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FIND OUT MORE. Electromagnetism 186 • Energy 166 • Human Impact 64 • Machines 196–197 • Rockets 28 • Transport 200–201

Science and Technology^199

4 CAR ENGINE
In this high-performance, six-
cylinder car engine, the power
strokes from the pistons take
place in sequence. The power is
transferred smoothly through
the crankshaft to the gearbox
and wheels.

EXHAUST STROKE

The exhaust valve opens. The

exhaust gases (waste gases) are

forced out of the cylinder as

the piston rises.

POWER STROKE
The hot gases expand, which
forces the piston down,
transferring power to the
crankshaft.

Exhaust

valve

Hot gases

expand and

force the

piston down

Crankshaft

rotates

c. 60 CE Steam powers

an engine

1698 First practical

steam engine

1765– James Watt

1790 improves steam

engines

1804 First steam

locomotive

1876 First internal

combustion

engine

1903 First gas

turbine

1937 First jet engine

ENGINE DEVELOPMENT

HOW CAN ENGINE EFFICIENCY BE IMPROVED?

The more fuel a car needs to work, the less engine

efficient it is. Scientists are developing cars that use

less fuel, and therefore do not waste energy or pollute

the air. They are also making cars that use

different sources of energy, such as

solar panels, electric motors, or

hydrogen fuel, which is

pollution-free.

WHAT ARE THE DIFFERENT TYPES OF TURBINE?

Water-mills and windmills are examples of water and

air turbines. They are not heat engines because they

do not rely on heat to produce motion. Gas and steam

turbines are powerful heat engines – the turbine

blades are spun by hot gases from burning fuel, or by

high-pressure steam from a boiler. They are used to

drive large ships and turn power station generators.

WHAT MAKES A TURBINE TURN?

The flowing gas or liquid pushes the turbine blades,

spinning the shaft. The turbine is connected to a

generator. In a modern turbine, the angled blades

have a similar shape to aircraft wings to maximize

the force generated. The fluid may pass through two,

three, or more sets of blades arranged in sequence –

to convert as much energy as possible to motion.

A vehicle’s fuel consumption is measured by how much fuel it

uses to travel a certain distance. The fuel consumption of a car

depends on its engine power, its weight, its aerodynamics (how

smoothly it moves through the air), its speed, and how it is driven.

HOW DOES A JET ENGINE WORK?

Air entering the front of the engine is compressed

by rotating blades and fed to a combustion chamber.

Jet fuel injected into the chamber mixes with the

compressed air, and burns at a high temperature. This

makes a jet of gas shoot from the rear of the engine

at such speed that it thrusts the aircraft forwards.

A turbine is an engine that has a set of

blades or paddles, rotated by a moving

liquid or gas. Turbines are used in

hydroelectric power stations and ships.

1 STEAM TURBINE

This turbine rotor is spun by

high-pressure steam. It turns a

generator to produce electricity

at a power station. The rotor

blades are arranged in stages.

Multi-stage turbines are the most

efficient as they take all the

energy produced by the steam.

FUEL CONSUMPTION

TURBINES

2 ELECTRIC CAR

Solar panels in this car’s roof feed

power to its batteries. Electric

cars do not pollute city streets

with exhaust fumes.

Belt

drives the

alternator

to charge

the battery

FRANK WHITTLE

English, 1907-1996

Engineer Frank Whittle

proposed the idea for jet

aircraft in 1928. But it was

not until 1937 that he built

the first successful engine.

His ideas were developed in

World War II, and the first

Whittle engine jet fighters

flew in 1944.

engines