Performance of Externally Pressurized Grooved Thrust Bearings
TL;DR: In this paper, externally pressurized grooved gas thrust bearings for shaft systems were studied both numerically and experimentally, and the influence of a circumferential groove situated in correspondence with the supply holes was discussed.
Abstract: Externally pressurized grooved gas thrust bearings for shaft systems were studied both numerically and experimentally. Three thrust bearings composed of a symmetric pair of rings facing a shaft collar were tested. The rings, with inner and outer diameters of 52 and 110 mm, respectively, are equipped with a polar array of eight holes, with a 0.35-mm diameter, distributed on a 65-mm-diameter circumference. The influence of a circumferential groove situated in correspondence with the supply holes is discussed. In particular, two thrust bearings have a rectangular cross-sectional groove of 0.7-mm width and 10- and 20-μm depth. A numerical model based on Reynolds' equation is used to study thrust-bearing performance in relation to geometry (diameter of supply holes, clearance, and groove dimensions). A test rig is used to monitor thrust-bearing axial load capacity and stiffness, and evaluate damping and stability at different supply pressure rates. Experimental and numerical results are compared and discussed.
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TL;DR: A review of the state-of-the-art in aerostatic bearing research and development with the emphasis on analytical and computational approaches for design and optimization of bearing performance is presented in this paper.
83 citations
TL;DR: In this article, the influence of structural parameters of pressure-equalizing grooves (PEGs) such as length, depth, number and location on the load capacity and stiffness are studied systematically.
57 citations
Additional excerpts
...[19] studied the aerostatic thrust bearing with the circumferential groove of the different depths....
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...The flow rate through 1st orifice after opening the PEG will increase due to the decrease of gas film impedance [19], which makes the outlet pressure of 1st orifice with PEG less than that without opening PEG at the same eccentricity ratio....
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TL;DR: In this paper, a numerical analysis on the feeding system of externally pressurised gas bearings, for the correction of the theoretical mass flow rate formula by means of a discharge coefficient, is presented.
Abstract: A numerical analysis on the feeding system of externally pressurised gas bearings, for the correction of the theoretical mass flow rate formula by means of a discharge coefficient, is presented. A flat aerostatic pad with a simple orifice-type feeding system was chosen as case on study, the authors having previously carried out experimental tests on such a prototype. Using the commercial CFD code ANSYS Fluent®, preliminary simulations were carried out on a pad’s geometry using three different flow models. Having selected the flow model able to give the best prediction of the pad’s behaviour in terms of pressure distribution along the air film, additional simulations were carried out on pads with two different diameters of the supply hole, varying the film thickness in a range from 9 to 14 μm. A comparison between numerical and experimental results is presented. In addition, the effect of the flow intake used to perform experimental tests and of the shape of the orifice’s external edge on pressure distribution is analysed.
35 citations
Cites background from "Performance of Externally Pressuriz..."
...Usually, simple orifice-type or pocketed orifice-type restrictors are used as supply systems [1]; in both cases, measuring the supply holes’ downstream pressure and the pressure distribution along the air film is fundamental for predicting air pads behaviour [2, 3]....
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TL;DR: In this paper, a numerical model was established to investigate the influence of operating conditions, geometric parameters and manufacturing error on the angular stiffness of aerostatic bearings with orifice restrictor.
26 citations
TL;DR: In this paper, a simplified performance calculation method of aerostatic thrust bearing with multiple pocketed orifice-type restrictors is presented, which explains theoretically the influence of film thickness, orifice diameter, gas property, supply pressure and structural parameters on the bearing's performance.
20 citations
References
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TL;DR: In this article, an experimental study conducted in order to determine the supply hole discharge coefficients of externally pressurized gas bearings was conducted, where air consumption and pressure distributions were measured as a function of supply pressure and air gap height for several different orifice and pocket sizes.
120 citations
Patent•
27 May 1975
TL;DR: In this article, the spiral grooving of a thrust-plate of an aerodynamic gas-lubricated bearing is formed by ionic bombardment of a flat face of a machined blank.
Abstract: The spiral grooving of a thrust-plate of an aerodynamic gas-lubricated bearing is formed by ionic bombardment of a flat face of a machined blank. The face is masked to leave exposed only those areas where material is to be removed. Grooving on a cylindrical surface of a spindle is similarly formed, the cylindrical blank being rotated to present the unmasked areas successively and repeatedly for bombardment.
98 citations
TL;DR: In this paper, the performance of an aerostatic thrust bearing with pocketed orifice-type restrictor was analyzed and the rational dimension of this kind of bearing was obtained by analyzing the influences of the bearing's geometrical parameters on its load carrying capacity (LCC), stiffness, mass flow rate (MFR) and the maximum gas velocity (MGV).
95 citations
TL;DR: In this paper, a finite element method enabling the Reynolds equation solution for any face geometry of gas thrust bearing or of gas seal is presented, which reduces the thickness discontinuities by integration by parts of the terms involving derivatives.
Abstract: A finite element method enabling the Reynolds equation solution for any face geometry of gas thrust bearing or of gas seal is presented. Difficulties due to thickness discontinuities are reduced by integration by parts of the terms involving derivatives. The weak form of the finite element Reynolds equation is then solved and the nonlinearity of the equation leads to the use of Newton-Raphson procedure. The process is fast convergent. The problem of oscillating solution is solved by the use of an upwind procedure. Some numerical examples show the accuracy and efficiency of the procedures. It is shown that the developed finite element program provides a numerical tool, more efficient than the method used until now, for the grooved gas seals design. 16 refs.
81 citations
TL;DR: In this paper, the resistance network method was used to design an aerostatic rectangular bearing with X-shaped grooves, and the Newmark integration method and the modified RNM, which took into account the equilibrium of the mass flow rate and the squeeze film effect, were used to analyze the timedependent dynamic behaviors at each time step.
65 citations