Turbo Engine

When we think about super cars and supersonic aircrafts, a question always comes in mind that how could these cars attains such a high speed, and the answer is just by using a turbo charged engine.

A turbo-compound engine is a reciprocating engine that employs a blowdown turbine to recover energy from the exhaust gases. The turbine is usually mechanically connected to the crankshaft, as on the DC-7B and the Super Constellation, but electric and hydraulic systems have been investigated as well. The turbine increases the output of the engine without increasing its fuel consumption, thus reducing the specific fuel consumption. The turbine is referred to as a "blowdown turbine" , as it recovers the energy developed in the exhaust manifold during blowdown, that is the first period of the exhaust process when the piston still is on its expansion stroke, this is possible since the exhaust valves open before bottom dead center.

Turbo-compounding was used on on several airplane engines after World War II, including the Napier Nomad and the Wright R-3350. The first aircraft engine to be tested with a power-recovery turbine was the Rolls-Royce Crecy, during WWII.

Turboprop Engines

Turboprop engines are gas turbine engines which is used in aircraft. The gas turbine is designed in such a manner that it drives aircraft propeller using a reduction gear. Turboprops have their origin in the first half of the 20th century.  Gvorgy Jendrassik is considered to be the father of the turboprop, with his first small scale design for the engine appearing in 1937.

The United Kingdom was the site of the production and sale of the earliest mass marketed turbo prop engines. The Rolls Royce Company developed and marketed the RB.50 Trent, considered by many to have set the standard for later developments in turboprop technology. Rolls Royce made use of the knowledge acquired during the development of the Trent and later produced a highly reliable turboprop engine known as the Dart. The design and function of the Dart was such that production of the engine continued for over fifty years.

Turboprop engines are generally used on small subsonic aircraft, but some aircraft outfitted with turboprops have cruising speeds in excess of 500 knots (926 km/h). Large military and civil aircraft, such as the Lockheed L-188 Electra and the Tupolev Tu-95, have also used turboprop power. The Airbus A400M is powered by four Europrop TP400 engines, which are the third most powerful turboprop engines ever produced, after the Kuznetsov NK-12 and Progress D-27.

The turboprop engine is a simple device that includes a turbine, intake, combustor, compressor, and a propelling nozzle. Air flow is processed by the intake and then passed to the compressor. Fuel is added to the compressed air as it passes into the combustor, creating the energy as the mixture passes into the turbine. It is within the turbine that the power used to drive both the propellers and the engine proper is created. A portion of the power keeps the compressor functioning and continuing to pass air into the combustor. The remainder is passed through the propelling nozzle and helps to create the thrust generated by the propeller.

Turboprops are very efficient at flight speeds below 390 knots (725km/h) because the jet velocity of the propeller and exhaust is relatively low. Due to the high price of turboprop engines, they are mostly used where high-performance short-takeoff and landing capability and efficiency at modest flight speeds are required.

Abrasive Jet Machining

Abrasive Jet machining is an unconventional machining process, unconventional means there is no physical contact between tools and the workpiece.

Principle

Principle behind the abrasive jet machining is very simple, a stream of jet is used for machining. Jet of air or water mixed with fine abrasive materials strikes the workpiece and in this way machining is done.

Construction

Abrasive jet machine have components as listed below:

• Gas cylinder,
• Filter,
• Pressure regulator,
• Abrasive chamber,
• Vibrator,
• Handle,
• Nozzle.

 Working

Gas cylinders contains gas which is carried out by pipes, passing away from filter, which separates the dust particles and the pressure regulator is used to maintain the required gas pressure, then the gas collects in chamber where fine abrasive particles (50micron) are present. Here gas mixes with abrasive and a vibrator is connected to the chamber for better mixing which vibrates at 50c/s. Then this mixture is carried to the nozzle which concentrates the mixture at the workpiece and erodes the material from the workpiece.

Material removal rate of abrasive jet machining is quite high as compared to conventional machining.

Hydraulic Brakes

Hydraulic brake is a braking arrangement which uses brake fluid, to transfer power from controlling mechanism to the braking mechanism.

Construction

The most common arrangement of hydraulic brakes for passenger vehicles, motorcycles, and scooters,  consists of the following:

• Brake pedal or lever,
• A push rod or actuating rod,
• A master cylinder assembly, containing a piston assembly made up of either one or two pistons, a return spring, a series of gaskets / O-rings and a fluid reservoir,
• Reinforced hydraulic lines,
• Brake caliper assembly usually consisting of one or two hollow aluminum or chrome-plated steel pistons called caliper pistons, a set of thermally conductive brake pads and a rotor also called a brake disc or drum attached to an axle.

The system is usually filled with a ethylene-glycol based brake fluid other fluids are also be used.

Working 

In hydraulic braking system there are two cylinders and a disk brake, the cylinders are connected by tubes with piston inside the cylinder. The cylinders and tubes are filled with incompressible oil. The two cylinders have the same volume, but different diameters, and thus different cross-section areas. The one with the smallest diameter is called the master cylinder. The spinning disc brake will be placed down at the piston with the larger cross-section. Suppose the diameter of the master cylinder is half the diameter of the other cylinder, then the master cylinder has a cross-section four times smaller. Now, if the piston in the master cylinder is pushed down by 80 mm, with 10 newtons (N) of force, the slave piston will then move 20 mm, with a force of 40 N.
This force can be further increased by inserting a lever connected between the master piston, a pedal, and a pivot point.
Thus a hydraulic system provides a large braking force to stop a vehicle.

Supercharger

Supercharger is an air compressor generally used in super cars to increase pressure, temperature, and density of air supplied to an internal combustion engine. The compressed air supplies a greater amount of oxygen to engine for better combustion than the natural aspiration of engine, which makes it possible for more fuel to be burned and more power is produced by the engine.

Power for the supercharger is provided mechanically by belt, chain, or gear connected to engine's crankshaft. When power is provided by turbine powered by exhaust gas then it is called turbo-supercharger.

There are mainly two types of superchargers:

Positive displacement: Positive displacement pumps delivers a fixed volume of air per revolution at all speeds.

Major types of positive displacement pumps include:

• Roots,
• Lysholm twin-screw,
• Sliding vane,
• Scroll type supercharger also called G Lader.

Dynamic compressor: Dynamic compressors works on accelerating the air to high speed and then exchanging that velocity for pressure by diffusing or slowing it down.

Major types of dynamic compressor are:

• Centrifugal,
• Multistage axial-flow,
• Pressure wave supercharger,

Regenerative heat exchanger

A regenerative heat exchanger or a regenerator is a heat exchanger where heat from hot fluid is first passed to a storage medium and then it is passed to the cold fluid which absorbs the heat. In regenerative heat exchanger, the fluid on either side of heat exchanger can be the same fluid.

Regenerative heat exchanger was one of the most important technologies developed during industrial revolution. It is used for hot blast in blast furnace.

Also used in steel industries, glass industries, in high pressure boilers and in many chemical industries.

The first regenerator was developed by Dr. Robert Stirling in 1816 and was used as a component of his stirling engine.

Toughness

Toughness is the ability of a material to absorb energy and plastically deform without fracturing. It is also defined as the resistance to fracture of a material when stressed.

Mathematical definition

Toughness can be determined by measuring the area underneath the stress-strain curve and its energy of mechanical deformation per unit volume prior to fracture. 

Unit Of  Toughness 

Toughness is measured in units of joules per cubic metre (J/m³) in the SI system and inch-pound-force per cubic inch (in·lbf/in³) in US customary units.