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The rotor–stator rubbing in rotating machinery generated as a consequence of rotor imbalance, shaft misalignment, and casing deformation is a potential threat to the machinery that seriously affects its performance. Timely prediction and correction of the rubbing are essential for the prolonged life of the machinery and its overall performance. A complete understanding of the system behavior during interaction is a great challenge for researchers working in the field of rotor dynamics. Rubbing phenomena involve complex contact nonlinearities and associated thermal effects, which makes the analysis very difficult. Research works in this field are started with the analysis of simple two degree-of-freedom models and now dealing with extensive three-dimensional finite element models. This paper provides a comprehensive review of different numerical models of rotor–stator rubbing with respect to their ability in simulating the actual response characteristics. A detailed description of contact modeling is also presented with the advantages and disadvantages of each model. Different methods for solving the numerical models are briefly explained. In addition, a commentary on different emerging techniques of rub identification is also reported. Finally, some informed recommendations on future directions are made by stating what lacks in the current research activities.

The variable stator vane system is a crucial component in preventing engine surge. In this study, a load is applied to the variable stator vanes to conduct a fatigue test, and relevant parameters are collected. The test results show that the force within this system is highly non-linear and complex. The amplitude of force is acceptable.

The advantage of amorphous alloy material is low loss, but its saturation magnetic flux density is low, only about 1.56 T, which is much lower than that of common silicon steel material, and it is difficult to meet the requirements of the new motor design. In this paper, we study the characteristics of the amorphous alloy under different external conditions, analyze the reasons affecting the iron loss from a microscopic point of view, and design a motor with a hybrid stator of amorphous alloy and silicon steel by refining the segmentation and optimizing and weakening the axial force, and further study the relationship between the amorphous ratio, the number of segments, the torque, and the efficiency.

Switched reluctance generator is widely used in the field of wind power generation. The efficiency of generators was usually related to the deviation angle. Compared with the single stator type switched reluctance motor, these dual-stator type switched reluctance motor models have the advantages of high accuracy, fast response and small size. An optimization method based on fuzzy algorithm and parameter scanning is proposed to improve the low speed performance of high efficiency generator. Taking the maximum output power, system efficiency and torque smoothing coefficient of DDSRG as the optimization goals, the effects of the turn-on angle, turn-off angle and reference current on the optimization goal are analyzed. The multi-objective optimization function is constructed, and the optimal combination value is obtained. The experiment proved that the parameter-controlled multi-objective optimization method could effectively improve the comprehensive performance of DDSRG in low-speed operation state.

This paper introduces a direct torque control technology based on NPC three-level SVPWM. It uses the Matlab platform to build a simulation model. It verifies the ideal waveform of the torque, magnetic chain, and current of the NPC-SVPWM direct torque control system under high speed and low speed with no load and load. This technique improves the waveform of the stator current and stator magnetic chain and solves the problem of the switching frequency not being fixed. Through this technique, it not only retains the robustness of the direct torque technique to the parameter change, but also effectively reduces the torque pulsation.

In the article, the design of a piezoelectric stick-slip rotary motor is proposed that can be used as the rotary drive part of a micro-nano operation. First, a force-coupled stator based on a flexible mechanism with a diameter of 23 mm was designed. Based on the designed stator, the structure of the rotary motor is constructed and its motion steps are analyzed. Then, finite element analysis is performed. Finally, the performance of the motor is tested and conclusions are drawn. The simulation and experimental results show that the developed motor performs well.

The performance of a stator current-based model reference adaptive systems (MRAS) speed estimator for sensorless induction motor drives is investigated in this study. The measured stator currents are used as a reference model for the MRAS observer to avoid the use of a pure integrator. A two-layer, online-trained neural network stator current observer is used as the adaptive model for the MRAS estimator which requires the rotor flux information. This can be obtained from the voltage or current models, but instability and dc drift can downgrade the overall observer performance. To overcome these problems of rotor flux estimation, an off-line trained multilayer feed-forward neural network is proposed here as a rotor flux observer. Hence, two networks are employed: the first is online trained for stator current estimation and the second is off-line trained for rotor flux estimation. Sensorless operation for the proposed MRAS scheme using current model and neural network rotor flux observers are investigated based on a set of experimental tests in the low-speed region. Using a neural network rotor flux observer to replace the current model is shown to solve the stability problem in the low-speed regenerating mode of operation.

This manuscript presents the application of a recently developed noise reduction technology, constituted by poro-serrated stator blades on a full-scale aircraft model, in order to reduce rotor-stator interaction noise in the fan stage. This study was carried out using the commercial lattice Boltzmann solver 3DS-SIMULIA PowerFLOW. The simulation combines the airframe of the NASA High-Lift Common Research Model with an upscaled fan stage of the source diagnostic test rig. The poro-serrations on the stator blades have been modeled based on a metal foam with two different porosity values. The results evidence that the poro-serrations induce flow separation on the stator blades, particularly near the fan-stage hub. Consequently, the thrust generated by the modified fan stage is lower and the broadband noise emission at low frequencies is enhanced. Nevertheless, the tonal noise components at the blade-passage frequency and its harmonics are mitigated by up to 9 dB. The poro-serrations with lower porosity achieve a better trade-off between noise emission and thrust penalty. An optimization attempt was carried out by limiting the application of porosity near the tip of the stator blades. The improved leading-edge treatment achieves a total of 1.5 dB in sound power level reduction while the thrust penalty is below 1.5%. This demonstrates that the aerodynamic effects of a leading-edge treatment should be taken into account during the design phase to fully benefit from its noise reduction capability.

In this paper, the pressure fluctuation under different working conditions of hydrofoil blade impeller (AF), offset blade impeller (SP) and offset winglet impeller (DAF) were measured and the influence of different structures on pressure fluctuation was analyzed. The results show that the discrete frequency caused by rotor-stator interaction (RSI) between impeller and tongue is the blade passing frequency ( f BPF ) and its harmonic frequency. Pressure fluctuation amplitude of blade passing frequency is obviously suppressed by offset blade. The value of pressure fluctuation of DAF is small near the tongue under small flow rate, and the energy suppression effect is obvious. With the increase of flow rate, the fluctuation energy of DAF increases gradually, and that of SP decreases gradually.

This article takes the active isolation platform voice coil motor actuator as the research object, designs a dual permanent magnet opposed excitation voice coil motor, designs the structural dimensions of the motor stator and mover, calculates the output thrust, simulates and optimizes the distribution of eddy currents generated during the motion of the voice coil motor mover, and finally compares the isolation performance of the isolation table before and after the mover optimization to determine the feasibility of the scheme.