Subjects -> MANUFACTURING AND TECHNOLOGY (Total: 363 journals)
    - CERAMICS, GLASS AND POTTERY (31 journals)
    - MACHINERY (34 journals)
    - MANUFACTURING AND TECHNOLOGY (223 journals)
    - METROLOGY AND STANDARDIZATION (6 journals)
    - PACKAGING (19 journals)
    - PAINTS AND PROTECTIVE COATINGS (4 journals)
    - PLASTICS (42 journals)
    - RUBBER (4 journals)

MACHINERY (34 journals)

Showing 1 - 27 of 27 Journals sorted alphabetically
Acta Mechanica Solida Sinica     Hybrid Journal   (Followers: 8)
Advanced Energy Materials     Hybrid Journal   (Followers: 31)
Applied Mechanics Reviews     Full-text available via subscription   (Followers: 27)
CORROSION     Full-text available via subscription   (Followers: 20)
Electric Power Components and Systems     Hybrid Journal   (Followers: 7)
Foundations and TrendsĀ® in Electronic Design Automation     Full-text available via subscription   (Followers: 1)
International Journal of Machine Tools and Manufacture     Hybrid Journal   (Followers: 8)
International Journal of Machining and Machinability of Materials     Hybrid Journal   (Followers: 4)
International Journal of Manufacturing Technology and Management     Hybrid Journal   (Followers: 8)
International Journal of Precision Technology     Hybrid Journal   (Followers: 1)
International Journal of Rapid Manufacturing     Hybrid Journal   (Followers: 3)
International Journal of Rotating Machinery     Open Access   (Followers: 2)
Journal of Machinery Manufacture and Reliability     Hybrid Journal   (Followers: 2)
Journal of Manufacturing and Materials Processing     Open Access  
Journal of Mechanics     Hybrid Journal   (Followers: 9)
Journal of Strain Analysis for Engineering Design     Hybrid Journal   (Followers: 5)
Journal of Terramechanics     Hybrid Journal   (Followers: 4)
Machine Design     Partially Free   (Followers: 184)
Machine Learning and Knowledge Extraction     Open Access   (Followers: 12)
Machines     Open Access   (Followers: 4)
Materials     Open Access   (Followers: 4)
Mechanics Based Design of Structures and Machines: An International Journal     Hybrid Journal   (Followers: 8)
Micromachines     Open Access   (Followers: 2)
Pump Industry Analyst     Full-text available via subscription   (Followers: 1)
Russian Engineering Research     Hybrid Journal  
Sensor Review     Hybrid Journal   (Followers: 2)
Surface Engineering and Applied Electrochemistry     Hybrid Journal   (Followers: 6)
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International Journal of Rotating Machinery
Journal Prestige (SJR): 0.193
Citation Impact (citeScore): 1
Number of Followers: 2  

  This is an Open Access Journal Open Access journal
ISSN (Print) 1023-621X - ISSN (Online) 1542-3034
Published by Hindawi Homepage  [339 journals]
  • Experimental and Numerical Studies of the Film Cooling Effectiveness
           Downstream of a Curved Diffusion Film Cooling Hole

    • Abstract: Film cooling technology is a commonly used method for thermal protection of gas turbines’ hot sections. A new, shaped, film cooling hole is proposed in this study. The geometry is made of a straight-through cylindrical feed hole at an inclination angle of 30° followed by an expansion section. The expansion section is created by the rotation of the same circular hole on the inclination plane about an axis normal to that plane which passes through the center of the feed hole exit area. This shape was designed to decrease the deteriorating effects of kidney vortices by proper distribution of the coolant flow emerging from the hole exit area. Cases with four rotation angles (7°, 14°, 17.5°, and 21°) were studied both experimentally and numerically and for the blowing ratios of 0.5, 1, and 2.0. For comparisons, the commonly used 7°-7°-7° diffusion hole geometry was also tested under otherwise identical conditions. For data collection, the pressure-sensitive paint (PSP) technique was used to measure the film cooling effectiveness. Streamwise- and spanwise-averaged film effectiveness results were obtained to compare the performance of different geometries. The main conclusions were that the case of 21° rotation angle produced the highest film effectiveness and outperformed the 7°-7°-7° diffusion hole geometry.
      PubDate: Mon, 09 May 2022 09:20:02 +000
       
  • Type Synthesis Based on Modular Combination with Virtual Rotation Center
           and Application

    • Abstract: Type synthesis of mechanical structure is of great significance to the realization of mechanism target function, systematization, and stability of mechanical device. The type synthesis method of multilinkage robot has been given high demands with increasing number of degrees of freedom and high flexibility in special occasions. In order to improve the workspace and flexibility of mechanism, this paper studies the existing type synthesis theory and proposes a type synthesis method of modular combination with virtual rotation centers. Firstly, modular units are built. Secondly, modular units are expanded according to the needed paths. In the end, the expanded modular units are combined to form the kinematic linkages. Based on the proposed method, the configuration design of the aerial working platform and the self-adaptive levelling platform is completed. The stabilities of two platforms are checked by modal analysis. The prototype products are manufactured, respectively, for further verifying validity of the method. The designed aerial working platform with virtual rotation centers can achieve 360° rotating large workspace, more compact mechanical structure, and short arrival time at the same height than the common scissor-type and mast-type aerial working platforms. The designed adaptive levelling platform is tested that ensures the levelling of the upper surface at different inclinations. The method can provide new idea for the mechanism configuration and expand the application scope of new mechanisms.
      PubDate: Thu, 03 Mar 2022 09:05:01 +000
       
  • Effect of Pole Number on Generator End Winding Electromagnetic Force and
           Mechanical Response before and after RISC

    • Abstract: This paper comparatively studies on the end winding electromagnetic force and mechanical response for generators with different numbers of poles. The analytical expression of the end winding electromagnetic force is derived under the rotor winding interturn short circuit (RISC) considering the pole number. Meanwhile, the three-dimensional transient finite element simulation is carried on two generators with one-pair poles and three-pair poles. Then, the frequency composition and amplitude variation characteristics of the radial, axial, and tangential electromagnetic forces are analyzed. Further, the maximum stress and deformation on the end winding are calculated and the similarity and difference of the coil failure law are obtained for two kinds of generators. It is found that RISC will bring odd harmonics to electromagnetic force for one-pair pole generators but it will bring odd and fraction harmonics for multipair pole generators. Moreover, the max mechanical response under RISC will decrease for one-pair pole generators but it will increase for multipair pole generators.
      PubDate: Thu, 23 Dec 2021 09:20:01 +000
       
  • Experimental Research on the Similarity of Rime Icing on a Cylinder
           Rotating around Its Horizontal Axis

    • Abstract: Ice accumulation on the blade of a wind turbine surface seriously threatens the operational safety of the turbine; therefore, the research on this problem is very important. In this paper, a new similarity criterion of icing shape for a rotational model was proposed based on the similarity criterion for translational motion models in the aviation field, and experimental studies on the similarity of the rotational model icing were carried out. To validate the similarity criterion, icing wind tunnel tests were carried out with aluminum cylinders with diameters of 40 mm and 20 mm. Key parameters for the experiment, such as wind speed, temperature, liquid water content, medium volume diameter, and test time, were selected based on the criterion. All the icing tests were carried out in a new self-designed icing wind tunnel test system based on natural low-temperature conditions. The icing shapes observed in the tests were confirmed after many repetitions. To quantitatively analyze the similarity between different sizes of ice shapes, a dimensionless method for evaluating the similarity of ice shapes of different sizes was defined based on the typical characteristics of ice shapes. The research results show that the similarity score between two sizes of ice shapes under different test conditions is 81%~90%. The accuracy and applicability of the icing shape similarity criterion were thus validated. The research results in this paper lay a theoretical and experimental foundation for exploring the icing shape similarity of a rotating model.
      PubDate: Mon, 08 Nov 2021 13:05:01 +000
       
  • Analysis of the Rotor Magnetomotive Force of Built-In Radial Permanent
           Magnet Generator for Vehicle

    • Abstract: Permanent magnet generator (PMG) for vehicles has attracted more and more attention because of its high efficiency, high power density, and high reliability. However, the weak main air-gap magnetic field can affect the output performance and the normal use of electrical equipment. Aiming at the problem, this paper took the rotor magnetomotive force (MMF), the direct influencing parameter of the main air-gap magnetic field, as the research object, deduced the analytical expression of rotor MMF of the built-in radial PMG in detail, and analyzed its main influencing factors in analytical expression, including the permanent magnet steel (PMS) material, the thickness of PMS in magnetizing direction, the vertical length of the inner side of PMS, and the effective calculation length of PMS. Based on this, the rotor parameters were optimized to obtain the best values. After that, the finite element simulation and prototype test of the optimized generator were carried out. The comparative analysis results showed that the optimized rotor parameters could effectively improve the rotor MMF and optimize the output performance of the generator.
      PubDate: Mon, 08 Nov 2021 09:05:01 +000
       
  • Structures Dynamic Property Analysis of Elastic Composite Cylindrical
           Rolling Element

    • Abstract: Elastic composite cylindrical roller bearing is a novel type of roller bearing whose rolling element is designed by innovating the rolling element structure of cylindrical roller bearings. For the purpose of investigating the dynamic properties of the rolling elements with different structural parameters and solving the modes of elastic composite cylindrical rolling element with different filling degrees, first, this study compares elastic composite cylindrical rolling element to solid cylindrical rolling element, in terms of natural frequency and vibration mode. Next, the integration time step is determined, based on the natural frequency of the vibration in the Y direction, the response of various rolling element, under impact loads, is solved. Furthermore, the laws of the energy changes and nodal displacement variations of rolling element are explored, at different filling degrees. Finally, adopting the decay method, the damping ratio of elastic composite cylindrical rolling element, under different structural parameters and external loads, is calculated. According to the results, with the increase of filling degree, the natural frequencies of various orders of elastic composite cylindrical rolling element gradually declined. The damping ratio of rolling elements decreased, as the filling degree increased, while it could be changed by adjusting the structural dimensions of rolling elements. The analysis results of this study provide some theoretical reference for studies on the parameter optimization of rolling element structures, the vibration and noise reduction of elastic composite cylindrical roller bearings.
      PubDate: Mon, 18 Oct 2021 11:50:01 +000
       
  • Experimental Film Cooling Effectiveness of Three-Hole-Branch Circular
           Holes

    • Abstract: A three-hole-branch geometry for film cooling is proposed. Each branch is made up of a streamwise 30°-angled circular hole with a circular hole of the same diameter on each side of it. These three holes share the same inlet area on the coolant supply side. Three side hole inclination angles of 30°, 37.5°, and 45° and three branch angles (the angle between the main and side holes) generated nine configurations that were tested for four blowing ratios of 0.5, 1, 1.5, and 2. To their benefits, these straight-through circular holes could easily be laser drilled on the airfoils or other gas turbine hot section surfaces. For comparative evaluation of these film hole geometries, the commonly used 7°-7°-7° diffusion hole geometry with the same inlet hole diameter was tested as a baseline under otherwise identical conditions. The pressure-sensitive paint (PSP) technique was utilized to test these geometries for their film cooling effectiveness. Depending on the branch geometry, for the same amount of coolant, some configurations were found to be superior to the baseline case for stream- or spanwise film cooling distributions while for the steeper side hole angles, these branched holes did not perform as well as the baseline case. The main conclusion is that the three holes with the same inclination angle of 30° exhibited the best film cooling effectiveness performance including the baseline geometry.
      PubDate: Mon, 11 Oct 2021 10:20:02 +000
       
  • Tailored Centrifugal Turbomachinery for Electric Fuel Cell Turbocharger

    • Abstract: Hydrogen fuel cell technology is identified as one option for allowing efficient vehicular propulsion with the least environmental impact on the path to a carbon-free society. Since more than 20 years, IHI is providing charging systems for stationary fuel cell applications and since 2004 for mobile fuel cell applications. The power density of fuel cells substantially increases if the system is pressurized. However, contaminants from fuel cell system components like structural materials, lubricants, adhesives, sealants, and hoses have been shown to affect the performance and durability of fuel cells. Therefore, the charging system that increases the pressure and the power density of the stacks inevitably needs to be oil-free. For this reason, gas bearings are applied to support the rotor of a fuel cell turbocharger. It furthermore comprises a turbine, a compressor, and, on the same shaft, an electric motor. The turbine utilizes the exhaust energy of the stack to support the compressor and hence lower the required electric power of the air supply system. The presented paper provides an overview of the fuel cell turbocharger technology. Detailed performance investigations show that a single-stage compressor with turbine is more efficient compared to a two-stage compressor system with intercooler. The turbine can provide more than 30% of the required compressor power. Hence, it substantially increases the system efficiency. It is also shown that a fixed geometry turbine design is appropriate for most applications. The compressor is of a low specific speed type with a vaneless diffuser. It is optimized for operating conditions of fuel cell systems, which typically require pressure ratios in the range of 3.0.
      PubDate: Mon, 27 Sep 2021 10:35:01 +000
       
  • Experimental Investigations on Leakages in Positive Displacement Machines

    • Abstract: The clearance gaps in positive displacement machines such as compressors, pumps, expanders, and turbines are critical for their performance and reliability. The leakage flow through these clearances influences the volumetric and adiabatic efficiencies of the machines. The extent of the leakage flow depends on the size and shape of clearance paths and pressure differences across these paths. Usually, the mass flow through the gaps is estimated using the isentropic nozzle equation with the flow coefficients applied to correct for the real flow conditions. However, the flow coefficients applied generally do not take into account the shape and size of these leakage paths. For that reason, a proper understanding of the relationship between flow coefficients and shape parameters is crucial for an accurate prediction of leakage flows. The present study investigates the influence of the various dimensionless parameters such as Reynolds number, Mach number, and pressure ratio on the flow coefficients for circular and rectangular clearance shapes. The flow coefficients are determined by comparing the experimental values obtained in an experimental test rig and the flow rates obtained from the isentropic nozzle equation. It is observed that in the case of circular clearances, the mean deviation of the experimental leakage results (in comparison to the analytical results using isotropic nozzle equations) is +9.1%, which is significantly lower than the mean deviation (+20.5%) in the case of rectangular clearance leakages. The study indicates that the isentropic nozzle equation method is more suitable for predicting the leakages through the circular clearances and needs modifications for consideration of the rectangular clearances. Using regression analysis, empirical correlations are developed to predict the flow coefficient in terms of Reynolds number, Mach number, pressure ratio, aspect ratio, and β ratio, which are found to match within ±6.4 percent of the numerical results for the rectangular clearance and within the range of -3.6 percent to +5.1 percent of the numerical result for the circular clearance. The empirical relationships presented in this study can be extended to evaluate the flow coefficients in a positive displacement machine.
      PubDate: Sat, 21 Aug 2021 07:35:02 +000
       
  • Critical Hydraulic Eccentricity Estimation in Vertical Turbine Pump
           Impeller to Control Vibration

    • Abstract: In many applications, pumps are tested against standard specifications to define the maximum allowable vibration amplitude limits of a pump. It is essential to identify the causes of vibration and methods to attenuate the same to ensure the safe and satisfactory operation of a pump. Causes of vibration can be classified mainly into mechanical and hydraulic nature. Respective unbalance masses are the two major factors which cause dynamic effects and excitation forces leading to undesirable vibrations. In this paper, the procedure of vibration magnitude measurement of a vertical turbine pump at site and the process of dynamic balancing to measure mechanical unbalance of an impeller are explained. After that, the impact of hydraulic eccentricity on the vibration displacement of a vertical turbine pump has been explained using numerical simulation procedure based on “One-way Fluid Structure Interaction (FSI).” The experimental results from a pump at site are used to compare the numerical results. After the solver validation, the one-way FSI approach is used to find the critical hydraulic eccentricity magnitude of a vertical turbine pump impeller to limit the vibration magnitudes on motor component to less than 100 μm. From the numerical simulations, it is deduced that the critical hydraulic eccentricity should be limited to 400 μm in and direction. The process can be used as a guideline procedure for limiting the hydraulic unbalance in vertical turbine pumps by limiting the hydraulic eccentricity.
      PubDate: Sat, 31 Jul 2021 06:35:02 +000
       
  • Effects of Side Load Chains of a Combine Harvester on Unbalanced Dynamic
           Vibrations of Its Threshing Drum

    • Abstract: In order to study the influence of the side drive on the balance state of the threshing drum, this paper used the side eccentric load chain drive as the power on the threshing drum dynamic balance test bench. By analyzing the influence of different radial phases, different axial distances, and spiral combinations of the threshing drum on the counterweight, this paper studies the law of the effect of side partial load chain drive on the dynamic balance of the threshing drum and finds that the side chain drive has obvious influence on the unbalance phase of the threshing drum and the change of the axial distance of unbalance has little effect on the equilibrium state of the threshing drum. And from this, a vibration balance method based on the equivalent unbalance of the chain drive is proposed, which can predict and calculate the unbalance of the threshing drum. The unbalance of the threshing drum predicted by this method is smaller than the actual measured unbalance. The maximum error is 32.64% and the minimum error is 4.6%. In the two tests, the predicted unbalance is 1.24 mm/s in amplitude and 270 degrees in phase and amplitude 1.4 mm/s and phase 120 degrees, respectively. The measured unbalance is amplitude 1.587 mm/s and phases 286 degrees. The error between prediction and actual measurement is less than 32.64%, and the unbalance amplitudes that can be reduced by one-time dynamic balance are 0.856 mm/s and 0.674 mm/s, respectively. The research results in this paper provide an effective method for the balance state of the multidrum side chain transmission.
      PubDate: Wed, 30 Jun 2021 06:20:02 +000
       
  • Multisource Fault Signal Separation of Rotating Machinery Based on Wavelet
           Packet and Fast Independent Component Analysis

    • Abstract: The vibration signal of rotating machinery compound faults acquired in actual fields has the characteristics of complex noise sources, the strong background noise, and the nonlinearity, causing the traditional blind source separation algorithm not be suitable for the blind separation of rotating machinery coupling fault. According to these problems, an extraction method of multisource fault signals based on wavelet packet analysis (WPA) and fast independent component analysis (FastICA) was proposed. Firstly, according to the characteristic of the vibration signal of rotating machinery, an effective denoising method of wavelet packet based on average threshold is presented and described to reduce the vibration signal noise. In the method, the thresholds of every node of the best wavelet packet basis are acquired and averaged, and then the average value is used as a global threshold to quantize the decomposition coefficient of every node. Secondly, the mixed signals were separated by using the improved FastICA algorithm. Finally, the results of simulations and real rotating machinery vibration signals analysis show that the method can extract the rotating machinery fault characteristics, verifying the effectiveness of the proposed algorithm.
      PubDate: Mon, 31 May 2021 12:05:01 +000
       
  • Research and Development of a Small-Scale Icing Wind Tunnel Test System
           for Blade Airfoil Icing Characteristics

    • Abstract: In order to study the icing mechanism and anti-icing technology, a small low-speed reflux icing wind tunnel test system was designed and constructed. The refrigeration system and spray system were added to the small reflux low-speed wind tunnel to achieve icing meteorological conditions. In order to verify the feasibility of the test system, the flow field uniformity, temperature stability, and liquid water content distribution of the test section were tested and calibrated. On this basis, the icing tests of an aluminium cylinder, an NACA0018 airfoil, and an S809 airfoil were carried out, and the two-dimensional ice shape obtained by the test was compared with the two-dimensional ice shape obtained by the numerical simulation software. The results show that in the icing conditions and icing time studied, the parameters of the test system are stable, and the experimental ice shape is consistent with the simulated ice shape, which can meet the needs of icing research.
      PubDate: Sat, 15 May 2021 07:05:01 +000
       
  • Optimization Analysis of Automotive Asymmetric Magnetic Pole Permanent
           Magnet Motor by Taguchi Method

    • Abstract: In order to improve the air-gap flux density of the permanent magnet synchronous motor and reduce the cogging torque, a novel structure with asymmetric magnetic poles for automobile was proposed. Based on the characteristics of the parallel magnetic circuit, the magnetic flux path diagram is established. And the equivalent magnetic circuit model is established by the equivalent magnetic circuit method. The Taguchi method is used to be a multiobjective optimization algorithm. The total harmonic distortion of the air-gap flux density is the first optimization goal. The second and third optimization goals are the cogging torque and the average of output torque, respectively. And the torque ripple is a constraint condition. The optimized parameter combination is obtained by the Taguchi method. Finite element simulation analysis and prototype test are carried out for the optimized motor structure. The results show that the total harmonic distortion of air-gap flux density is reduced by 36.7% comparing with the initial structure. The cogging torque is reduced by 26.0%. And the average output torque is increased by 4.8%.
      PubDate: Sat, 17 Apr 2021 07:35:02 +000
       
  • Study of Groove Parameters on the Hydrodynamic Behavior of Spiral-Grooved
           Thrust Bearing with Gas Lubricant

    • Abstract: The gas-lubricated thrust bearing is widely used in agriculture mechanical systems, and the groove shape plays an important role on the hydrodynamic behavior of spiral-grooved thrust bearing (SGTB). Although the groove shape may change smaller, it is clear that the hydrodynamic response is very sensitive to the groove parameters. This paper proposes a computational method for the analysis of SGTB with gas lubricant, considering the effects of groove parameters. With the compressibility taken into account, the evaluation of lubrication performance for SGTB is obtained by the CFD technology. Also, the simulation results are compared with the published data, which indicates that the presented model of SGTB is able to obtain more realistic results of hydrodynamic characteristics of SGTB. Moreover, the mapping relationship between groove parameter and hydrodynamic behavior of SGTB is represented.
      PubDate: Wed, 07 Apr 2021 09:20:01 +000
       
  • Effect of Static Rotor Eccentricity on End Winding Forces and Vibration
           Wearing

    • Abstract: In order to study the vibration wearing regularity and the strength failure point of stator end windings before and after static rotor eccentricity, the three-dimensional electromagnetic forces and the subsequent mechanical responses are studied in this paper. The electromagnetic force, stress, and deformation on the end winding of the QFSN-600-2YHG turbo-generator are calculated by the finite element method (FEM) through an electromagnetic-structure coupling. The radial vibration characteristics of the winding are verified by experiments. It shows that the vibration wearing in the same layer is more serious than that between two neighboring layers. For different layers, the interphase coils endure a larger wearing risk than the innerphase coils. Inside the same phase, the last coil along the rotating direction has the highest risk of insulation wearing. The occurrence of static rotor eccentricity will significantly increase the electromagnetic forces and the vibration amplitudes on some coils. The end-phase coil which is close to the minimum air-gap point is the most dangerous one due to the lasting overstresses and the intensified deformations.
      PubDate: Tue, 30 Mar 2021 06:05:01 +000
       
  • Assessment of Equipment Operation State with Improved Random Forest

    • Abstract: To accurately assess the state of a generator in wind turbines and find abnormalities in time, the method based on improved random forest (IRF) is proposed. The balancing strategy that is a combination of oversampling technique (SMOTE) and undersampling is applied for imbalanced data. Bootstrap is applied to resample original data sets of generator side from the supervisory control and data acquisition (SCADA) system, and decision trees are generated. After the decision trees with different classification capabilities are weighted, an IRF model is established. The accuracy and performance of the model are based on 10-fold cross-validation and confusion matrix. The 60 testing sets are assessed, and the accuracy is 95.67%. It is more than 1.67% higher than traditional classifiers. The probabilities of 60 data sets at each class are calculated, and the corresponding state class is determined. The results show that the proposed IRF has higher accuracy, and the state can be assessed effectively. The method has a good application prospect in the state assessment of wind power equipment.
      PubDate: Tue, 09 Mar 2021 11:05:01 +000
       
  • The Air Lubrication Behavior of a Kingsbury Thrust Bearing Demonstration

    • Abstract: In order to understand the air lubrication behavior of Kingsbury thrust bearing demonstration, an experimental and theoretical investigation on a simulated Kingsbury thrust bearing was presented. The motions of the thrust disk and tilting pads were measured by eddy current sensors for three mass load cases. A simplified theoretical model governing the motion of the thrust disk was established. The bearing successfully passed the examination of lamp extinction and maintained the maximum rotation time of 16 s. The effective hydrodynamic film with a thickness of about 5 μm was concentrated on the middle region of the working surface under a flatness of 0.010 mm. The adverse effect of the three surface bumps was minimized by the swing motion of tilting pads. Moreover, about 1/3 air film thickness was shown to be wasted due to the surface irregularity. However, the requirements of surface quality and misalignment were appropriately relaxed through the design of the centrally pivoted tilting pads. This design is conducive to thin-film lubrication and is a potential application for microturbines.
      PubDate: Sat, 27 Feb 2021 13:50:01 +000
       
  • Validation of the Axial Thrust Estimation Method for Radial Turbomachines

    • Abstract: The fast preliminary design and safe operation of turbomachines require a simple and accurate prediction of axial thrust. An underestimation of these forces may result in undersized bearings that can easily overload and suffer damage. While large safety margins are used in bearing design to avoid overloading, this leads to costly oversizing. In this study, the accuracy of currently available axial thrust estimation methods is analyzed by comparing them to each other and to theoretical pressure distribution, numerical simulations, and new experimental data. Available methods tend to underestimate the maximum axial thrust and require data that are unavailable during the preliminary design of turbomachines. This paper presents a new, simple axial thrust estimation method that requires only a few preliminary design parameters as the input data and combines the advantages of previously published methods, resulting in a more accurate axial thrust estimation. The method is validated against previously public data from a radial pump and new experimental data from a centrifugal compressor, the latter measured at Lappeenranta-Lahti University of Technology LUT, Finland, and two gas turbines measured at Aurelia Turbines Oy, Finland. The maximum deviation between the estimated axial thrust using the hybrid method and the measured one is less than 13%, while the other methods deviate by tens of percent.
      PubDate: Wed, 24 Feb 2021 08:05:00 +000
       
  • Vibration Response of the Crawler Combine Chassis Frame Excited by the
           Engine

    • Abstract: There are many problems of vibration and noise in combine working. As the main power source and excitation source of a combine, the working state of an engine directly affects the reliability and stability of the whole harvester. In order to analyze the vibration response characteristics of a chassis frame under engine excitation, the vibration mechanism and theoretical excitation characteristics of an engine vibration source on a crawler combine harvester are analyzed in this paper, and the vibration response of chassis under engine excitation is tested and analyzed. After theoretical derivation, a two-degree-of-freedom dynamic model of an engine and chassis is established. The experimental results show that the up and down vibration generated by the engine is the main vibration source in the direction, and the main excitation frequency is the second-order firing frequency. This paper provides a theoretical reference and experimental basis for vibration reduction and noise reduction of combine and vibration characteristics of the chassis frame.
      PubDate: Sat, 13 Feb 2021 15:05:01 +000
       
 
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