rotor speed
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2022 ◽  
Vol 12 (2) ◽  
pp. 744
Author(s):  
Xinglong Zhang ◽  
Lingwei Li ◽  
Tianhong Zhang

The main data source for the verification of surge detection methods still rely on test rigs of the compressor or the whole engine, which makes the development of models of the whole engine surge process an urgent need to replace the high-cost and high-risk surge test. In this paper, a novel real-time surge model based on the surge mechanism is proposed. Firstly, the turboshaft engine component level model (CLM) and the classic surge dynamic model, Moore-Greitzer (MG) model is established. Then the stability of the MG model is analyzed and the compressor characteristics in the classical MG model are extended to establish the extended MG model. Finally, this paper considers the coupling relationship of the compressor’s rotor speed, mass flow and pressure between CLM and the extended MG model to establish the real-time model of the turboshaft engine with surge process. The simulation results show that this model can realize the whole surge process of the turboshaft engine under multiple operating states. The change characteristics of the rotor speed, compressor outlet pressure, mass flow, exhaust gas temperature and other parameters are consistent with the test data, which means that the model proposed can be further applied to the research of surge detection and anti-surge control.


Author(s):  
Sina Ameli ◽  
Olugbenga Anubi

Abstract This paper solves the problem of regulating the rotor speed tracking error for wind turbines in the full-load region by an effective robust-adaptive control strategy. The developed controller compensates for the uncertainty in the control input effectiveness caused by a pitch actuator fault, unmeasurable wind disturbance, and nonlinearity in the model. Wind turbines have multi-layer structures such that the high-level structure is nonlinearly coupled through an aggregation of the low-level control authorities. Hence, the control design is divided into two stages. First, an ℒ2 controller is designed to attenuate the influence of wind disturbance fluctuations on the rotor speed. Then, in the low-level layer, a controller is designed using a proposed adaptation mechanism to compensate for actuator faults. The theoretical results show that the closed-loop equilibrium point of the regulated rotor speed tracking error dynamics in the high level is finite-gain ℒ2 stable, and the closed-loop error dynamics in the low level is globally asymptotically stable. Simulation results show that the developed controller significantly reduces the root-mean- square of the rotor speed error compared to some well-known works, despite the largely fluctuating wind disturbance, and the time-varying uncertainty in the control input effectiveness.


Machines ◽  
2022 ◽  
Vol 10 (1) ◽  
pp. 39
Author(s):  
Xin Xiong ◽  
Yanfei Zhou ◽  
Yiqun Wang

Many randomly uncertain factors inevitably arise when gas flows through a labyrinth seal, and the orbit of the rotor center will not rotate along a steady trajectory, as previously studied. Here, random uncertainty is considered in an interlocking labyrinth seal-rotor system to investigate the fluctuations of dynamic coefficients. The bounded noise excitation is introduced into the momentum equation of the gas flow, and as a result, the orbit of the rotor center is expressed as the combination of an elliptic trajectory with the bounded noise perturbation. Simulation results of the coefficients under randomly uncertain perturbations with various strengths are comparatively investigated with the traditional predictions under ideal conditions, from which the influences of random uncertain factors on dynamic coefficients are analyzed in terms of the rotor speed, pressure difference, and inlet whirl velocity. It is shown that the deviation levels of the dynamic coefficients are directly related to the random perturbations and routinely increase with such perturbation strengths, and the coefficients themselves may exhibit distinct variation patterns against the rotor speed, pressure difference, and inlet whirl velocity.


2022 ◽  
Vol 1211 (1) ◽  
pp. 012023
Author(s):  
A A Afanasev ◽  
V S Genin ◽  
L N Vasileva ◽  
V G Grigorev

Abstract A mathematical model of the magnetic field in the working gap of a brushless motor is considered in a case of rotor misalignment arising during manufacture, for example, due to defects in end shields, or in operation due to bearing wear. a gap in a uniform (circular ring). The stator gearing is taken into account on average using the Carter coefficient, the magnetic field in the inhomogeneous air gap, created by the rotor magnets and the stator winding current, is assumed to be plane-parallel, having a two-dimensional character. It was found that the rotor misalignment associated with the rotational movement of the eccentricity causes nonsinusoidality of the idle EMF and pulsation of the electromagnetic moment with a frequency 3p times higher than the rotor speed. When the eccentricity is stationary, a variable EMF is induced along the rotor shaft, causing an alternating current in the circuit: shaft-bearings-bearing shields-stator housing. To clarify the nature of the defect in order to identify the actual misalignment of the rotor, it is recommended to control currents and voltages using specialized software and hardware complexes for spectrum analysis.


Author(s):  
Behnam Nouri ◽  
ukasz Hubert Kocewiak ◽  
Torben Jersch ◽  
Gesa Quistorf ◽  
Christian Fenselau ◽  
...  

2021 ◽  
pp. 107-110
Author(s):  
Z.O. Znak

The process of plasmochemical decomposition H2S in a rotating reactor is studied. The generation of ultrahigh-frequency radiation in pulsed mode was synchronized with the rotation of the rotor. The influence of the rotor speed on the formation of the region of existence of a plasma discharge in the reactor and separation of H2S de-composition products are established. The content of hydrogen and hydrogen sulfide in the gas phase was analyzed at different points of the reactor along its radius. The concentration of H2 and H2S was determined by chromatog-raphy.


2021 ◽  
Author(s):  
Rajat Arora ◽  
Ramraj H. Sundararaj ◽  
T. Chandra Sekar ◽  
Abhijit Kushari

Abstract Turbines remain one of the most efficient devices for extracting energy from a flowing fluid. In a gas turbine engine, axial flow turbines are used to extract energy from the working fluid and drive the compressor, to which they are mechanically connected. To maximize the performance of the axial flow turbine, it is necessary to carry out a design optimization of the components while suitably accounting for losses generated by secondary flows. An axial flow turbine rig is designed, fabricated, and installed to better understand and improve upon secondary flow models used in design procedures. The rig is driven by a blower operating at a constant speed, capable of delivering a maximum airflow rate of 0.4 kg/s and a maximum pressure rise of 500 mbar across the device. The axial flow turbine is mechanically connected to a dynamometer capable of operating at a full load capacity of 5 kW and a maximum rotational speed of 10,000 RPM. The axial flow turbine, housed between the blower and dynamometer, consists of nozzle guide vanes followed by a rotor. The design pressure ratio is chosen as 1.04, based on the blower delivery conditions and dynamometer specifications. For an initial design, a low-pressure ratio low rotor speed design was selected, allowing for easy installation and testing of the rotating components. The design space for the axial flow turbine was generated by varying flow and geometrical parameters in suitable steps, using a program written in MATLAB 2020a. Using the input variables and applying free vortex theory for three-dimensional blade design, the aerodynamic design of the axial flow turbine was carried out. The axial flow turbine design is experimentally tested with suitable pressure measurements at every station. Experiments are conducted for four different air mass flow rates. At each air mass flow, the rotor speed is varied by increasing/decreasing the dynamometer load. The data is recorded and compared with the design point. The difference between the design and measured performance parameters is observed to be within acceptable limits.


Author(s):  
Dinh Chung Phan ◽  
Ngọc An Luu

This paper focused on evaluating the application of exponential moving average method into wind turbine to smooth its power output without an energy storage system or an anemometer. Wind turbine control modes including active power control mode and rotor speed control mode are considered. For each control mode, two positions of the Exponential Moving Average method in controller were compared to choose the best position. Additionally, the impact of smoothing factor on wind turbine performance was also considered to determine a reasonable value of the smoothing factor for each control mode. Simulation results in MATLAB/Simulink indicated that, for wind turbine using rotor speed control mode, the Exponential Moving Average method should be applied to reduce the variation of actual rotor speed signal while for wind turbine with the power control mode, it should be used to smooth reference power signal. From the performance of wind turbine with different smoothing factor values, we can suggest that the smoothing factor value should be set at 0.5 and 0.4 for the power control mode and the rotor speed control mode, respectively.


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