Search results

1 – 4 of 4
Per page
102050
Citations:
Loading...
Access Restricted. View access options
Article
Publication date: 3 May 2016

Mukesh A. Bulsara, Anil D. Hingu and Pratik S. Vaghasiya

One of the major problems faced by industry is vibrations in rotating parts. Vibration is a to-and-fro movement of rotating mechanical parts and has many detrimental effects on…

301

Abstract

Purpose

One of the major problems faced by industry is vibrations in rotating parts. Vibration is a to-and-fro movement of rotating mechanical parts and has many detrimental effects on machinery. It is obvious that no movement can be achieved without consumption of energy. All the energy consumed in vibration of mechanical parts is useless. Unbalance is one of the most common reasons for vibrations. This paper aims to experimentally evaluate the effect of unbalance in a shaft–rotor system on power consumption. An experimental setup consisting of a shaft and a rotor mounted on antifriction bearing was built-up. The shaft was driven through a flexible coupling, by a variable speed DC motor. The shaft–rotor system was rotated at different speeds and electrical power consumed by the system was measured at specific speeds varying from 1,200 to 2400 rpm. The rotor was balanced to grade G6.3 at 1,200 rpm. The power consumption by shaft in balanced condition was taken as baseline data for the further work. The rotor was then made unbalanced by adding different masses at 60 mm radius, and power consumption was recorded again at the same speeds. It was observed that average power loss due to unbalance is of 0.11watt/gm.mm unbalance. This can amount to 2.75 kw if there is unbalance of 50 gm at a radius of 500 mm. This work is meant to emphasis on the fact that the power consumption can be reduced if the vibrations can be kept under control.

Design/methodology/approach

The experimental setup consisting of a rotor–shaft system was fabricated. The shaft was supported on two anti-friction bearings. The shaft is driven by a 0.25 HP DC motor. The speed of the motor can be varied by a speed controlling device. A digital ammeter and voltmeter are connected to measure the input current and voltage to the system. The rotor was rotated at different speeds after two-plane balancing and the parameters like voltage, current drawn, rms velocity (average of drive and non-drive side bearing) and displacement at 1× frequency were recorded. The base line data for the balanced shaft–rotor system were recorded for further use.

Findings

Power consumption increases with increase in unbalance at each of the speeds. Total power consumed at resonant frequency is high. The average power consumed “W/gm.mm” increases at higher speed due to increased damping force of lubricant in bearings combined with the effect of resonance. Average power consumed due to unbalance is about 0.11 W/gm.mm unbalance. It is important to reduce the vibration to save power which can be effectively achieved by balancing the rotating parts in the machinery.

Research limitations/implications

The experimentation is done on a small rotor. When the same work is done on real situations where the rotors are heavy, we may expect some differences in the actual effect of unbalance on the power consumption.

Practical implications

The experimental work have a huge application in industry in condition monitoring. The power may tend to increase not only because of the unbalance but also due to other reasons of vibrations like misalignment, loose foundation, poor bearing conditions, etc. The power loss may increase due to any other reasons mentioned above. The degree of power saving due to steps taken for reducing vibration will depend on the existing vibration levels.

Social implications

The work highlights the effect of power loss due to vibrations. Even (1 per cent) small amount of power saved can save millions of dollars in industry, as there are many rotating parts which run 24 × 7. The emphasis is on condition-based monitoring which will help in power saving beyond the conventional advantages of condition monitoring.

Originality/value

The experimentation clearly quantifies power loss in absolute form that is the power loss is expressed per gm.mm of unbalance and not as the percentage of electrical or mechanical power, input or output. The percentage values may be misleading some times, as SMALL percentage of large values is also LARGE and hence should be taken into consideration.

Details

Journal of Engineering, Design and Technology, vol. 14 no. 2
Type: Research Article
ISSN: 1726-0531

Keywords

Access Restricted. View access options
Article
Publication date: 16 September 2013

Mukesh A. Bulsara, Dhananjay V. Bhatt and Kishore N. Mistry

The purpose of this paper is to present a measurement technique wherein the film thickness is measured in unfired condition for entire stroke length but without impairing the…

464

Abstract

Purpose

The purpose of this paper is to present a measurement technique wherein the film thickness is measured in unfired condition for entire stroke length but without impairing the original condition of piston ring, liner and lubricant, i.e. non-invasively. Film thickness is measured at different speeds up to 500 rpm. The measurements are initially carried out at near zero speed followed by speeds mentioned above. Measurement highlights the combined effect of variation of bore diameter and ring face profile on the film thickness.

Design/methodology/approach

The film thickness is measured with the help of a set of strain gauges. Four strain gauges are mounted on a sufficiently elastic steel strip which is mounted in a simply supported condition. This assembly of strain gauge is mounted on small rectangular bracket. A cutout is made in the piston to accommodate the bracket. A pin bearing a slot of size sufficient enough to accommodate the piston ring on one side is fixed between the piston ring and the strain gauge assembly. This ensures the transfer of the movement of the piston ring on to the strain gauge. The deflection of the strain gauge is pre-calibrated against a sufficiently accurate dial gauge. Hence any radial movement of the piston ring is sensed by the strain gauge assembly. A data logger unit is connected to the strain gauge output to log the data at every crank angle. A rotary encoder is connected to the crank shaft, to have the correlation of the strain gauge output with the crank angle.

Findings

The technique is capable of measuring oil film thickness for entire stroke at low speeds in unfired engines. The effect of variation in bore diameter on the oil film thickness is significant and hence such measurement can enlighten the path for research to reduce friction. The experimental results of the oil film thickness are in good agreement with predicted values, particularly in the forward stroke (BDC to TDC).

Research limitations/implications

The methodology is not suitable for fired engines as on date but can be taken up as a future work with necessary modifications. It does not take into consideration the effect of elasto-hydrodynamic lubrication.

Practical implications

It can be used to measure OFT between piston ring and liner in unfired engines and reciprocating compressors also.

Social implications

It can help to indentify the areas of research so that the friction between piston ring and liner can be reduced thus increasing efficiency of the engine and reducing fuel consumption and emissions.

Originality/value

The work presented is a part of PhD work under progress at S V National Institute of Technology, Surat, India. The setup is in the college premises and the experiments are conducted on the same.

Details

Industrial Lubrication and Tribology, vol. 65 no. 6
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 9 August 2013

Mukesh A. Bulsara, Dhananjay V. Bhatt and Kishore N. Mistry

The aim of this paper is to develop a technique to measure the oil film thickness between piston ring and liner throughout the stroke, without impairing the surface properties of…

380

Abstract

Purpose

The aim of this paper is to develop a technique to measure the oil film thickness between piston ring and liner throughout the stroke, without impairing the surface properties of the piston ring and liner. Mechanical properties of the piston ring, like ring stiffness, are also not altered. Effect of variation in bore on the movement of piston ring can be studied with the proposed technique.

Design/methodology/approach

The gap Hmin between the cylinder liner and the piston ring is formed due to the hydrodynamic pressure generated by the presence of oil film between piston ring and liner. This gap can be inferred by measuring the movement of the inner surface of piston ring with reference to a sensor mounted on the piston at a fixed distance from the piston ring. The piston ring is connected to the sensor through reasonably rigid member. The underlying assumption here is that there is no elastic deformation of the piston ring due to the hydrodynamic pressure. The fundamental sensor to measure oil film thickness used in this setup is a set of strain gauges.

Findings

It is possible to measure oil film thickness by the proposed arrangement for the entire stroke without changing the surface properties. Mechanical properties of the piston ring, like ring tension, are not affected. The results possibly provide the correct picture of the piston ring movement throughout the stroke. The measurement at near zero speed can give information on the movement of the piston ring due to hydrodynamic action and to the variation in the bore. The measurement is not affected by engine vibrations. The proposed technique can be helpful in validating the theoretical models proposed in the literature.

Originality/value

The measurement is possible only in unfired condition. However, this attempt can be considered as the basis to measure OFT in fired condition with necessary improvements. It is not feasible to measure quantity of lubricant/extent of lubricant on leading or trailing edge of piston. Effect of temperature on the oil film thickness cannot be studied as the engine is not fired. It is assumed that the piston ring does not pass through elasto‐hydrodynamic lubrication regime. Debris/worn out particles in the oil may affect the indicated oil film thickness at local points.

Details

Industrial Lubrication and Tribology, vol. 65 no. 5
Type: Research Article
ISSN: 0036-8792

Keywords

Access Restricted. View access options
Article
Publication date: 2 July 2020

Dinesh Shinde, Mukesh Bulsara and K.N. Mistry

The purpose of this paper is to evaluate experimentally the influence of different surface roughness of the contacting disc on tribological performance of the non-asbestos brake…

190

Abstract

Purpose

The purpose of this paper is to evaluate experimentally the influence of different surface roughness of the contacting disc on tribological performance of the non-asbestos brake friction material (BFM).

Design/methodology/approach

Taguchi method was applied to design an experiment using three different discs of gray cast iron with different surface roughness, which is measured using optical profilometer. These discs were subjected to sliding against pins prepared with the developed non-asbestos BFM, using pin on disc friction and wear monitor.

Findings

The experimental results shows that the disc 2 (Ra = 3.77 µm) gives wear of 22.78 µm and coefficient of friction of 0.462, which is recommended for extreme brake performance. Analysis of Taguchi design revealed that the disc surface was most significant parameter among the parameters under study.

Practical implications

During braking, continuous sliding between the BFM and brake disc or drum not only results into wear of BFM but also changes the surface finish of the brake drum or disc. This leads to variation in surface topography of the drum or disc surface with application of brakes, which further affects the characteristics of the BFM.

Originality/value

The tribological performance of BFM depends upon the topography of the surface on which it was sliding. To get best performance of the non-asbestos friction materials, disc having moderate surface finish is recommended. Scanning electron microscope micrographs had shown the different plateaus formed and energy-dispersive X-ray spectroscopy spectra identified presence of different chemical elements prior to sliding of the pins surface over different discs surface topography.

Peer review

The peer review history for this article is available at: https://publons.com/publon/10.1108/ILT-04-2020-0120/

Details

Industrial Lubrication and Tribology, vol. 72 no. 10
Type: Research Article
ISSN: 0036-8792

Keywords

1 – 4 of 4
Per page
102050