International Journal of Rotating Machinery

Due to their limitations, conventional electric and water film dust removal methods struggle to handle fine dust. This study presented information on and examined the electrostatic water film cyclone dust collector (EWFCDC). By using the variable control approach, the impacts of inlet flow speed, water film flow rate, and corona pole form on dust removal performance were investigated. At EWFCDC, an orthogonal test was carried out to improve the test design and operating parameters based on the single-factor experiment. The pressure loss in the cyclone cylinder, when there is no water film and no corona pole, is a quadratic function of the inlet flow speed, and it is 2418.10 Pa at a 21.25 m/s inlet flow speed. The effectiveness of dust removal may be increased by increasing the water film flow rate. The effectiveness of dust removal is greatly influenced by the type of corona pole used, and cage needling thread is the optimal type. The electrostatic water film cyclone’s multimechanism coupling significantly increases the effectiveness of dust removal.

The rotary vector (RV) reducer is one of the widely used mechanical components in industrial systems, specifically in robots. The stability of the transmission performance of the RV reducer is crucial for the efficient operation of industrial equipment. The manufacturing and assembly errors of various components of the RV reducer during the production process are important factors that affect the transmission performance. However, in previous research work, the coupling effect of multiple errors on the transmission accuracy of RV reducer has not been fully considered. Furthermore, a vague relationship between system transmission errors and various errors also has not been thoroughly discussed, which presents a challenge to analyze and optimize the errors of components using the simulation technology of virtual prototype. Therefore, we propose a novel approach to use the response surface method (RSM) to investigate the transmission accuracy of RV reducer. Firstly, based on the constructed virtual prototype of RV reducer, the individual effects of different original errors on the overall transmission error are analyzed. Secondly, a response surface approximation model using RSM is constructed to analyze the effect of multiple error interactions on the transmission accuracy of the RV reducer, and the potential functional relationship between multiple error factors and the overall transmission error is also explored. Finally, the authenticity of the proposed approach is verified by setting up some comparative experiments. This study provides a reference for the efficient analysis and optimization of the transmission accuracy of RV reducers.

In order to study the elastic contact fatigue problems of composite cylindrical roller bearing, through the three stages of contact fatigue crack initiation, propagation, and ablating of cylindrical roller bearing theoretically analyzed, the subsurface stress is one of the factors of contact fatigue damage. By finite element method and theoretical analytic method with solid cylindrical roller bearing contact surface, the size and distribution of shear stress are analyzed, and comparing the calculation results of two methods, the comparison results show that the finite element method to calculate the bearing contact problem is scientific and reasonable. Through the finite element method of cylindrical roller bearing and elastic composite cylindrical roller bearing subsurface shear stress and equivalent stress on the surface of numerical analysis, the calculation results show that the subsurface stress value of elastic composite cylindrical roller bearings was 31.65% smaller than that of ordinary cylindrical roller bearings, and the distribution of the maximum subsurface stress value of elastic composite cylindrical roller bearings was shallower than that of cylindrical roller bearings. The elastic composite cylindrical roller bearings have significant advantages over cylindrical roller bearings in terms of subsurface stress and have stronger resistance to contact fatigue damage. The finite element method is used to analyze the subsurface stress of elastic composite cylindrical roller bearings with different filling degrees. The results show that the subsurface shear stress and equivalent stress values of elastic composite cylindrical roller bearings with filling degrees of 55% to 65% are maintained at a relatively low level, and the depth of the maximum stress is minimal, which is basically distributed on the surface of the rolling body. The magnitude and distribution of subsurface stresses in elastic composite cylindrical roller bearings provide a reference for more reasonable structural design.

The hydrodynamic thrust slider and journal bearings as well as hydrodynamic lubricated gears with the merit of energy conservation by the wall slippage are reviewed. The principle for designing these hydrodynamic contacts is to artificially set the wall slippage on the stationary surface in the hydrodynamic inlet zone. To design the wall slippage on the moving surface in the hydrodynamic outlet zone can also give additional benefits. The technical merits of these mechanical components are the improved load-carrying capacity and the lowed friction coefficient, i.e., the energy conservation due to the wall slippage. Owing to the designed wall slippage, the carried load of the hydrodynamic step bearing can be increased by 200%~400% while its friction coefficient can be reduced by 50%~85%, and the load-carrying capacity of the hydrodynamic journal bearing can be increased by nearly 100% while at the same time, its friction coefficient can be reduced by more than 60%. For hydrodynamic lubricated gear contacts, by covering ultrahydrophobic or oilphobic coatings on the slower moving surface, the friction coefficient can be approaching to vanishing and the contact load-carrying capacity can be increased very significantly for large slide-roll ratios under medium or heavy loads.

The purpose of this paper is to carry out an alternative to the present transient models for field wound synchronous machines, which is able to take into account the nonlinearity of the magnetic materials as well as the cross-magnetization. After presenting the principal model structures according to the state variables, a model based on two lookup tables for the magnetizing flux linkages is introduced and built step by step. The resulting signal flowchart shows an algebraic loop within the model, where the main flux linkage rapidly converges to its instantaneous value by simple iteration. The proof of this convergence is given for both saturated and unsaturated machine. Even though the proposed model uses the total linkage flux as state variable, as many alternative models do, it does not require the inversion of the current to flux linkage function (i.e., of lookup tables). This can spare a heavy computational task, especially with very large lookup tables. In the proposed model, the computational effort in the worst case scenario is reduced to few iterations (<10). Finally, the nonlinear behavior of the model is verified in four different transient scenarios by comparing its outcomes with those of a linear model for the same test machine.

The extensive use of the pump as a turbine (PAT) for micro-hydropower applications has a significant value from economic and technical viewpoints. However, the unavailability of the characteristics curve and relatively lower efficiency are the two basic limitations when considering pumps for power-generating applications. In this paper, the performance of the PAT is analyzed using the computational fluid dynamics (CFD) software called Ansys CFX in conjunction with standard -. Then, experiments were done to verify the results of the simulation. Measurement inaccuracy effects are also taken into account. The initial performance of the PAT is refined by controlling basic design parameters (i.e., increasing the number of impeller blades, decreasing blade thickness, blade tip rounding, and adjusting blade inlet angle). Additionally, a new modification method known as blade grooving is also introduced in this research. Finally, all listed modification techniques are applied simultaneously to achieve maximum performance. The output of the study confirms that the adopted modification techniques have a positive effect on performance improvement. When the number of impellers is increased, the power output is enhanced by 5.72%, and blade grooving provides the most efficiency improvement, i.e., 7.00%. But decreasing blade thickness has no remarkable impact on the performance; the power output and efficiency are improved by 1.24% and 2.60%, respectively. The maximum performance improvement was achieved when the modification techniques are applied simultaneously with 10.56 and 10.20 percent of power and efficiency increments, respectively. From the entire study, it can be concluded that the chosen design parameters have an important effect on stabilizing the internal flow, decreasing the required head, decreasing the hydraulic loss in the impeller, and increasing the overall performance. The study also helps to figure out which modification technique is the most practical.