The imbalance of a rotating machine part may cause harmful vibrations in the entire machine. A familiar example is unbalanced tyres on a car. In rotating machines such as turbines or pumps, vibrations due to imbalance lead to comfort problems or even damage related to overloading. If this balancing is done not on a particular machine but directly on the machine in operation located on-site, it is known as field balancing. These cause annoying and unpleasant vibrations in the steering. This is why almost all rotating parts are balanced.
Learning Objectives And Experiments:
Measure and assess machine vibrations
Static, dynamic or general imbalance
Occurrence of imbalance vibrations
Field balancing in one plane
Field balancing in two planes
Dependence of imbalance vibration on position and magnitude of the imbalance
Basic principles of balancing
Using a computerised vibration analyser
Assessment of balancing quality.
Features:
Single and two-plane balancing
Measurement of imbalance vibrations.
Power supply unit for Three Phase connection with4pole cam mains switch. Three phase indicator lamps. 25A current operated earth leakage circuitbreaker, sensitivity 30 mA.
Switch for simulation of wind or photovoltaic energy power source.
Output through 5 safety terminals:
L1, L2, L3, N and PE.
The apparatus comprises a clear acrylic mixing vessel mounted on a stainless steel base. Above this is mounted a variable speed electronic mixer with electronic torque measurement incorporated.
The rushton turbine impellor is a one piece stainless steel fabrication with eight alternate upwards and downwards pointing blades.
A set of pvc baffles can be fitted into the mixer with a simple screw mechanism to hold them in place. Under the stainless steel base is a storage compartment for the various small mixer components and the simple tools hexagonal keys required to change them. The larger mixer components are stored on pins behind the vessel.
The blades are simple to configure and position accurately in place using a single screw.
A propeller type stirrer is also included for comparison.
The flat blade impellor comes with six sizes of blade, each of which can be fitted in seven positions (vertical, plus 30/45/60 degrees leading and trailing edge).
Unit mounted on an anodized aluminum frame with painted steel panel.
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Gearbox Apparatus can be slid across each other by the use of a lever with ball knob and the whole gearbox can be rotated using the rotating handle attached on the side of the input pulley. The gears are industry standard gears finished in high quality and mesh together in different ratios within the frame. A study wall mounted frame houses all the gears, shafts, bearings and levers contained within this apparatus. All gears run on shafts fitted into bearings and the changing mechanism ensures smooth transition. A 'H' style change with gear change lever and knob allows the use of the different gears within the system.
Protractors on the input and output shaft pulleys are fitted. A set of masses and hangers is supplied to allow the shafts to be driven. The input and output pulleys allow loads to be applied for lifting and lowering. This unit is hand operated. A set of clear, transparent guards are fitted so that safety is maintained and clear visibility is ensured.
Experimental Capabilities:
Measure of the angular displacement at the input and output of the gear box and comparison with the calculated values
Enables velocity and torque ratios to be determined.
Calculation of the efficiency for different ratios according to the torque at entry
Power supply unit for variable three phase voltage suitable for supplying AC machines.
Multifunctional digital instrument that supplies voltage, current and power
Ac output: 3 x 0 ... 380 V, 8 A
Start and stop push-buttons
Motor protection circuit breaker: 6.3 to 10 A
16 A, 30 mA differential magneto-thermal main switch
Key operated emergency push-button
Modbus interface connectors.
Supply voltage: three-phase from mains.
The output voltage is set by a rotary knob with 0-100% scale.
Experiments:
The flexible design of the equipment allows the user to develop many other analysis and control exercises to suit their needs. It is good for extended or advanced control experiments, and is ideal for student project work.
Design of state re-constructors to obtain estimates of ball velocity and position
Design of analogue phase-advance compensators
Measurement of system dynamics by transient and closed-loop methods
Essential Services.
Bench space needed: 1.5 m x 750 mm
Electrical supply: 90 VAC to 250 VAC, 0.4 A, 50/60 Hz, with earth.
Unsymmetrical Cantilever Apparatus Angular adjustment can be made easily and the angular position can be read off using the integral angular scale and pointer. The free end of the cantilever has point loads applied using the load hanger and calibrated weights. Unsymmetrical Cantilever Apparatus allows the vertical and horizontal deflections of the free end of a test specimen to be measured when loading occurs along a principle axis or at a known angle. Unsymmetrical Cantilever Apparatus holds the indicators relative to the rigid end of the cantilever to ensure accurate deflection measurement. A solid base holds a rigid vertical end support for the clamping of the test cantilevers. Test cantilevers and rectangular cross section are supplied. The free end movement is measured using deflection indicators. Shear centre work can also be undertaken.
Experimental Capabilities:
Vertical and horizontal deflection of unsymmetrical cantilevers
Shear centre location
Comparison between actual and theoretical results
Moment of area
Mohrs circle
AC Power Supply Electronic Engineering Lab
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Power Supply and Electrical Protection Unit
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In practice, a small volume of concentrated solution is placed on one side of the honeycomb, whilst the other side consists initially of a large volume of pure solvent water. As diffusion of the solute occurs, the concentration within the larger volume increases, and is monitored with a conductivity sensor and meter.
Liquid Diffusion Coefficients Apparatus has developed a unique diffusion cell, which overcomes the traditional problem of slow diffusion rates in liquids requiring long observation times, but without sacrificing accuracy or introducing convective effects.
The mixture is continuously stirred with a magnetic stirrer to ensure uniform concentration within the bulk liquid. Essentially, the cell consists of a honeycomb of accurately dimensioned capillaries, positioned between two liquids of differing concentration of the solute whose diffusion coefficient is to be determined. Whilst the conductivity sensor may be readily calibrated for any required aqueous system, for introductory studies, dilute solutions of sodium chloride are recommended, for which conductivity data is provided.
The apparatus consists of a water and an air system. Each has a fluidized column and a pump. Air or water is supplied to the column via bottom porous plate and escape and the top. Fixed & Fluidized Bed Apparatus bench top apparatus is designed for a study of fluid bubbling phenomena in fixed and fluidized beds of solid particles. Control valve varies the rate of flow. Two sizes of bed materials are supplied. Measurement of flow rate is by rotameters and pressure drop is by manometers.
Experiments:
Visualization of fluidization Pressure drop through packed and fluidized beds for both water and air systems Observation of difference between particulate and aggregative fluidization Verification of Carman Kozeny equation.
The unit provides students with the opportunity of investigating the effects of a change of controller parameters (proportional band, integral and derivative times) on the control capability of the system. The Temperature Control Apparatus illustrates the control of temperature in a simulated reactor vessel by controlling the supply of coolant (air) in response to changes in process conditions. The unit is made up of typical items of control equipment currently used in industrial applications, thereby providing an excellent opportunity for familiarisation.
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The bench mounted apparatus consists of a 'shear beam', 2 supports and 3 load hangers.
The 'shear beam' of two parts, joined at a low friction joint. Internal forces created, and bending moment resisted by an underslung adjustable tension spring: an overhung spring balance provides the vertical shearing force.
Demonstration of the action of shear in a beam; measurement of shear force at a section of a loaded beam; verify equilibrium of vertical forces.
The load hangers mountable in virtually any position along the beam.
An Instruction manual for student and lecturer provided.
Set of weights.
Ball And Hoop Apparatus
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Sturdy, compact, self contained bench top unit for determining the surface strains and deflections of a flexible diaphragm under varying pressures. Round Diaphragm Apparatus the diaphragm is flexed, the strain gauge output is fed into a digital display, which is supplied. An aluminium diaphragm is clamped rigidly around its outer edge, creating a volume underneath its surface into which oil is filled. On the top surface of the diaphragm are attached 8 precision strain gauges at differing orientations.
An analogue pressure indicator monitors the pressure, whilst an electronic pressure sensor monitors the same pressure but gives an output signal to the digital display. The force applied to the diaphragm is created by pressurising the oil underneath the diaphragm using a fine adjustment control mechanism.
Experimental Capabilities:
Measurement of diaphragm disc surface strain using strain gauges
Determination of circumferential strain
Diaphragm surface profile
Measurement of diaphragm disc deflection with a dial gauge
Determination of radial strain
Comparison of actual and theoretical results
Mohr Circl
Strain gauge technology and uses.
-lab-554335448.jpg "DC Power Supply (DC 0 to 30V Variable Dc)")
DC Power Supply (DC 0 to 30V Variable Dc)
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DC Power Supply Electronic Engineering Lab
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Water circuit with tank, heater, temperature controller, pump and low water cut-off for heating and cooling (with wl 110.20 water chiller)
Supply unit for 6 different chemical reactor types
Connection of the reactors via hoses with quick-release couplings
Temperature control of the reactants and reactors
5 peristaltic pumps to deliver the reactants and products
2 combined sensors for measuring the conductivity and temperature
3 glass tanks for reactants and products.
Center of gravity of a freely suspended two-dimensional object always lies along the line drawn vertically downward from its point of suspension. A simple and economical apparatus for demonstration of geometrical center of gravity of two-dimensional objects. Each lamina has suspension holes along their periphery. The point of intersection of lines drawn from point of suspension of 2 or more holes of a lamina gives center of gravity of that 2-dimensional lamina. Comprises a clear perspex rod mounted on a base with a suspension screw at the top and four laminas of clear acrylic 1 each of circular, triangular, square and trapezoidal.
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