TURBOJET ENGINES

Introduction

Turbojet engine takes its oxygen supply from the surrounding atmosphere. The turbojet engine consist of a diffuser, compressor, combustion chamber, turbine and a expansion nozzle.

The air is compressed in to the chamber, heated and expanded by the fuel combustion and then allowed to expand out through the turbine in to nozzle were it is accelerated to high speed to provide propulsion (moving forward)

Working Principle: - Atmospheric air enters into the diffuser with the same velocity as that of the propulsive unit. The function of the diffuser is to convert the kinetic energy of entering air in to pressure energy of it. High pressure air now enters into the compressor were its pressure is further increased and its temperature also increases correspondingly.

The high pressure and high temperature compressed air now inters in to a combustion chamber in which a liquid fuel is injected through a ring of injectors by means of a pump. In the combustion chamber, the fuel burns at constant pressure by coming in contact with hot compressed air. Hot gases thus produced in the combustion chamber, now enter into a gas turbine in which it expands producing power. It is with this power that compressor and the fuel pump are operated. The exhaust gases from the turbine now pass in to the atmosphere through the expansion nozzle. As the exhaust gases pass through the nozzle. Its pressure energy is converted into kinetic energy and the gases leave the nozzle with a very high velocity producing a reactive force or thrust in the opposite direction. This thrust carries the propulsive unit forward. To start the unit, a starting device such as electric motor is required.

The Turbojet Engines Are Used In Aircraft

Advantages of turbojet engine

The following are the advantages

· Simplicity in construction

· Free from vibrations

· Higher rates of climb

· Uninterrupted and smooth power supply

· Low specific weight (weight to power ratio)

· Speed as high as 3000 kmph are possible

· Minimum over-hauling

Disadvantages of turbojet engine

The following are the disadvantages

· Low efficiency

· expensive materials

· not efficient in performance below 550 kmph speed

· More noisy

Comments

RATCHET & PAWL MECHANISM

INTRODUCTION · This type of mechanism is used in producing intermittent rotary motion from an oscillating or reciprocating motion member. · The ratchet and pawl mechanism consists of a ratchet wheel and a pawl, as shown in figure. · The ratchet consists of a round gear or linear rack with teeth. · A pawl is a spring loaded member that engages the teeth of the ratchet the teeth of ratchet is uniform. Theory of operation A ratchet consists of a round gear or linear rack with teeth. A pawl is a spring-loaded member that engages the teeth of the ratchet. The teeth are uniform, with each tooth having a moderate slope on one edge and a much steeper slope on the other edge. When the teeth are moving in the unrestricted (i.e., forward) direction , the pawl easily slides up and over the gently sloped edges of the teeth, with a spring forcing on it into the depression between the teeth as it passes the tip of each tooth. When the t

Battery ignition system

Most of SI engine used battery ignition system. In this system a 6 volt or 12 volt battery used to produce spark. Passenger cars, light truck, motorcycles and large stationary engines are fitted with this system. Main Parts of battery ignition system: Battery A battery is used to provide energy for ignition. It is work as storage of energy and charged by dynamo, which is driven by engine. It converts chemical energy to electric energy. Ignition switch It is used to turn on and off the ignition system. Battery is connected to the primary winding of ignition coil by ignition switch and ballast resistor. Ballast resistor It is connected in series with primary winding to regulate current in primary winding. It is used to prevent injury due to overheating of ignition coil. It controls the current passes through primary winding. It is made by iron. Iron has property of increase electrical resistance rapidly by increase in tempera

Block diagram energy conversion in hydropower plant

Explain with the help of block diagram energy conversion in hydropower plant? A power generating station which uses the kinetic or potential energy of water for generation of an electrical energy is called hydroelectric power plant. Potential energy : when water is stored at high level it has potential energy. The potential energy is function of difference of water level between two points The difference in level of water between two points is called water head. Kinetic energy: water ,when it is in motion is known is kinetic energy. Theory of operation The water comes from the dam or reservoir through the penstock is directed on the blades of turbine runner , creating a force on the blades .since the runner is spinning ,the force acts through a distance ,in this way energy is transferred from the water flow to the turbine . The turbine is coupled with generator hence

MECHANICAL ROCKS

Search This Blog