Purpose




The purpose of this study is to analyze the influence of high-temperature inlet oil on the comprehensive performance of tilting-pad bearing.




Design/methodology/approach




Taking a tilting-pad bearing under high temperature of inlet oil in a natural gas compressor as an example, the experimental system was developed for the tilting-pad bearing applied in a real machine, and the experiment was performed. The bearing lubricating properties under different high temperatures of inlet oil were obtained, including oil film thickness on the pivot, temperature rise and the shaft vibration values at the bearing positions.




Findings




The experimental results showed that the vibration, the oil film thickness on the pivot and the pad temperature were not sensitive to the change in temperature of the inlet oil, but vibrations were observed under the specific speed. At the same speed, when oil temperature changed by 1°C, the bearing temperature rise did not exceed 0.2°C and change in oil film thickness on the pivot was 1 µm. The test results of the actual unit are in good agreement with the experimental results.




Originality/value




The vibration measurement scheme was presented, and an indirect measurement method of fulcrum thickness was proposed. The practicability of the measurement method and the accuracy of test results were verified by the comparison of the test results of the shaft vibration, the bearing pad temperature, the fulcrum oil film thickness and the theoretical calculation results. This study will provide an important reference for designing a tilting-pad bearing with high-temperature inlet oil.

Experimental research on the tilting pad bearing under the high temperature of inlet oil

Proposing a new type of water-lubricated thrust bearing meets the load-bearing requirements of high-power shaft-less rim driven thrusters.,The designs were tested by establishing a bearing thermal-fluid-magnetic comprehensive simulation model and developing bearing fluid film force and magnetic simulation. Lubrication performance tests were carried out on the bearing test rig.,The Halbach array of magnet blocks is able to reach the maximum magnetic force. The material of sheath can help increase the magnetism. The magnetism is able to reduce wear during low-speed and the start-stop phase, while the eddy current loss at high speeds will lead to a decrease in magnetic force. The experiment found that the bearing was more stable at low speeds and would not demagnetize due to the temperature rise, but it is necessary to pay attention to the running stability at high speeds to prevent rubbing and impact.,An innovative combination of hydrodynamic pressure and permanent magnetic repulsion was observed to form a magnetic-liquid double suspension bearing with large bearing capacity.,The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-08-2020-0295

Load carrying capacity of a novel magnetic-liquid double suspension fixed pad thrust bearing

Numerically simulating lubricated components is a basic analysis method in tribology. Such kind of simulation usually requires solving a closed equation system. Iterative algorithm has been used to numerically solve it for many years. The convergence of the corresponding solution procedures is achieved by adjusting some initial parameters to satisfy the pre-defined convergence criteria. There is very little discussion about the method used to adjust the initial parameters, however it directly influence the convergence of the whole simulation. In this paper, the analogy between the solution procedures and the feedback loop was discussed. And based on such analogy, the widely used proportional-integral-derivative controller (PID controller) in the control of the feed-back loop could be also used to make the solution procedures of lubrication simulation converge. The mixed point contact EHL problem, which is rather difficult to converge in lubrication simulation, was chosen as the example to prove the validity and efficiency of using PID controller in the solution procedures. The results show that the PID controller can be easily implemented and simplify the code. And it really accelerates the convergent speed of the simulation. In some working conditions, the traditional way cannot lead to satisfied results but the PID controller can make it. The most attractive advantage of using PID controller is that it can automatically converge the solution procedure, no extra modification is needed once the simulation starts.

A method for improving the capability of convergence of numerical lubrication simulation by using the PID controller

Tilting-pad thrust bearings are widely used in high-speed and heavy-load rotor-bearing system. Measurement of the oil film thickness distribution is vital important for understanding bearing’s lubrication condition. However, this remains a challenge because the oil film normally locates in the enclosed space and has a very tiny scale. Here, a tilting-pad thrust bearing rig with six pads is built and the ultrasonic methods are used to measure the oil film thickness distribution and further obtain the gesture of the tilting-pad thrust bearing. Eight piezoelectric elements are bonded on the back of one pad of the thrust bearing, making the pad similar as a smart bearing. The oil film thickness of each gauging point is obtained by the characteristic of the reflected sound. Then both the oil film thickness distribution and the gesture of the pad are obtained by fitting the measured values via least square fit. The influences of the vibration, load and rotor speed on the oil film thickness distribution are then investigated. The results agree well with the ones obtained by the eddy sensors. This work presents a promising non-invasive method to measure the oil film thickness distribution in tilting-pad thrust bearings.

Experimental Measurement of Oil Film Thickness Distribution in Titling-Pad Thrust Bearings by Ultrasonic Piezoelectric Elements

Study on transient performance of tilting-pad thrust bearings in nuclear pump considering fluid-structure interaction

Purpose – The purpose of this paper is to analyze the problems of tilting-pad thrust bearing static instability and lubrication performance under static bistability. Design/methodology/approach – The static equilibrium state of tilting-pad thrust bearing is analyzed, and key parameters are extracted from the general lubrication model. Then, a distribution area of bearing static equilibrium points is achieved by solving the model. The area is divided into three sub-areas which represent monostabillity, bistability and instability, and an unstable boundary of the area is discovered. By these findings, a reversible lubrication failure phenomenon is explained. A calculation method is proposed to obtain bearing lubrication performance under the bistability. Findings – The variation of working conditions can lead to migration of unstable boundary and static instability. After resuming the working conditions, unstable boundary will resume in situ, and the bearing will operate steadily again. Moreover, there is a...

Ouyang Wu

Papers

Analysis of tilting-pad thrust bearing static instability and lubrication performance under the bistability