Experimental verification of externally pressurized gas journal bearings with asymmetric gas supply (Supply gas pressure control operation using a small size test rig)

Abstract

Experimental verification of externally pressurized gas journal bearings with asymmetric gas supply (Supply gas pressure control operation using a small size test rig) 2Ise, Imanishi, Asami, Tokumiya, Takada, Kimura and Yamaguchi, Journal of Advanced Mechanical Design, Systems, and Manufact, Vol.8, No.3 (2014) © 2014 The Japan Society of Mechanical Engineers [DOI: 10.1299/jamdsm.2014jamdsm0029] Fig. 1 Configuration of an X-ray CT gantry being more useful in terms of support of the load compared with the previously developed bearings (Okano, et al., 2006), (Ise, et al., 2007a), (Ise, et al., 2010), (Ise, et al., 2007b).We propose that this type of bearing is applicable for use in an X-ray computed tomography (hereafter called as X-ray CT) scanner gantry (Tokumiya, et al., 2013). The rotary drum of the gantry has electrical units to computed tomography scanning, as shown in Fig.1. The drum is supported by rolling contact bearing. The dynamic unbalance is roughly canceled by the arrangement of these devices. The rotary drum inner diameter is 800 or 1,000 mm and the rotating speed is 100 or 220 rpm. In present devices, rolling contact bearings are used to support the rotor. The maximum circumferential speed exceeds 11.5 m/s in present conditions. Rotation produces a somewhat unbalanced centrifugal force since the rotary drum has a small eccentricity although the unbalance is cancelled; therefore, the force due to residual unbalance with the drum mass gives to the bearings as the load. For these reasons, a large torque is required in the operation. A greater rotational speed is presently demanded of the gantry because realization of high speed rotation will result in higher precision scanning. However, a higher rotational speed results in a shorter bearing lifetime and an increase of noise, which tends to create higher patient anxiety. Radiation exposure of the patient also can be reduced by this mechanism because examination time decreases by high speed rotation. The use of the proposed gas bearings can potentially solve these problems.The final purpose is application of this bearing for the X-ray CT gantry. For this purpose, verification of the proposed bearing mechanism under the supply gas pressure control condition is first necessary. This report presents rotational tests of the proposed hydrostatic gas journal bearings with asymmetric gas supply using a small sized preliminary test rig to verify the effectiveness of the proposed mechanism. Ise, Imanishi, Asami, Tokumiya, Takada, Kimura and Yamaguchi, Journal of Advanced Mechanical Design, Systems, and Manufact, Vol.8, No.3 (2014) Working mechanism of the proposed bearingExperimental verification of the capacity of externally pressurized gas journal bearings with asymmetric gas supply (called AGS bearings hereafter) to support large load rotors was conducted. The working mechanism and the characteristics of the AGS bearing were examined by comparison with the conventional type of externally pressurized gas journal bearing. A schematic of the proposed AG...

Thermal Management and Dynamic Performance of a Cooler Design for the Supercritical CO2 Turbine Shaft Cooling

“…The externally pressurized gas bearing referred to in this verification is a rectangular slot restriction type. The actual dimensions and structure of this bearing are same as (Ise et al, 2014). The gas bearing load capacities were evaluated using the results of CFD (in this study) and test data.…”

“…Experimental and numerical investigations have been carried out on several different configurations to study the dynamic performance of gas film, such as gas foil bearings (Basumatary et al, 2020;Zhang et al, 2018;Zywica et al, 2021), self-acting gas journal bearings (Feng et al, 2017;Zhang et al, 2014), and other externally pressurized gas bearing (Moore et al, 2011;Han et al, 2014;Ise et al, 2014). Although the pressure distribution of the gas film obtained numerically with standard Reynolds equation is approximately to determine the stiffness and damping, the thermally coupled analysis of the bearing may be impeded.…”