PRESENTATIONON

SCRAMJET ENGINEByShashwat MishraBTech-Mechanical Eng.(VIth Sem)201410102110068

What is A Scramjet Engine?

A scramjet (supersonic combustion ramjet) engine is variant of a ramjet engine in which engine carries hydrogen (as a fuel) and takes oxygen ( as oxidiser ) from atmospheric air.

As in conventional rocket system they carries the oxidiser along with them.

Apart from rockets and missiles , the engine can find its application in planes for the purpose of commercial travel by considerably reducing the travel time.

WHY A NEED FOR A SCRAMJET ENGINE

Nearly 70 % of the propellant ( fuel – oxidiser combination ) carried by today’s launch vechicle consists of oxidiser.

To reduce the cost and for increasing the high speed of mach 6

next generation launch vehicle must use a propulsion system which can utilise the atmospheric oxygen during their flight through the atmosphere.

COMPONENTS OF SCRAMJET ENGINE

The scramjet is composed of three basic components :

1) A Converging Inlet, where incoming air is compressed and decelerated.

2) A Combustor, where gaseous fuel is burned with atmospheric oxygen to produce heat.

3) A Diverging Nozzle, where the heated air is accelerated to produce thrust.

• In scramjets, the engine inlet is designed so it doesn’t create as much compression as in ramjet, allowing the air to zip through the engine at supersonic speeds.

• The simplest type of air breathing engine is the scramjet engine and simplified sketch of engine is given in figure.

PRINCIPLE OF WORKING

Scramjets works on the same principle of ramjet.

Based on air breathing propulsion system.

The engine caries hydrogen as a fuel & takes oxygen from the atmospheric air.

Basically in order to achieve the initial speed, a second engine is integrated in the Scramjet model, it may be rocket or turbojet engine.

PRINCIPLE OF WORKING cont.

Hot air flows in the combustion chamber and at this moment the propellant i.e. hydrogen (having a very low ignition temperature) are injected by the injector in the combustor, where it gets self ignited within a millisecond and the combustion process is carried out at supersonic speed.

The fresh air supply to the diffuser builds up a pressure at the diffuser so that these burned gases cannot expand towards the diffuser. Instead the gases are made expand in combustor towards tail engine hence providing the required thrust.

ADVANTAGES

Does not have to carry oxygen. No rotating parts, makes it easier to manufacture. Less weight and simple design. As the hydrogen is used as a propellant

combustion is carried out at supersonic velocity with the help of oxygen from the atmosphere. As a result of that, steam is being exhaust gas which is eco-friendly in nature.

DISADVANTAGES

A scramjet cannot produce efficient thrust unless boosted to high speed, around Mach 5.

As a result an additional propulsion systems are required.

Lack of stealth.

Testing difficulties.

RECENT DEVELOPMENTS

Hyper-X “Scramjet” A new program, called Hyper-X, was launched by NASA in 1997. The goal is to build working jet airplanes that use a clever combination of ramjet, scramjet, and rocket engines to reach sufficient speeds to achieve orbit around the earth. These planes would be conventional rocket engines to get started and then switch over to ramjet power at Mach 2 or 3, and then scramjet power at about Mach 5.

SCOPE IN INDIA

Only few country like USA , RUSSIA , INDIA and CHINA have succeeded at developing sramjet technologies.

In year , 2010 , ISRO testfired its Advance Technology Vehicle

( ATV-DO1 ) with a scramjet engine combustor module . It was a suborbital ballastic trajectory based experiment but it was failed due to some technical failure.

FAILURE

SUCCESSFULLY FIRED On August 28 , 2016 , ISRO successfully tested its

scramjet engine on second developmental flight of its Advanced Technology Vehicle ATV – D02 .

Also HSTDV has been ground - tested at hypersonic speeds for 20 seconds.