Comparative Performance of a Non-recessed Hole-entry Hybrid/Hydrostatic Conical Journal Bearing Compensated with Capillary and Orifice Restrictors

This research paper deals with the theoretical study of comparison of capillary and orifice compensated non-recess hole-entry hydrostatic/ hybrid conical journal bearing. Modified Reynolds equation governing the flow of lubricant in the clearance space of conical journal and bearing has been solved using FEM, Newton-Raphson method and Gauss elimination method. Spherical coordinate system has been employed to obtain the results. The results have been computed for uniform distribution of holes in the circumferential direction with the range of restrictor design parameter C ̅_s2 = 0.02 - 0.1. The numerically simulated result shows, the use of orifice restrictor is to increase bearing stiffness, threshold speed and maximum pressure compared to capillary restrictor for applied radial load

Effect of Tapered Interference Fit between Impeller and Shaft in Turbo Machines

In Turbo machines, there are many components which are provided with interference to transmit torque and to maintain contact between them. There are transient scenarios where impeller and shaft lose interference and limits the speed of the impeller. In this paper, a case study on centrifugal compressor has been presented to see the effect of taper pairing of shaft with impeller. When the centrifugal compressor starts then a transient condition is dominant wherein the impeller of the centrifugal compressor gains higher temperature quickly compared to shaft. Since the thermal expansion of the impeller will be much more than the shaft, interference between impeller and shaft is likely to reduce. With reduced interference, the impeller should retain minimum required contact pressure with the shaft and the torque transmitting capability. For conventional fitted impeller, stress built up is a major concern especially at higher speeds. This paper gives a proposal about the importance of tapered interference fit method compared to cylindrical fitted impeller assembly. An effective analysis between the conventional straight fitted impeller and impeller having tapered bore is presented for the same torque transfer capability. The analysis reveals that for the impeller with tapered bore, the stress for impeller reduces and a healthy contact pressure exists

Comparative Frictional Analysis of Automobile Drum and Disc Brakes

In the present work, a comparative frictional behaviour of drum brakes and disc brakes in automobiles has been investigated. The influential factors; contact force and friction radius were modeled for the estimation of the friction coefficient for drum as well as disc brakes. The effect of contact force and friction radius is studied with varying conditions of parameters; longitudinal force, caliper force and torque on piston side as well as non-piston side. The numerical results obtained have been compared with the similar obtained from virtual Matlab/Simulink models for drum and disc brakes. The results evidenced that friction radius predominantly affects brake pressure and thus the friction coefficient, also the increase in contact force resulted with decrease in friction coefficient both for drum and disc brakes. Further it has been found that disc brakes exhibit gradual decrease of friction coefficient due to the equitable distribution of braking effort while drum brake presents sudden variations in friction coefficient. It can be revealed that frictional behaviour of disc brake is more consistent than drum brake