Experimental investigation of an oscillating circular piston positive displacement flowmeter: I – Piston movement and pressure losses

Tests of an oscillating circular piston positive displacement flowmeter are described which focused on the effect on pressure drop across the meter of variation in key parameters. These included flow rate, liquid density and viscosity, mass of piston and length of connecting pipes. In addition to the average pressure loss, the pressure loss variation during the oscillation cycle was measured and found to vary with an amplitude dependent on the various parameters. A companion paper reviews data on leakage and wear.     

Exploring Operation Mechanisms of the Flexible Metal-to-Metal Face Seal: Part II—Scoring and Leakage Analysis

The numerical model previously developed in Part I was applied to analyze the contact wetness, oil exchange rate, and surface temperature distributions within the sealing band of the flexible metal-to-metal face seal (FMMFS). The analysis showed that the above three parameters were essentially critical to the seal scoring and leakage. Both macro- and microgeometries of the FMMFS contribute to variations of seal performance.     

The Real Area of Contact in Polymeric Magnetic Media—II: Experimental Data and Analysis

Electrical-contact-resistance and two-beam optical-interference techniques were employed to measure the real area of contact of magnetic tapes. The former technique does not work well due to significant contributions from tunnel effect and multimolecular insulating films; the latter provides shape and size distribution of asperity-contact areas.

Experiments were conducted at a pressure range of 13.8 kPa and 1.38 MPa. Normal pressure had strong dependence on both the real area of contact and the number of contact spots, and weak dependence on the mean asperity-contact diameter. This is in agreement with the theory. In the case of the two tapes tested in the pressure range, the real area of contact varied from 0.5 to 25 percent. The mean asperity-contact diameter and number of contact spots ranged from 6 to 13 μm and 200 to 2300 per mm², respectively. The mean real pressure was in the range of 2 to 8 MPa. The real area of contact increased with an increase in the ambient temperature. Surface roughness had strong influence on the real area of contact, as expected. Tapes subjected to pressure and temperature for a period resulted in a growth of the real area of contact. When the tapes were unloaded, a significant portion of the deformation was not recovered.     

Experimental and Numerical Study of Multibody Contact System with Roller Bearing–-Part II: Semi-Finite Element Analysis and Optimal Design of Housing

A typical roller bearing system consists of five contact parts: the housing, outer ring, inner ring, roller set, and the shaft. A finite element calculation procedure is described to analyze a five-body contact roller bearing system. If an analytical solution is used to calculate the deformations of the roller and the ring/shaft combination, a semi-finite element governing equation can be derived by simplifying the five-body contact bearing system into a three-body contact system. The semi-finite element calculation results correlate closely with the test results obtained in Part I of this paper (1). The analysis indicates that the initial gap between the housing and the outer ring and the loading positions have significant influence on the load distribution in the bearing. By optimal design of the housing, the load distribution becomes more uniform and the fatigue life of the bearing can be increased.     

Role of thermal,mechanical and oxidising treatment on structure and chemistry of carbon black and its impact on wear and friction: Part 2 – Boundary lubrication condition

Mineral oil formulations with zinc dialkyl dithiophosphate (ZDDP) and dispersant (poly isobutylene succinimide ashless dispersant or ‘PIBSA’) and fully formulated oils with and without carbon black were subjected to thermal and mechanical treatment and tribologically tested on TE 77 (high frequency reciprocating rig or ‘HFRR’) machine to examine the frictional performance during the test. These results were compared to oils without carbon black and oils with diesel soot. Results indicate that oils with just ZDDP and dispersant had the highest friction that remains constant for the duration of the test while oils with carbon black in the milled and oxidised condition had the lowest coefficient of friction and the smallest surface roughness in the tribofilm. The mechanism of wear with treated carbon black and diesel soot was found to be polishing wear as evidenced by the scanning probe microscopy images of the tribofilms. Tribofilms were analysed with X-ray absorption near edge structure (XANES) and it was seen that oils without carbon black or even with untreated carbon black had sulphates at the surface, while the oils with carbon black that were treated had a higher proportion of sulphides. A combination of both FeS and ZnS was found in the tribofilms along with short chain phosphates of Zn.     

Analysis of Double-Row Tapered Roller Bearings,Part II – Results: Prediction of Fatigue Life and Heat Dissipation

The model developed to predict the performance of double-row tapered roller bearings (DRTRB) and described in the first part of the paper is now exemplified. For a given example results on the internal load distribution, bearing fatigue life and hear generation are presented and discussed for various operating conditions including the mounting preload. It is revealed that some sliding occurs at the contact between the rollers and the cone that contributes significantly to the total power dissipated within the bearing. It is also shown that an optimum axial compression (or mounting preload) may be found in terms of fatigue life and heat dissipated. As the main conclusion the initial compression between bearing rows was found to play a major role upon the bearing behavior and therefore should be considered carefully for each application.