Adaptive Vaned Diffuser for Centrifugal Compressor

2005 ◽  
Author(s):  
G. Ferrara ◽  
L. Ferrari ◽  
L. Baldassarre
Keyword(s):  
Centrifugal Compressor ◽  
High Efficiency ◽  
Flow Coefficient ◽  
Maximum Efficiency ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Loop Control ◽  
Loop Control System ◽  
Actual Flow ◽  
Close Loop Control

Vaned diffusers are often preferred to a vaneless solution for improving maximum efficiency. The drawbacks of this choice are the reduction of stable working range and a narrower flow coefficient range at high efficiency. In this paper a solution to the above mentioned problems is presented. The solution proposed involves an adaptive vaned diffuser: the vanes can be oriented in order to find the optimum incidence by means of a mechanism moved by an oleo-dynamic piston. Several sensor typologies have been tested to find which is the best to assess the actual flow angle. The aim is to correlate the optimum vane position with sensor output in order to provide a close-loop control system. An experimental analysis was carried out on an intermediate centrifugal compressor stage to validate this approach.

Steady and Transient Computations of Interaction Effects in a Centrifugal Compressor With Different Types of Diffusers

2010 ◽  
Author(s):  
S. Anish ◽  
N. Sitaram
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Leading Edge ◽  
Design Flow ◽  
Flow Coefficient ◽  
Pressure Recovery ◽  
Maximum Efficiency ◽  
Vaned Diffuser ◽  
Lower Flow ◽  
Transient Simulations

A computational study has been conducted to analyze the performance of a centrifugal compressor under various levels of impeller-diffuser interactions. The study has been conducted using a low solidity vaned diffuser (LSVD), a conventional vaned diffuser (VD) and a vaneless diffuser (VLD). The study is carried out using Reynolds-Averaged Navier-Stokes simulations. A commercial software ANSYS CFX is used for this purpose. The intensity of interaction is varied by keeping the diffuser vane leading edge at three different radial locations. Frozen rotor and transient simulations are carried out at four different flow coefficients. At design flow coefficient maximum efficiency occurs when the leading edge is at R3 (ratio of radius of the diffuser leading edge to the impeller tip radius) = 1.10. At lower flow coefficient higher stage efficiency occurs when the diffuser vanes are kept at R3 = 1.15 and at higher flow coefficient R3 = 1.05 gives better efficiency. It is observed that at lower flow coefficients positive incidence causes separation of flow at the suction side of the diffuser vane. When the flow rate is above design point there is a negative incidence at the leading edge of the diffuser vane which causes separation of flow from the pressure side of the diffuser vane. Compressor stage performance as well as performance of individual components is calculated at different time steps. Large variations in the stage performances at off-design flow coefficients are observed. The static pressure recovery coefficient (Cp) value is found to be varying with the relative position of impeller and diffuser. It is observed that maximum Cp value occurred at time step where Ψloss value is lowest. From the transient simulations it has been found that the strength and location of impeller exit wake affect the diffuser vane loading which in turn influences the diffuser static pressure recovery.

An Efficient Approach for Modeling and Control of a Quadrotor

2016 ◽  
Vol 4 (2) ◽  
pp. 1-16
Author(s):  
Ahmed S. Khusheef
Keyword(s):  
Pid Control ◽  
Control Method ◽  
Mechanical Design ◽  
Loop Control ◽  
Modeling And Control ◽  
Loop Control System ◽  
And Control ◽  
Close Loop Control ◽  
Close Loop Control System ◽  
Made In

 A quadrotor is a four-rotor aircraft capable of vertical take-off and landing, hovering, forward flight, and having great maneuverability. Its platform can be made in a small size make it convenient for indoor applications as well as for outdoor uses. In model there are four input forces that are essentially the thrust provided by each propeller attached to each motor with a fixed angle. The quadrotor is basically considered an unstable system because of the aerodynamic effects; consequently, a close-loop control system is required to achieve stability and autonomy. Such system must enable the quadrotor to reach the desired attitude as fast as possible without any steady state error. In this paper, an optimal controller is designed based on a Proportional Integral Derivative (PID) control method to obtain stability in flying the quadrotor. The dynamic model of this vehicle will be also explained by using Euler-Newton method. The mechanical design was performed along with the design of the controlling algorithm. Matlab Simulink was used to test and analyze the performance of the proposed control strategy. The experimental results on the quadrotor demonstrated the effectiveness of the methodology used.

Surge in a Low-Speed Radial Compressor

1998 ◽  
Author(s):  
Corine Meuleman ◽  
Frank Willems ◽  
Rick de Lange ◽  
Bram de Jager
Keyword(s):  
Flow Rate ◽  
Pressure Rise ◽  
Flow Coefficient ◽  
Lumped Parameter Model ◽  
Pressure Oscillations ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Radial Compressor ◽  
Low Speed ◽  
Lumped Parameter

Surge is measured in a low-speed radial compressor with a vaned diffuser. For this system, the flow coefficient at surge is determined. This coefficient is a measure for the inducer inlet flow angle and is found to increase with increasing rotational speed. Moreover, the frequency and amplitude of the pressure oscillations during fully-developed surge are compared with results obtained with the Greitzer lumped parameter model. The measured surge frequency increases when the compressor mass flow is throttled to a smaller flow rate. Simulations show that the Greitzer model describes this relation reasonably well except for low rotational speeds. The predicted amplitude of the pressure rise oscillations is approximately two times too small when deep surge is met in the simulations. For classic surge, the agreement is worse. The amplitude is found to depend strongly on the shape of the compressor and throttle characteristic, which are not accurately known.

Responses and Optimization of a PID-Based Speed Regulating System of the Planetary Mixer

2011 ◽  
Vol 418-420 ◽  
pp. 1865-1868
Author(s):  
Ming Jin Yang ◽  
Xi Wen Li ◽  
Zhi Gang Wang ◽  
Tie Lin Shi
Keyword(s):  
Control System ◽  
Open Loop ◽  
Open Loop Control ◽  
Efficient Operation ◽  
Loop Control ◽  
Loop Control System ◽  
Response Optimization ◽  
Close Loop Control ◽  
Close Loop Control System

The performance of speed regulating is very important to the mixing process with safe, efficient operation and high quality of production. Strategies and practices of responses and optimization of a PID-based speed regulating system of a planetary mixer were presented in this paper. Research results show that: by means of the signal constraint function presented by Simulink Response Optimization, optimization PID parameters of the 2-DOF-PID controller can be obtained, and the response of close-loop control system has quite good performance of overshoot, response time, and stability compared with an open-loop control system.

Some Studies on Low Solidity Vaned Diffusers of a Centrifugal Compressor Stage

2005 ◽  
Author(s):  
T. Ch. Siva Reddy ◽  
G. V. Ramana Murty ◽  
Prasad Mukkavilli ◽  
D. N. Reddy
Keyword(s):  
Centrifugal Compressor ◽  
Static Pressure ◽  
Pressure Ratio ◽  
Pressure Recovery ◽  
Compressor Stage ◽  
Recovery Coefficient ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Centrifugal Compressor Stage ◽  
Pressure Recovery Coefficient

Numerical simulation of impeller and low solidity vaned diffuser (LSD) of a centrifugal compressor stage is performed individually using CFX- BladeGen and BladeGenPlus codes. The tip mach number for the chosen study was 0.35. The same configuration was used for experimental investigation for a comparative study. The LSD vane is formed using standard NACA profile with marginal modification at trailing edge. The performance parameters obtained form numerical studies at the exit of impeller and the diffuser have been compared with the corresponding experimental data. These parameters are pressure ratio, polytropic efficiency and flow angle at the impeller exit where as the parameters those have been compared at the exit of diffuser are the static pressure recovery coefficient and the exit flow angle. In addition, the numerical prediction of the blade loading in terms of blade surface pressure distribution on LSD vane has been compared with the corresponding experimental results. Static pressure recovery coefficient and flow angle at diffuser exit is seen to match closely at higher flows. The difference at lower flows could be due to the effect of interaction between impeller and diffuser combinations, as the numerical analysis was done separately for impeller and diffuser and the effect of impeller diffuser interaction was not considered.

Modeling and Simulation of Brushless DC Motor Adaptive Fuzzy PID Control System for Pure Electric Vehicle

2012 ◽  
Vol 466-467 ◽  
pp. 1339-1343 ◽  
Author(s):  
Shu Song ◽  
Ya Jun Zhang
Keyword(s):  
Control System ◽  
Linear Systems ◽  
Mathematic Model ◽  
Fuzzy Pid ◽  
Fuzzy Pid Control ◽  
Loop Control ◽  
Adaptive Fuzzy ◽  
Loop Control System ◽  
Close Loop Control ◽  
Close Loop Control System

Pure Electric Vehicles (PEV) is an important research direction to solve the problems of auto environment and energy sources. Research double close-loop control system of PEV driven by Brushless Direct Current Motor (BLDCM) has the practical value. Traditional PID controllers have some advantages of being simple, reliable and effective for linear systems, but not for time-varying systems or highly non-linear systems. In order to improve the performances in both steady state and transient state of control system, an Adaptive Fuzzy PID Controller (AFPIDC) can be employed. The dynamic model of PEV and the mathematic model of BLDCM can be analyzed and established. Simulation model of Speed and Current Double Close-Loop Control System are implemented by Matlab7.0/simulink. The simulation results show that the system has rapid response, without static error and overshoot, good performance and strong robustness, high capacity of resisting disturbance.

A New Stabilizing Controller Design Based on the Wireless Networked Control System

2013 ◽  
Vol 331 ◽  
pp. 294-298
Author(s):  
Xiao Hua Guo
Keyword(s):  
Control System ◽  
Controller Design ◽  
Networked Control System ◽  
Network Control ◽  
Linear Matrix ◽  
Stabilizing Controller ◽  
Loop Control ◽  
Time Varying Delay ◽  
Loop Control System ◽  
Close Loop Control

In order to improve the performance of the network control system based on the wireless sensor networks, a multi-hopping wireless communication and their effect on network time-varying delay is analyzed, and a new stabilizing controller is proposed based on the a clientserver model in this paper. Using of the linear matrix inequality and switched control system theory to obtain the stabilizing conditions of the close loop control system and give the output feedback controller design approach. Preliminary experimentation indicates the rationality and effectiveness of the proposed control algorithm.

Off-Design Flow Measurements in a Centrifugal Compressor Vaneless Diffuser

1995 ◽  
Vol 117 (4) ◽  
pp. 602-608 ◽  
Author(s):  
A. Pinarbasi ◽  
M. W. Johnson
Keyword(s):  
Flow Rate ◽  
Centrifugal Compressor ◽  
Secondary Flows ◽  
Design Flow ◽  
Vaneless Diffuser ◽  
Flow Measurements ◽  
Vaned Diffuser ◽  
Flow Angle ◽  
Flow Rates ◽  
Study Results

Detailed measurements have been taken of the three-dimensional velocity field within the vaneless diffuser of a backswept low speed centrifugal compressor using hot-wire anemometry. A 16 percent below and an 11 percent above design flow rate were used in the present study. Results at both flow rates show how the blade wake mixes out more rapidly than the passage wake. Strong secondary flows inherited from the impeller at the higher flow rate delay the mixing out of the circumferential velocity variations, but at both flow rates these circumferential variations are negligible at the last measurement station. The measured tangential/radial flow angle is used to recommend optimum values for the vaneless space and vane angle for design of a vaned diffuser.

Simulation Study on Travel-Driven System of HST Loader with Matlab/Simulink

2013 ◽  
Vol 313-314 ◽  
pp. 1100-1104
Author(s):  
En Zhe Song ◽  
Chang Xi Ji ◽  
Mei Liang Yin ◽  
Jun Sun ◽  
Cheng Shun Yin
Keyword(s):  
Pid Control ◽  
Theoretical Basis ◽  
Control Algorithm ◽  
High Efficiency ◽  
Practical Significance ◽  
Matlab Simulink ◽  
Loop Control ◽  
Driven System ◽  
Close Loop Control ◽  
The Mathematical Model

This paper establishes the mathematical model of the volume speed-modulating system and simulates dynamically with Matlab/Simulink. Provide a theoretical basis for algorithm of close loop control [ of the three variables which are diesel engines, variable pump and variable motor. Use PID control algorithm, through simulation and analysis, find out the parameter optimization adjustment rule [2,, seek matching operation between three variables. Provide a theoretical basis for the study on dynamic system of full-hydraulic loaders and have very important practical significance in realizing high efficiency energy saving and reducing energy consumption.

Energy Based Characterization of Fatigue Behaviour of Cyclically Unstable Materials

2009 ◽  
Vol 147-149 ◽  
pp. 512-517 ◽  
Author(s):  
Ewald Macha ◽  
Jacek Slowik ◽  
Roland Pawliczek
Keyword(s):  
Control System ◽  
Laboratory Tests ◽  
Fatigue Behaviour ◽  
Loop Control ◽  
New Energy ◽  
Loop Control System ◽  
Definition Of ◽  
Close Loop Control ◽  
Close Loop Control System

The paper presents a definition of a new energy based parameter which allows to better describe fatigue proprieties of materials, especially cyclically unstable materials in comparison with the Lagoda-Macha parameter. The proposed parameter distinguishes positive and negative work of external force and depends on the sign of the stresses in paths of strain in materials. It is used in laboratory tests for control of a fatigue process on hydraulic stand. A close-loop control system has been equipped with computer program based on MATLAB/Simulink module.

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