Journal of Engineering and Thermal Sciences
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Analysis of electromagnetic characteristic in the interior permanent magnet brushless DC motor
Get PDFThe motor vibration is mainly induced by the electromagnetic excitation. In order to improve the running performance of the permanent magnet brushless DC motor (BLDCM) within the rolling rotor compressor, this paper builds the predicted model of the electromagnetic excitation and analyzes the electromagnetic characteristic of the BLDCM. Firstly, the electromagnetic field is divided into four regions in 2D plane, including the magnet, air gap, stator slot, and slot-opening subdomains. Then, the relative equations of the electromagnetic field are constructed, and the vector magnetic potential is solved by the variable separation method. Thus, the magnetic flux density of the air gap is derived by the corresponding vector magnetic potential, which is used to describe the electromagnetic excitation. Based on the built model, the effects of the slot opening and air gap length on the electromagnetic characteristic are analyzed. The analysis results can provide a reference for the improvement of the electromagnetic characteristic of the BLDCM by structure optimization
Höegh LNG and Altera Infrastructure is scaling up large scale CCS infrastructure
Get PDFIn a joint initiative, called “Stella Maris CCS” Altera Infrastructure and Höegh LNG are working together to provide cost efficient floating Carbon Capture and Storage infrastructure solutions for a global market, not limited to size or geographical location. Valuable infrastructure experience is brought together; with FPSO (Floating Production, Storage and Offloading) and Dynamically Positioned Shuttle Tankers from Altera and FSRU’s (Floating Storage Regasification Unit) from Höegh. We intend to continue to build on our heritage and experience, using our combined skills to contribute to carbon emission reduction around globe. With the “Stella Maris CCS” project, we will essentially be doing what we are doing today, only in reverse. Our solution, initiated in 2019 as the first of its kind, will offer a large-scale floating infrastructure for collection, transport, and injection of CO2 into subsea reservoirs/aquifers. Our infrastructure concept consists of 2-3 Carbon Collection Storage Units (CCSU) to aggregate volumes at different key locations, 3-4 CO2 Shuttle Carriers and one Floating Storage and Injection Unit, the total amount of CO2 injected with these assets can reach up to 10 million tons per year. In order to realize large scale CCS, the unit costs must come down, and the barriers for emitting industries to invest in capture plants must be lowered. With Stella Maris we are addressing these hurdles. The larger ship design enables carrying volumes of CO2 at low pressure and will allow for greater economies of scale in the absence of a pipeline which places less limitations on distance to reservoir and ultimate flow capacity. Having a centralized conditioning of CO2 in a CCSO hub allows more flexibility for on-site capture design from multiple onshore industrial emission sources with shared port access. To defray high logistics cost in e.g. the Baltic region, a hub and spoke transportation approach enables collection in smaller parcels, milk-run gathering and conditioning for large scale transfer for storage in an offshore subsea reservoir on the Norwegian Continental shelf
Study on empirical model and CFD about pressure rising in Cab during door closure
Get PDFAiming at the problem that there is a strong eardrum pressure in the passenger car during the closing process, two analysis and prediction methods, fast formula prediction and CFD simulation based on accurate models, are proposed. The regression model of ear pressure comfort was established by DOE method and multiple linear regression; The simulation software star-CCM+ is applied to simulate and analyze the dynamic characteristics of the flow field in the cockpit during the closing process by using the overlapping grid technology, and the pressure change curve near the ear is obtained. Finally, the CFD numerical simulation model is established by comparing and analyzing the regression prediction analysis results and the real vehicle test data. The results show that the effects of closing speed, effective opening area of pressure relief valve and air tightness of the whole vehicle on the pressure of passengers’ eardrums decrease in turn, and the prediction error of multiple linear regression equation is 17 %; The analysis error of the internal flow field dynamic characteristic model based on refined modeling is 8 %. This study provides a theoretical basis for solving the problem of rapid prediction of eardrum pressure and optimization of engineering structure
Influence of construction technology on the retroreflective performance of two-component traffic marking
Get PDFThe construction technology of traffic marking has a significant influence on its retroreflective performance. To study the effect of different construction processes on the service performance of traffic markings, two-component spraying paint and two different glass beads were chosen to produce traffic markings that were prepared by single-layer or double-layer spraying, as well as once and twice surface spraying of glass beads. The effects of glass bead coating, spraying times of glass beads and paints on the surface morphology and retroreflective performance of traffic markings were investigated, as well as the variation of the retroreflective coefficient (RC) at the early and middle stages. The results indicated that double-layer spraying was more effective than single spraying. The coated glass beads would decrease the initial RC of the markings, but improved their long-term service performance. The TP-21C has the finest overall retroreflective performance and the lower construction complexity
Hierarchical dispersion entropy and its application in fault diagnosis of rolling bearing
Get PDFAiming at the disadvantage that multi-scale entropy only analyzes the low-frequency components of time series, this paper proposes a rolling bearing fault feature extraction method based on hierarchical dispersion entropy (HDE). Firstly, the HDE is constructed based on the hierarchical operators and dispersion entropy. Secondly, the influence of HDE parameters on entropy stability is studied. Finally, the fault diagnosis method based on HDE, least square support vector machine is applied in rolling bearings. The experiment results show that the proposed method can distinguish different types of the rolling bearing faults. It owns the higher fault diagnosis accuracy than the traditional multi scale entropy methods, such as multi-scale sample entropy (MSE), multi-scale dispersion entropy (MDE)
A review for the noise source identification methods based microphone array
Get PDFSound source identification is an important prerequisite for noise control. In recent years, new methods of sound source identification have been developed to improve the robustness of source identification. In this paper, a comprehensive review of noise source identification methods is developed to summarize its developing status and engineering applications. At first, a microphone array which is to acquire the sound pressure field is described. And then, the sound field visualization methods (beamforming and acoustic holography) and their advantages and disadvantages are reviewed. Finally, to improve the identification accuracy of the moving sound source, the hybrid acoustic holography methods with more generality and robustness are reviewed. Through the comparison and summary of the sound source identification methods, we expect this work may provide a potential guidance for the subsequent research studies in the field of sound source identification
The discriminant statistic based on MPE-MWPE relationship and non-uniform embedding
Get PDFThe slope fitting line between MPE (multi-scale permutation entropy) and MWPE (multi-scale weighted permutation entropy) is recently proposed as a discriminant statistic for testing the nonlinearity of a time series. The main objective of this paper is to demonstrate that the selection of the optimal parameters of the non-uniform embedding is essential for the proposed discriminant statistic. In particular, the presented case studies indicate that the modified discriminant statistic based on non-uniform embedding can detect differences between such time series which remain indistinguishable if the original approach is used
Damping transformation modeling on wheel suspension using pneumatic cylinder thrust force as a substitute for vehicle weight
Get PDFThis study aims to produce a vertical dynamic load transformation model, FDV of medium weight vehicles that burden the road structure, the form of suspension work characteristics on vehicle wheels that experience disturbances and vertical loading, and the relationship between vehicle vertical dynamic loads and road structure strength, FA0 in the form of a dimensionless parameter. The experiment was carried out at the Pneumatic and Hydraulics Laboratory of the State Polytechnic of Ujung Pandang using pneumatic actuators as a substitute for vehicle weight. The dynamic load fluctuation of the medium weight category vehicle is equivalent to a pressurized air setting from 1 bar to 6 bar which puts a direct load on the suspension system on the vehicle’s wheels. The deviation, Y (cm) that occurs when there is compression on the Spring and Shock Absorber can be measured using a distance sensor, while the vertical dynamic load, FDV which burdens the road surface using a Load Cell. The data were analyzed using the vehicle dynamic load equation with pressure variable, P2 (bar), spring constant, k2 and damping fluid coefficient, c. A mathematical study of the vibration characteristics of the vehicle suspension was obtained using the Mat Lab program. The results showed that the vibration characteristics of the vehicle body experienced an overshot at a deviation of Y is 0.534 m for 0.131 seconds. The role of the shock absorber in the suspension mechanism can reduce 26.43 % of the vertical dynamic load FDV (N), and in the time interval, t is 3 seconds with acceleration deviation, is 0.25 m/s2 begins to feel comfortable. The relationship between vehicle dynamic load, FDV and road structure strength, FA0 is 0.0178. The data from the comparative analysis is then recommended as a consideration for road construction planners to determine the strength and service life of the road
Modal analysis of spur gears for varied teeth root cracks characteristics: finite element analysis (FEA) simulations
Get PDFGear failure is considered the main alarming and undesirable event in gearboxes. Usually, cracks happen by fatigue caused due to cyclic loading. Fatigue stress is focused on the teeth root because of the small tooth fillet radius. This causes progressive damage to gear teeth which causes teeth failure, and hence, a damaged gear. This work shows a numerical framework to identify and quantify cracks' existence at the teeth root of spur gears. The problem is numerically analysed through finite element-based simulation with ANSYS by conducting a modal analysis. There are nine cases of gears with different cracks on their tooth; these cracks are varied by their number (single or multiple), Crack Length Percentage (CLP %), and location. The FEA is used to simulate all nine cases to predict the bending natural frequency of teeth and to investigate the effects of the variation of the crack by looking at the natural frequency of the teeth bending as well as the deformation level. Results revealed that the teeth bending natural frequency decreases as the CLP% increases. In addition, the gear stiffness is calculated based on the natural frequency and gear’s mass and it is indicated that the stiffness decreases as the CLP% increases, while the deformation level increase with CLP%
Numerical simulation of cross-hole deburring by abrasive flow in a three-way hole
Get PDFThe SST k-ω method is used to numerically simulate the effect of the inlet pressure and processing method on the machining of a three-way hole, revealing the effect of dynamic pressure and wall shear on the machining of the grain flow with different processing parameters. The simulation results show that increasing the inlet pressure and choosing a suitable processing method can improve the processing effect of abrasive flow processing