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Analysis of airgap magnetic field is the basis of design and performance analysis of permanent magnet (PM) motors. Based on 2D models in polar coordinates, the analytical formulas of the open-circuit airgap flux density in PM motors equipped with parallel magnetised magnets are derived by solving the Laplace's equation or Poisson's equation in the regions of airgap, PM and shaft core. And based on...
Evaluating the high cycle fatigue (HCF) and the thermal mechanical fatigue (TMF) is a critical aspect of the heavy duty gas turbine blade design and manufacture. But the highly accelerated stress screening (HASS) method can be used to assess the high cycle fatigue life of the blades and the manufacturing process defects. In this paper, an electromagnetic resonant device is designed to test HCF and...
In this research, a low cost control system of active magnetic bearings (AMB) has been designed and implemented using LabVIEW Interface for Arduino (LIFA). This study consists of analog signals acquisition, converting the analog signals into the digital signal (ADC), digital data processing, drawing real-time curve and historical curve of signals, pulse-width modulated (PWM) drive and PID control...
In this paper, a new method is used to study the static characteristics of sliding bearings. The solving method and the process are expounded. Firstly, the validity of the new method is illustrated in mathematical form. Then the correctness of the method is verified by comparing the results with literature. With the help of Ansys, this paper put forward a new way to use the Reynolds boundary condition,...
The turbine blade is the most important component in the heavy-duty gas turbine. The common fatigue failures of the blade include the thermal fatigue and mechanical fatigue. Firstly, the finite element simulation of the blade is carried out in the working condition including the centrifugal load, high frequency vibration load and thermal load. According to the simulation results of the combined load,...
The rotor system, as a core component of a rotating machine, has a direct impact on the performance, longevity and stability of the entire rotating machine. In engineering, most of the rotating machinery faults are caused by the bad vibration of the rotor, so the study of rotor vibration characteristics has been a hot issue in rotor dynamics research. However, in engineering applications, processing...
Interference fits, which are widely used in the high-speed couplings of micro gas turbines, can transfer large torques while avoiding unbalance. Elastic limit pressure is an important parameters for determining the maximum load capacity of high-speed couplings of rotating elastic interference fits. In this paper, we developed a model to study the dependence of the maximum load capacity of rotating...
A trunnion joint is modeled as a circular plate with a rotational spring at the outer peripheral portion to resist rotation. Asymmetrical bending deflection is produced when an external moment acts on the inner side of the circular plate. The equations of the circular plate with a special outer peripheral boundary condition are derived. Choosing the stiffness of the rotational spring and the ratio...
The wave journal bearing was first reported by Dimofte In the early 1990's. The static behavior of a hydrodynamic wave journal bearing is present in this paper. It is found that the static performance is related to the design parameters including eccentricity ratio, wave number, wave amplitude ratio and wave position angle. It is shown by the numerical results that the influence of the wave number...
Due to the very small gap of the contact relaxation, which is attributed to the abrasion of blade shrouds in the gas turbine, the fatigue failure of the blade occurs severely. So the gap effect and the high cycle fatigue properties of the turbine blade need to be studyed. Based on the theoretical calculation, the equation of the maximum value of shroud gap is given. Then through the finite element...
Bolted joints is widely used in mechanical Engineering. The interface formed by two members in contact represents thermal contact resistance to flow of heat from one member to another. As a result, temperature difference occurs at the contact interfaces of the joints while the bolts still have a continuous thermal distribution through the joints. The consistent thermal distribution between bolts and...
In recent years, non-circular journal bearings are widely used in industry on account of their better stability, simplicity, efficiency and low cost. In this paper, an elliptical bearing neglecting the journal eccentricity is investigated. The results show that the oil-film thickness can always be expanded into a Fourier series. And the basis function of the series is just related to the total amount...
Ultra-high-speed permanent magnet synchronous motors (PMSMs) usually use bipolar rotors with ring permanent magnets (PMs) or cylindrical PMs which are magnetised in parallel. The stator of the motor is first simplified as a slotless stator, and an analytical solution to the flux density distribution in the motor is obtained by solving the Laplace's equation in the regions of PM and airgap. Then, by...
An analytical model is proposed using the d/q-axis model to estimate the maximum output power of the high speed permanent magnet synchronous generator (PMSG) and corresponding current, power-angle, etc. An experimental phenomenon that a 100kW 45000rpm PMSG unable to generate rated power is analysed using the analytical model. Then the rotor structure is improved according to the analytical results...
The rotordynamic characteristics of a simulated rotor system supported on gas foil bearings was investigated, which has a rated speed of 24 krpm. A test rig was established and assembled to simulate the operating performance of the rotor system for a microturbine. The compliant gas foil journal and thrust bearings were designed to support the rotor. The rotor system was driven by high pressure gas...
Gas turbine rotor works at high temperature, especially the turbine used to expand hot gas and generate power. Temperature may change the elastic modulus of the material as well as cause thermal stress of the gas turbine rotor. Both of these two factors can cause a local stiffness variation of the rotor assembly and thus have an influence on the dynamic characteristics of the rotor. The rotor investigated...
For the ultra high speed PM rotor, a metallic sleeve is usually interference fitted onto a cylinder or ring shaped PM to against the huge centrifugal force. The initial interference hinges not only on the loose of the rotor, but also strongly on the strength of the PM and the sleeve. In order to determinate the initial interference, this paper proposes an analytical model of stress/displacement field...
Gas Foil Bearings (GFBs) are self-acting hydrodynamic bearings and potential alternatives to rolling element bearings for high speed applications. In order to increase load capacity, the assembly preload is often added to GFBs now. Firstly, for multi-leaf GFBs with assembly preload, this paper presents a method to fabricate the bearings with assembly preload, and the precision of the shape of the...
With the popularization and development of science and technology, especially in the field of high speed machine tool, the compressor and the micro gas turbine system, the traditional motor can't fit these requirements. Because of its high speed,supreme power density and obvious efficiency advantages, high speed permanent magnet synchronous motor (HSPMSM) is developed and its application has entered...
In the last years, heavy-duty gas turbine has been increasingly used as high efficiency systems for heat and power generation. The typical size of these powerplants mainly consist compressor, turbine and combustor. And the rotor disc assembly structure is different from the single whole rotor structure. Several computer codes have been developed to analyse the strength of the rotor. In the present...
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