Shaft Rotational Speed Research Articles

A Novel Diagnostic Feature for a Wind Turbine Imbalance Under Variable Speed Conditions.

Dependency between the conventional imbalance diagnostic feature and the shaft rotational speed makes imbalance diagnosis challenging for variable-speed machines. This paper focuses on an investigation of this dependency and on a proposal for a novel imbalance diagnostic feature and a novel simplified version for this feature, which are independent of shaft rotational speed. An equivalent mass-spring-damper system is investigated to find a closed-form expression describing this dependency. By normalizing the conventional imbalance diagnostic feature by the obtained dependency, a diagnostic feature is proposed. By conducting comprehensive experimental trials with a wind turbine with a permissible imbalance, it is justified that the proposed simplified version of imbalance diagnostic feature is speed-invariant.

Functionality of Bearings in the Shafts of a Vertical-Axis Wind Turbine

The article contains a description of the design solutions proposed by the authors for a hybrid wind turbine bearing, in which the sliding part takes over the load to the turbine shaft after reaching the shaft rotation speed, ensuring hydrodynamic lubrication of the plain bearing and relieving the rolling bearing. This allows for low starting resistance of the power plant and ensures quiet operation during use. Two conceptual solutions of a hybrid bearing were presented, differing in the shape of the plain bearing journal. A mechanism for automatic switching of the load between a rolling and a plain bearing was developed. A solid simulation model of this mechanism was built in the Autodesk Inventor—Dynamic Simulation software Inventor Professional 2023 environment, and its operation was simulated. The results confirmed the usefulness of using this design in shaft-bearing systems of wind turbines with a vertical axis of rotation. Based on the simulation, the speed at which the thrust roller bearing will be released was determined. Technical parameters of a plain bearing with a spherical journal shape were calculated. The height of the lubrication gap and the shaft rotational speed at which the bearing load capacity index reaches a critical value were determined.

Peanut Pickup Combine Harvester Seedling Vines Crushing Mechanism Performance Enhancement and Pilot Studies

Aiming at the current peanut pickup combine harvester seedling vines crushing mechanism operation qualified seedling length rate is low, the impurity rate is high, and the seedling vines crushing mechanism is optimized design. On the basis of the material characteristics of peanut seedling vines, taking the crushing mechanism as the research carrier, the interaction mechanism of the seedling vine mechanism was analyzed. Establish the mechanical model and motion trajectory model in the crushing process, simulate the peanut seedling vines crushing process based on the discrete element method, analyze the influence of the cutter shaft rotational speed, movement speed, and bending angle on the crushing of peanut seedling vines, and establish the regression model, and the results of the research show that the influence factors in the main order of priority are: knife shaft speed > movement speed > bending angle The optimal parameter combination is knife shaft speed 2171.94 r/min, movement speed 0.79 m/s, and bending angle 45°. According to the field test conditions, it is determined that the knife shaft rotational speed of 2170 r/min, movement speed of 0.8 m/s, and bending angle of 45° can make the peanut seedling vines crushing mechanism of the work performance to achieve a qualified seedling length rate of 97.292%, the rate of impurity content of 2.746%, and the error with the predicted value is less than 2%, which indicates that this study can provide a reference for the optimal design of the seedling vines crushing mechanism of the peanut pickup combine harvester.

Segmentalized amplitude normalization in feature extraction technique for diagnostics enhancement of bearing deterioration under varying speeds

This research investigated the feasibility of applying hardware order-tracking (HOT) and segmentalized amplitude normalization (SAN) to enhance the diagnosis of multiple bearing defects at different levels under varying rotation speeds. The vibration of operating bearings may present an energy variation phenomenon due to different levels of bearing defects, while the fluctuation of vibration amplitude may be attributable to changes in rotation speeds. These two factors inevitably interfere with each other when diagnosing bearing defects at multiple levels and classes under varying rotation speeds. In this paper, the research focuses on conducting an in-depth analysis of signal signatures, followed by providing a physical insight into feature extraction. Consequently, it enables the application of simple machine learning methods to accurately diagnose various bearing defects, even when dealing with significantly different patterns in training and testing data due to varying rotation speeds. To verify the effectiveness of the proposed SAN method for cases involving varying rotation speeds, the training and testing sets used datasets (vibration measurements) corresponding to different rotation speed profiles. The experimental and analytical results revealed that the proposed SAN method can normalize datasets with disparate vibration patterns, and alleviate the coupling of vibration energy variation and shaft rotation speed. This enhancement resulted in approximately 18.6% increase in the accuracy of bearing diagnosis for cases involving varying rotation speeds.

ЕКСПЕРИМЕНТАЛЬНІ ДОСЛІДЖЕННЯ БЕЗКОНТАКТНИХ МАГНІТОЕЛЕКТРИЧНИХ ТАХОГЕНЕРАТОРІВ

The paper is devoted to the study of the characteristics and operating modes of a brushless magneto-electric tachogenerator, which is implemented on the basis of a traditional radial electric machine with a slotless stator and permanent magnets on the rotor. Options for generating an DC output signal using diode and transistor rectifiers have been studied. The dependences of the average value of the output signal, the slope of the output signal, the coefficient of deviation of the characteristic from the specified value and the pulsation coefficient were obtained depending on the rotation speed of the rotor shaft. The influence of the capacitance of the filter capacitor on the magnitude of the output signal ripple amplitude has been studied. Ref. 13, fig. 9, table.

Regulating the surface area increase of zero-valent iron (ZVI) during ball milling: A study of the mechanical mechanism and low-carbon milling

This study investigates the effect of milling parameters on the specific surface area (SSA) increase of zero-valent iron (ZVI) powder, which is crucial for its environmental applications. Combining experimental and orthogonal design methodologies, the research explores how the parameters modulate the SSA. The operational factors are analyzed from the perspectives of bead momentum, kinetic energy, and energy efficiency. A regression model is proposed for the precise fabrication of ZVI with predetermined SSA. Furthermore, the study identifies optimized parameters that minimize energy consumption and carbon emissions. The results suggest that the optimal milling time is 10 min, with larger beads (2.0 mm), higher quality beads (0.75 kg), and higher shaft rotational speed (2000 rpm) significantly enhancing SSA. Discrete Element Method (DEM) simulations reveal micro-mechanical interactions, supporting the parameter selection scheme for maximizing SSA. The findings contribute to optimizing the milling process of the ductile ZVI powder for environmental clean-up.

Studies on Improving Seals for Enhancing the Vibration and Environmental Safety of Rotary Machines

There is a constant demand for higher equipment parameters, such as the pressure of a sealing medium and shaft rotation speed. However, as the parameters increase, it becomes more difficult to ensure hermetization efficiency. The rotor of a multi-stage machine rotates in non-contact seals. Seals’ parameters have a great influence on vibration characteristics. Non-contact seals are considered to be hydrostatodynamic supports that can effectively dampen rotor oscillations. The force coefficients of gap seals are determined by geometric and operational parameters. A purposeful choice of these parameters can influence the vibration state of the rotor. It is shown for the first time that the initially dynamically flexible rotor, in combination with properly designed seals, can become dynamically rigid. Analytical dependencies for the computation of the dynamic characteristics are obtained. The resulting equations make it possible to calculate the radial-angular vibrations of the rotor of a centrifugal machine in the seals and construct the amplitude–frequency characteristics. By purposefully changing the parameters of non-contact seals, an initially flexible rotor can be made rigid, and its vibration resistance increases. Due to this, the environmental safety of critical pumping equipment increases.

A π-Theorem-Based Advanced Scaling Methodology for Similarity Assessment of Marine Shafting Systems

This paper introduces a rigorous and comprehensive approach to the assessment of marine shafting systems through the utilization of an advanced π-Theorem-based scaling methodology. Integrating journal-bearing similarity assessment and shaft-line scaling methodology with advanced dimensional analysis, the study aims to provide a methodology foundation for systematic replication and analysis of marine shafting systems through scaled models. The proposed scaling methodology ensures geometric and mechanical similarity in terms of shaft-line deflection, considering key scaling parameters such as shaft length, diameter, weight, loads, rotational speed, material properties, bearing locations, and offsets. The advanced dimensional analysis computes specific non-dimensional ratios to guarantee a close resemblance between a real-size system and a scaled lab model. The methodology is analytically derived and validated with numerical simulations for a case study, conducting comparative analysis, evaluating discrepancies, and utilizing the integrated framework for experimentation.

Control program for the dosing system of dry bulk feed components

The development of intensive farming technologies is impossible without the introduction of modern technologies. The problem of compound feed production in the voiced aspect can be solved not only through the development of new machines and equipment, but also the introduction of modern control systems. The article presents an analysis of existing dispenser control systems. Based on the analysis of programs and control systems, it was revealed that almost all programs are designed to work in limited conditions, some of them do not take into account a number of factors affecting the accuracy of the material supply. Therefore, a control program for a twin-screw dispenser is proposed. When developing the management program, we started from the technological process of dosing. The possibility of controlling two augers was taken into account: first, a large auger (driven by an asynchronous electric motor) turns on and feeds the main part, then it turns off and the second small auger (driven by an asynchronous or stepper motor) turns on, which carries out the filling of the remaining part. In this case, signals about the amount of material supplied are transmitted from weighing sensors (strain gauges). The proposed control program for the twin-screw dispenser is developed for the TM241C24R PLC in the Structured Text (ST) programming language, one of the languages of the IEC61131-3 standard, in the EcoStruxure Machine Expert programming environment. The control is displayed on a liquid crystal display. The main screen displays basic information: the parameters of the electric motor, the recipe and the readings of the weighing sensors. The program allows you to control the operation of dispensers in several modes. In automatic mode, each dispenser supplies only one component. In manual control mode, the dispensers are started and stopped by the operator from the control panel. In this case, it is possible to set the rotation speed of the dispenser shaft. In the dosing mode with two augers, one component is dispensed with two augers. The proposed program will improve the accuracy of dosing in automatic mode.

Efficient boundary conditions identification in thermal simulation of the spindle system with reduced order model and differential evolution algorithm

The boundary conditions in thermal simulation of the spindle system are very complicated and the empirically calculated ones will usually result in a significant discrepancy between experiment and simulation. Thus, the optimal boundary conditions were identified by treating it as an inverse optimization problem in this paper. Moreover, to advance the optimization efficiency, a reduced order model is established to replace the time-consuming thermal simulation of the spindle system. By superposition of truncated eigenmodes and accurately predicted modal coefficients, the reduced order model can reconstruct the field very similar to thermal simulation. Experimental reconstruction of both the temperature field and thermal deformation field by the reduced order model demonstrated its at least 360 times speedup with 99.8 % accuracy compared to the actual thermal simulation. With the accurate reduced order model as a lightweight digital twin and using the differential evolution algorithm, three types of boundary conditions, i.e., the heat generation rates, the convective heat transfer coefficients and the thermal contact resistances, under the shaft rotation speed of 4,000r/min were identified within 11s. The maximum temperature simulation error was reduced from 85.6 % to 6.6 % and the thermal deformation simulation error was reduced from 60.9 % to 10.8 %.

Numerical simulation and experimental study on ultrafine powder spiral transportation degassing

Aiming at the problems of ultrafine powders of high air content and environmental pollution, low measurement accuracy and low efficiency in packaging and filling process, the research on degassing spiral powder transportation was carried out. Discrete element method and physical experiment method were used to simulate and test the mass flow rate, material density and dust concentration of packaging environment of equidistant spiral and degassing (variable pitch) spiral powder transportation, and the transportation effects of equidistant spiral and degassing spiral were analyzed.Simulation and test results show that the average mass flow rate of the degassing screw is 0.639 kg s−1 with the same screw outer diameter, inner shaft diameter, length and rotational speed, and the flow rate fluctuates with the percentage of fluctuation in the range of 7.19% − 10.02%. The degassing spiral increases the mass flow rate of the feeding device and reduces the flow fluctuation,and the maximum densification of the material was increased by about 7.25%. With the increase of rotational speed, the environmental dust lifting degree of both spiral filling processes increased, but under the same rotational speed, the dust lifting degree of the outlet of the degassing spiral was significantly reduced compared to the isometric spiral, and the rotational speed was increased from 80 to 120 r min−1, the maximum dust lifting degree of the isometric spiral was 37.88%, and the average dust lifting degree of the maximum was 25.59%, and the maximum dust lifting degree of the degassing spiral was 21.59%. The maximum dust lifting degree of the degassing spiral is 21.18%, and the maximum increase of the average dust lifting degree is 14.49%. Degassing spiral device effectively realises efficient and clean packaging of ultra-fine powder.

ТЕОРЕТИЧЕСКОЕ ОБОСНОВАНИЕ ЧАСТОТЫ ВРАЩЕНИЯ ЛОПАСТНОГО ПОГРУЗЧИКА В ЦИРКУЛЯЦИОННОМ СМЕСИТЕЛЕ

The purpose of the research is to substantiate the critical rotation speed of the working body based on force analysis and modeling of the movement of particles of a bulk product in a horizontal loader with radial blades located in a circulation mixer. The research methodology involved substantiating the maximum rotation speed of the loader working body based on an analysis of the forces acting on particles as they move by the loader blades and fall into the tray during flight. Based on the obtained expressions, the values of the indicators were modeled to analyze and substantiate rational values. The implementation of a numerical analysis of the obtained expressions based on force analysis and process modeling with the Mathcad mathematical package made it possible to identify the critical values of the rotation speed of the working body of a paddle loader based on the condition for the possibility of material coming off the blade and the condition for the possibility of particles flying from the blade into the receiving tray. Due to the need for material to flow off the blades and the rotation speed reduction factor of 0.9, the rotation speed of a blade loader with an outer diameter of blades of 0.24 m and an inner diameter of 0.17 m should not exceed 77 min-1 . The highest rotation speed of the working body shaft at which particles of material will enter the receiving tray area from the outer end of the blade is 43 min-1 , and from the inner end - 73 min-1 . In the process of manufacturing a circulating mixer with a radial blade loader for experimental studies, it should be possible to change the rotation speed up to 43 min-1 . To test theoretical principles in exploratory experiments, it is necessary to provide for the possibility of changing the rotation speed of the blade loader shaft to 70 min-1 .

Physics-based prognostics of rolling-element bearings: The equivalent damaged volume algorithm

This paper introduces a novel parameter related to bearing degradation, namely the Equivalent Damaged Volume (EDV). An algorithm capable of extracting EDV values from experimental data is detailed. To this end, the proposed technique relies on the comparison between experimental and numerical signals. The former are the result of an extensive campaign of run-to-failure tests performed on a dedicated test rig. On the other hand, the latter are obtained by means of a lumped parameter model that accounts for the angular extent and the depth of either localized or extended defects. The potential of this novel technique is demonstrated by exploiting the values obtained by the algorithm as inputs for a prognostic model. In particular, the developed model aims at predicting the time until a certain threshold on the equivalent damaged volume is crossed, regardless of the applied load and the shaft rotation speed. The advantages and downsides introduced by the proposed approach are thoroughly discussed by providing examples based on real degradation histories.

Optimization Design and Experiment of a Cotton Straw-Crushing Device Based on Computational Fluid Dynamics

In order to design the structure and optimize the working parameters of a straw-crushing device, and to improve the qualified rate of straw-crushing length and the rate of straw fluidity, the influence of the airflow characteristics and pressure distribution in the working state of the crushing chamber and the different structure and working parameters of the straw-crushing device on the airflow field were studied based on the computational fluid dynamics (CFD) software Fluent 19.2. The simulation results show that by changing the rotation speed of the cutter shaft, the negative pressure and mass flow rate of the inlet surface of the flow field reach the maximum values of 63.6 Pa and 1.64 kg/s, respectively, when the rotation speed of the cutter shaft is 2000 rpm, which proves that the rotation speed of the cutter shaft increases, and the feeding performance also increases. In the case of 0, 8 and 16 air knives, the peak flow velocity in the crushing chamber is 43.1 m/s, 50.1 m/s and 54.48 m/s, respectively, and the airflow in the crushing chamber is improved to a certain extent, which proves the feasibility of the air knives’ structure. In order to verify the simulation results, a field experiment was carried out. The results showed that the qualified rate of straw crushing was 94.13% and the drop rate was 4.26% under the conditions of a cutter shaft speed of 1800 rpm, a machine forward speed of 6 km/h and a height of 80 mm of the cutter off the ground. The field experiment and simulation show that the qualified rate of crushing increases with the increase in the rotation speed of the cutter shaft, but the increase rate slows down, and the random speed decreases. The drop rate decreases with the increase in tool height and tool speed. The air knife structure improves the crushing qualification rate and significantly reduces the drop rate, which verifies the simulation accuracy. This study provides a theoretical basis for the optimization of straw-crushing devices.

Optimizing high-speed rotating shaft vibration control: Experimental investigation of squeeze film dampers and a comparative analysis using Artificial Neural Networks (ANN) and Response Surface Methodology (RSM)

This research paper presents a comprehensive experimental and statistical approach for the analysis of vibration amplitudes in a high-speed rotating shaft employing a squeeze film damper (SFD). The research combines a comprehensive analysis that connects input parameters and response parameters, with a special emphasis on vibration amplitudes along the X and Z axes. This research utilizes the rigorous procedures of Response Surface Methodology (RSM) together with a Box-Behnken design and harnesses the capabilities of Artificial Neural Network (ANN) optimization techniques. The variables under scrutiny encompass critical factors such as shaft rotational speed, extending up to 8000 rpm, oil pressure, with a range extending up to 100 bar, and various oil mix ratios, spanning from 10 % to 50 %. Various statistical measures are computed to assess the errors and coefficients of determination of the projected models. The artificial neural network (ANN) model has shown somewhat reduced prediction errors and a greater coefficient of determination compared to the Response Surface Methodology (RSM) for both the x and z axes of vibration amplitude. The values of mean absolute error (MAE), root mean squared error (RMSE), and coefficient of determination (R-squared) are found for both x and z axes from RSM (3.50, 3.77), (4.50, 4.72), and (0.81, 0.79), (1.88, 1.70), (2.41, 2.12), and (0.94, 0.95), respectively, using the ANN model. The overall mean absolute percentage error (MAPE) from the ANN model of both the x and z axes (9.73 %, 9.38 %) is found to be lower compared to the RSM model (18.18 %–20.50 %). The conclusive research reveals that the artificial neural network (ANN) prediction model outperforms the regression model based on Response Surface Methodology (RSM), exhibiting superior accuracy in predicting vibration amplitudes. The ANN approach is an excellent option for calculating vibration amplitudes in high-speed rotating shafts. Additionally, it provides significant benefits in terms of effectiveness and time economy. This research provides valuable new insights into the most efficient modeling approaches for vibration management and highlights the benefits of using Artificial Neural Networks (ANN) for predictive assessments in this context. Particle Swarm Optimization is used to minimize the vibration amplitude of the shaft along the x and z axes using experimental data.

Enhancement of the lubrication system of an internal combustion engine

BACKGROUND: The modernized design of the lubrication system with an individual electric-driven oil pump ensures the oil supply to remote and loaded parts, regardless of the crankshaft speed, starting mode and engine warm-up. AIM: Study of the main directions for enhancement of the lubrication systems of piston engines in order to assess the option of using an autonomous electric drive. METHODS: The design of an adjustable inductor electric drive with microprocessor control is proposed as a drive. The ability to keep rotation speed of the pump gears accurately is ensured using a controlled inductor electric motor, depending on the pressure in the lubrication system. RESULTS: The design and technological implementation of the proposed method of driving an oil pump does not require major changes to the engine design. The layout of the oil pump at the engine is simplified. CONCLUSIONS: The proposed design of the lubrication system of an internal combustion engine ensures optimal rotation speed of the pump shaft regardless of the operating modes of the piston engine, resulting in an increase in engine operating life.

Analysis of Water-Lubricated Journal Bearings Assisted by a Small Quantity of Secondary Lubricating Medium with Navier–Stokes Equation and VOF Model

Due to the low viscosity of water, water-lubricated bearings are susceptible to significant wear and noise in demanding operating conditions. It has been demonstrated that a small quantity of secondary lubricating medium can improve the lubrication performance of water-lubricated contact surfaces and achieve the purpose of temporary risk aversion. As a further step, the feasibility of the proposed idea is experimentally validated on a water-lubricated bearing test bench. A numerical model that couples the N–S equation and the VOF model is then developed to investigate the behavior of the flow field lubricated by pure water and water with a small quantity of the secondary lubricating medium. This model provides the predictions of important quantities such as the load-carrying capacity, the secondary lubricating medium volume fraction and the contact pressure under different lubricated conditions. The results show that the secondary lubricating medium can enter into the contact region and improve the lubrication performance of water-lubricated bearings, especially at lower shaft rotational speeds. Therefore, the feasibility of our proposed idea is verified, which provides a promising approach to reduce the wear and friction of water-lubricated bearings when they encounter short-time severe working conditions.

Results of the study of rotary feed pump with separator and screw feeder

The article presents the results of an analysis of experimental studies of a rotary lobe pump with a separator and a screw feeder. The pressure loss in the feed line, the influence of the shape of the separator and the angle between its working edges on the performance characteristics of the pump, the influence of the performance of the screw feeder on the characteristics of the pump and the influence of the rotation speed of the pump shaft on its characteristics are studied. characteristics. As a result of experimental studies, it was established that a rotary pump with a screw feeder reliably transports feed mixtures with grass paste with a moisture content of 74% or more and feed mixtures without grass with a moisture content of 68% or more at a pressure in the discharge line of 0.4 MPa. In this case, the speed of the feed mixture in the suction cavity of the pump must be at least 0.42 m/s, which is ensured by a screw feeder.

Hydrodynamic lubrication behavior under miscellaneous operational conditions via CGB numerical model

The current study is basically focused on investigating the possible ways to enhance the lubricating oil film performance and hence ship energy efficiency of marine journal bearings in general terms. For the intended purpose, a novel numerical Circumferential Grooved Bearing (CGB) model was developed to assess journal bearing operating conditions based on versatile simulation analyses. Prior to all conducted test trials, the model validation has been confirmed based on the conformity between numerical outcomes and those derived from experimental procedures depending on Universal Journal Bearing Test Rig. CGB performance was evaluated at slow speed variations from 25 rpm up to 125 rpm and different applied loads utilizing the two lubricant oil grades of 5W40 and 0W30. Reducing shaft rotational speed by 80% was found to incur a reduction in the maximum oil film pressure value by 1.17 bar and 0.97 bar for the two aforementioned lubricants respectively. Further, the increase of applied loads from 1079 N up to 1471 N at a constant speed of 75 rpm reduces the maximum oil film pressure ratio by 0.14 and 0.18 for the two oil grades subsequently.

ПРОГРАММНЫЙ КОМПЛЕКС ДЛЯ РЕАЛИЗАЦИИ АСИНХРОННОГО ЧАСТОТНОГО ПУСКА ВЫСОКОВОЛЬТНЫХ ДВИГАТЕЛЕЙ И СНИЖЕНИЯ ВРЕМЕНИ ПЕРЕРЫВА В РАБОТЕ ДВИГАТЕЛЯ ПРИ КРАТКОВРЕМЕННОЙ ПОТЕРЕ ПИТАНИЯ

Relevance Most of the electricity consumed comes from electric drives (ED) of various technological processes. The most common way to increase the efficiency of an electric drive is the use of a variable frequency drive (VFD). However, the use of VFDs in some cases causes a decrease in the operating efficiency of the electric drive, this is due to the high sensitivity of the frequency converter to network voltage dips, leading to the failure of the inverter and to the stop of the technological process. A current direction is the development of algorithmic methods for increasing the stability of electric drives. Aim of research Increasing the stability of a frequency-controlled motor during emergency conditions in the power supply system. Development of a power supply circuit for an electric drive, and research into the algorithm for operating the inverter in emergency modes. Methods The study of the developed method was carried out in the Matlab Simulink software package. Results A power supply circuit for an electric drive with a synchronized bypass line and a main line with a frequency converter operating according to the developed algorithm is proposed. A study of the influence of the error in measuring the shaft rotation speed on the accuracy of maintaining the recuperation of the DC transformer, as one of the ways to increase the resistance of the VFD to short-term voltage dips in the network was carried out.