JSS2 Basic Technology Lesson Note on Air Flow; Pneumatic and Hydraulic Devices

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TOPIC: AIR FLOW, PNEUMATIC AND HYDRAULIC DEVICES.

CONTENT

Air flow
Bernoulli’s principle
Aerodynamics
Definition of hydraulic and pneumatic devices.
Examples of Hydraulic and Pneumatic devices.
Components of the machines
Working principle/operation of hydraulic and pneumatic device
Uses of Hydraulic Devices
Uses of Pneumatic Devices
Advantages of Pneumatics Devices
Advantages of hydraulic Devices

SUB-TOPIC ONE (1)

Air flow
Bernoulli’s principle
Aerodynamics

(a) Air flow

This refers to air molecules in motion. Flow is an exclusive property of all fluids (liquids and gases). However unlike liquids, air does not necessarily need a channel or container for it to flow. Breeze/wind is formed when molecules of air are set in motion. Molecules of air can be set in motion by any of the following processes:

Blowing air
Using the bellows (often used by blacksmith)
Using pumps
Using fan

When liquids flow through channels, agents such as gravity or a mechanical device is necessary to sustain the flow. Liquid (water) flow could either be laminar (streamline) or turbulent.

In laminar flow, all the portions of the water move gently in a path parallel to the confining channel.

Turbulent flow is a force flow; water particles do not move in a straight line. An example of this is the water flow in drainage during a heavy downpour.

Moving air molecules possess energy. This energy can be applied in the following processes;