klemens Vogel ◽  
Reza S. Abhari ◽  
Armin Zemp
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Fast Response ◽  
Operating Conditions ◽  
Wake Flow ◽  
Vaned Diffuser ◽  
Wide Range ◽  
The Impact

Vaned diffusers in centrifugal compressor stages are used to achieve higher stage pressure ratios, higher stage efficiencies, and more compact designs. The interaction of the stationary diffuser with the impeller can lead to resonant vibration with potentially devastating effects. This paper presents unsteady diffuser vane surface pressure measurements using in-house developed, flush mounted, fast response piezoresistive pressure transducers. The unsteady pressures were recorded for nine operating conditions, covering a wide range of the compressor map. Experimental work was complemented by 3D unsteady computational fluid dynamics (CFD) simulations using ansys cfx V12.1 to detail the unsteady diffuser aerodynamics. Pressure fluctuations of up to 34.4% of the inlet pressure were found. High pressure variations are present all along the vane and are not restricted to the leading edge region. Frequency analysis of the measured vane surface pressures show that reduced impeller loading, and the corresponding reduction of tip leakage fluid changes the characteristics of the fluctuations from a main blade count to a total blade count. The unsteady pressure fluctuations in the diffuser originate from three distinct locations. The impact of the jet-wake flow leaving the impeller results in high variation close to the leading edge. It was observed that CFD results overpredicted the amplitude of the pressure fluctuation on average by 62%.

Multi-Body Impact Motion with Friction—Analysis, Simulation, and Experimental Validation

1993 ◽  
Vol 115 (3) ◽  
pp. 412-422 ◽  
Author(s):  
Inhwan Han ◽  
B. J. Gilmore
Keyword(s):  
High Speed ◽  
Video Camera ◽  
Impact Dynamics ◽  
Body System ◽  
High Speed Video Camera ◽  
Multi Body ◽  
The Impact ◽  
Friction Analysis ◽  
Impact Motion

When a multi-body system collides with a single body or with another multi-body system, impact dynamics with friction should be considered. This paper presents a general computer oriented analysis of impact dynamics incorporating friction. The presence of friction between sliding contacts during the impact makes the problem difficult since the events such as reverse sliding or sticking, which may occur at different times throughout the impact, must be determined. The boundary representations of the bodies are used to solve for the velocities at the points of contact. Using this information and a classification of the modes of impact, the frictional impact with sliding contact problem is solved. Using a high speed video camera, the resulting computer strategy is experimentally verified. Simulation and experimental results agree.

Experimental and Numerical Investigation of the Unsteady Flow Field in a Vaned Diffuser of a High-Speed Centrifugal Compressor

2014 ◽  
Author(s):  
Klemens Vogel ◽  
Reza S. Abhari ◽  
Armin Zemp
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Fluctuations ◽  
Leading Edge ◽  
Fast Response ◽  
Operating Conditions ◽  
Wake Flow ◽  
Vaned Diffuser ◽  
Wide Range ◽  
The Impact

Vaned diffusers in centrifugal compressor stages are used to achieve higher stage pressure ratios, higher stage efficiencies and more compact designs. The interaction of the stationary diffuser with the impeller can lead to resonant vibration with potentially devastating effects. This paper presents unsteady diffuser vane surface pressure measurements using in-house developed, flush mounted, fast response piezo-resistive pressure transducers. The unsteady pressures were recorded for 9 operating conditions, covering a wide range of the compressor map. Experimental work was complemented by 3D unsteady CFD simulations using ANSYS CFX V12.1 to detail the unsteady diffuser aerodynamics. Pressure fluctuations of up to 34.4% of the inlet pressure were found. High pressure variations are present all along the vane and are not restricted to the leading edge region. Frequency analysis of the measured vane surface pressures show that reduced impeller loading and the corresponding reduction of tip leakage fluid changes the characteristics of the fluctuations from a main blade count to a total blade count. The unsteady pressure fluctuations in the diffuser originate from three distinct locations. The impact of the jet wake flow leaving the impeller results in high variation close to the leading edge. It was observed that CFD results overpredicted the amplitude of the pressure fluctuation on average by 62%.

scholarly journals Modeling and Simulation of Flexible Transmission Mechanism with Multiclearance Joints for Ultrahigh Voltage Circuit Breakers

2015 ◽  
Vol 2015 ◽  
pp. 1-17 ◽  
Author(s):  
Fangang Meng ◽  
Shijing Wu ◽  
Fan Zhang ◽  
Zenglei Zhang ◽  
Jicai Hu ◽  
...  
Keyword(s):  
Dynamic Characteristics ◽  
High Reliability ◽  
Circuit Breaker ◽  
Principal Component ◽  
Dynamic Contact ◽  
Coupling Model ◽  
Transmission Mechanism ◽  
Vector Model ◽  
Clearance Joints ◽  
Adams Software

The transmission mechanism, of which the dynamic characteristics determine the reliability of the circuit breaker, is the principal component of the ultrahigh voltage (UHV) circuit breaker. The characteristics of transmission mechanism are quick motion, high sensibility, and high reliability. The transmission mechanism with multiclearance joints present strong no-linear vibration feature which strongly affects the reliability of the UHV circuit breaker. In this investigation, a planar rigid-flexible coupling model of the transmission mechanism considering the clearance joints and the flexibility of components is established by using ADAMS software. The dynamic contact model in clearance joints is performed, based on clearance vector model of clearance joint. Then, the reliability of the model is proved by means of comparing the results of experiments. The simulation results show that the dynamic response of the mechanism is greatly influenced by the clearance and the flexibility of components has a role of suspension for the mechanism. Moreover, the influence of the clearance size, input speed, and number of clearance joints on the dynamic characteristics of the mechanism are also investigated.

Modeling of Tread Block Contact Mechanics Using Linear Viscoelastic Theory3

2008 ◽  
Vol 36 (3) ◽  
pp. 211-226 ◽  
Author(s):  
F. Liu ◽  
M. P. F. Sutcliffe ◽  
W. R. Graham
Keyword(s):  
High Speed ◽  
Slip Rate ◽  
Material Model ◽  
Contact Forces ◽  
Block Modeling ◽  
Rate Dependent ◽  
Linear Viscoelastic Material ◽  
Linear Viscoelastic ◽  
The Impact ◽  
Good Agreement

Abstract In an effort to understand the dynamic hub forces on road vehicles, an advanced free-rolling tire-model is being developed in which the tread blocks and tire belt are modeled separately. This paper presents the interim results for the tread block modeling. The finite element code ABAQUS/Explicit is used to predict the contact forces on the tread blocks based on a linear viscoelastic material model. Special attention is paid to investigating the forces on the tread blocks during the impact and release motions. A pressure and slip-rate-dependent frictional law is applied in the analysis. A simplified numerical model is also proposed where the tread blocks are discretized into linear viscoelastic spring elements. The results from both models are validated via experiments in a high-speed rolling test rig and found to be in good agreement.

Direct Current Deadbeat Predictive Controller for BLDC Motor Using Single DC-Link Current Sensor

2020 ◽  
Vol 38 (8A) ◽  
pp. 1187-1199
Author(s):  
Qaed M. Ali ◽  
Mohammed M. Ezzalden
Keyword(s):  
Control System ◽  
High Speed ◽  
Fast Response ◽  
Bldc Motor ◽  
Current Controller ◽  
Three Phase ◽  
Predictive Controller ◽  
Two Phases ◽  
Dc Current ◽  
Three Phase Inverter

BLDC motors are characterized by electronic commutation, which is performed by using an electric three-phase inverter. The direct control system of the BLDC motor consists of double loops; including the inner-loop for current regulating and outer-loop for speed control. The operation of the current controller requires feedback of motor currents; the conventional current controller uses two current sensors on the ac side of the inverter to measure the currents of two phases, while the third current would be accordingly calculated. These two sensors should have the same characteristics, to achieve balanced current measurements. It should be noted that the sensitivity of these sensors changes with time. In the case of one sensor fails, both of them must be replaced. To overcome this problem, it is preferable to use one sensor instead of two. The proposed control system is based on a deadbeat predictive controller, which is used to regulate the DC current of the BLDC motor. Such a controller can be considered as digital controller mode, which has fast response, high precision and can be easily implemented with microprocessor. The proposed control system has been simulated using Matlab software, and the system is tested at a different operating condition such as low speed and high speed.

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