Discharge coefficients of orifice-type restrictor for aerostatic bearings

The Handbook of Nonwoven Filter Media

Numerical investigation of static and dynamic characteristics of aerostatic thrust bearings with small feed holes

Numerical calculation and experimental verification of static and dynamic characteristics of aerostatic thrust bearings with small feedholes

CFD based investigation on influence of orifice chamber shapes for the design of aerostatic thrust bearings at ultra-high speed spindles

The demand of air bearings is increasing for those applications that require precision linear movements or high-speed rotations. In particular in this paper air pads for air motion technology are studied. The paper analyses the effect of a circumferential groove machined on the pad surface on pressure distribution, air flow consumption and stiffness. Two geometries are investigated and compared: one with three supply orifices and the other with a circumferential groove as well. The static characteristics of the pads are experimentally determined with also the pressure distributions under the pads along the radial and circumferential directions. The experimental pressure distributions are compared with the simulated ones, obtained with a numerical program at the purpose developed. The numerical model considers a general formulation of the supply holes discharge coefficient that can be used also in presence of a circumferential groove.

Comparison between grooved and plane aerostatic thrust bearings: static performance

An experimental study of high-speed rotor supported by air bearings : test RIG and first experimental results

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.

CFD Analysis of a Simple Orifice-Type Feeding System for Aerostatic Bearings

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.

Andrea Trivella

Papers

Discharge coefficients of orifice-type restrictor for aerostatic bearings

Comparison between grooved and plane aerostatic thrust bearings: static performance

An experimental study of high-speed rotor supported by air bearings : test RIG and first experimental results

CFD Analysis of a Simple Orifice-Type Feeding System for Aerostatic Bearings

Performance of Externally Pressurized Grooved Thrust Bearings