Author: Haroon Khalil

A Prony brake (Figure 18.13) develops mechanical friction on the periphery of a rotating pulley by means of brake blocks that are squeezed against the wheel by tightening the bolts until the friction torque F · R balances the torque W · L.   Torque, T = F × R = W × L Figure 18.13 Prony Brake Dynamometer

A torque is a vector product of force and radial distance that measures the tendency of a force to rotate an object about an axis or centre. A dynamometer is a device for measuring mechanical force, or power, transmitted by a rotating shaft. Since power is the product of torque and angular speed, all power-measuring…

Cantilever beam can be used for measurement up to 10 kg of weight. One end of the cantilever is fixed, while the other end is free; load is applied at this end, as shown in Figure 18.12. Figure 18.12 Cantilever Beam The strain developed at the fixed end is given by the expression: where l = Length of the…

Load Cell: Force can be measured easily from a load cell. Weigh bridge is one of the most common applications of load cell. Here two strain gauges are fixed so as to measure the longitudinal strain, while two other measuring the transverse strain, as shown in Figure 18.11. The strain gauges, measuring the similar strain (say, tensile) are…

There are several methods of measuring strain; the most common is a strain gauge, a device whose electrical resistance varies in proportion to the amount of strain produced in the device. For example, the piezoresistive strain gauge is a semiconductor device whose resistance varies non-linearly with strain produced. The most widely used gauge is the…

The proper design of load carrying components such as shafts, pressure vessels, and support structures for machines requires information about the distribution of forces within the particular component. The experimental analysis of stress is accomplished by measuring the deformation of a part under load and inferring the existing state of stress from the measured deflections.…

The orificemeter and similar devices such as venturimeter and flow nozzle work on the principle of constant area variable pressure drop. Here the area of obstruction is constant, and the pressure drop changes with flow rate. On the other hand, rotameter works as a constant pressure drop variable area meter. It can only be used…

In orificemeter, an orifice plate is placed in the pipe line, as shown in Figure 18.7. If d1 and d2 are the diameters of the pipe line and the orifice opening, then the flow rate can be obtained as: Figure 18.7 Orificemeter Volume of flow, where Cd is known as coefficient of discharge; its value ranges from 0.6 to 0.7.

Hydrodynamically, there are two types of fluid flow: laminar and turbulent. Whether a flow is viscous or turbulent can be decided by the Reynold’s number RD. If RD > 2,000, the flow is turbulent otherwise laminar. In the present case we will assume that the flow is turbulent, that is the normal case for practical situations. Let us…

Flow measurement is the quantification of volume of fluid movement. Flow can be measured in a number of ways. Positive-displacement flowmeters accumulate a fixed volume of fluid and then count the number of times the volume is filled to measure flow. Other flow measurement methods rely on forces produced by the flowing stream as it…