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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,...
Magnetic bearings are oil-free bearings that are widely employed in rotating machineries such as high-speed motors in order to eliminate lubrication systems, reduce wear, increase efficiency and mechanical service life. Based on a high-speed motor with a power of 5 kW and a maximum speed of 60 000 rpm, active thrust magnetic bearings are designed to match with the high-speed motor considering the...
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...
The combined circumferential tie rod rotor with the advantages of light weight, good cooling effect and easy assembly is widely used in gas turbines, especially in heavy-duty gas turbines. In this paper, a circumferential tie-rod combined rotor was investigated using two-dimensional finite element model and three-dimensional finite element model with ANSYS. The critical speed of the rotor were calculated...
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...
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...
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...
Disc-rotor has the advantages that the common continuous rotor doesn't have, but the specific structure of the disc-rotor makes it complex to compute the natural frequencies and vibration modes. It is mainly reflected in that the discs contact each other, which will bring considerable impact on the dynamic behavior of the disc-rotor. The state of contact between the discs is closely related rod preload...
Although aerodynamic compliant foil bearings are successfully applied in a number of turbo-machineries, theoretical researches on the modeling, performance prediction of compliant foil bearings and the dynamic analysis of the related rotor system seem still far behind the experimental investigation because of structural complexity of the foil bearings. A generalized solution of the elasto-aerodynamic...
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