The major components of a jet engine are similar across the major different types of engines, although not all engine types have all components. The major parts include:
• Cold Section:
o Air intake (Inlet) — For subsonic aircraft, the air intake to a jet engine consists essentially of an opening which is designed to min
o Compressor or Fan — The compressor is made up of stages. Each stage consists of vanes which rotate, and stators which remain stationary. As air is drawn deeper through the compressor, its heat and pressure increases. Energy is derived from the turbine (see below), passed along the shaft.
o Bypass ducts — Much of the thrust of essentially all modern jet engines comes from air from the front compressor that bypasses the combustion chamber and gas turbine section that leads directly to the nozzle or afterburner (where fitted).
• Common:
o Shaft — The shaft connects the turbine to the compressor, and runs most of the length of the engine. There may be as many as three concentric shafts, rotating at independent speeds, with as many sets of turbines and compressors. Other services, like a bleed of cool air, may also run down the shaft.
• Diffuser section: - This section is a divergent duct that utilizes Bernoulli's principle to decrease the velocity of the compressed air to allow for easier ignition. And, at the same time, continuing to increase the air pressure before it enters the combustion chamber.
• Hot section:
o Combustor or Can or Flameholders or Combustion Chamber — This is a chamber where fuel is continuously burned in the compressed air.
A blade with internal cooling as applied in the high-pressure turbine
•
o Turbine — The turbine is a series of bladed discs that act like a windmill, gaining energy from the hot gases leaving the combustor. Some of this energy is used to drive the compressor, and in some turbine engines (ie turboprop, turboshaft or turbofan engines), energy is extracted by additional turbine discs and used to drive devices such as propellers, bypass fans or helicopter rotors. One type, a free turbine, is configured such that the turbine disc driving the compressor rotates independently of the discs that power the external components. Relatively cool air, bled from the compressor, may be used to cool the turbine blades and vanes, to prevent them from melting.
o Afterburner or reheat (chiefly UK) — (mainly military) Produces extra thrust by burning extra fuel, usually inefficiently, to significantly raise Nozzle Entry Temperature at the exhaust. Owing to a larger volume flow (i.e. lower density) at exit from the afterburner, an increased nozzle flow area is required, to maintain satisfactory engine matching, when the afterburner is alight.
o Exhaust or Nozzle — Hot gases leaving the engine exhaust to atmospheric pressure via a nozzle, the objective being to produce a high velocity jet. In most cases, the nozzle is convergent and of fixed flow area.
o Supersonic nozzle — If the Nozzle Pressure Ratio (Nozzle Entry Pressure/Ambient Pressure) is very high, to maximize thrust it may be worthwhile, despite the additional weight, to fit a convergent-divergent (de Laval) nozzle. As the name suggests, initially this type of nozzle is convergent, but beyond the throat (smallest flow area), the flow area starts to increase to form the divergent portion. The expansion to atmospheric pressure and supersonic gas velocity continues downstream of the throat, whereas in a convergent nozzle the expansion beyond sonic velocity occurs externally, in the exhaust plume. The former process is more efficient than the latter.
(source:http://en.wikipedia.org/wiki/Jet_engine)
Thursday, October 22, 2009
Monday, September 21, 2009
proton saga
Second generation (2008–present)
| Second generation | |
| | |
| Also called | Proton Base Line Model (BLM) |
| Production | January 2008[4]-present |
| 4-door saloon | |
| Aichi Kikai 5-speed manual, Mitsubishi 4-speed automatic[5] | |
| 2,465 mm (97.0 in) | |
| Length | 4,257 mm (167.6 in) |
| Width | 1,680 mm (66.1 in) |
| Height | 1,502 mm (59.1 in) |
| 1,060 kg (2,337 lb)-1,085 kg (2,392 lb) | |
| Fuel capacity | 40 L (11 US gal; 9 imp gal) |
| Related | |
On January 18, 2008, Proton unveiled the successor to the 2007 Saga, which was planned to be phased out in June 2008. Retaining the Saga name, the new car is an indigenous design, designed to outperform and out engineer the Toyota Yaris compact sedan in every way. It is essentially based on a stretched Proton Savvy platform. The new model is an in-house design developed in collaboration with Korea's LG CNS and Lotus Engineering. This model enables the Malaysian company play to its strength in the home market i.e. the three-box sedan. The Proton Saga is not planned for U.S. launch but will be sold throughout Southeast Asia, in China, India and Australia
As of February 2008, approximately 23,000 customer bookings had been made for the car since its launch and the corresponding waiting time for delivery during that same period stretched up to 5 months.[6]
The Saga comes in 3 different specifications with the choice of manual or auto transmissions starting from the base specced N model to the fully kitted M model. Aichi Kikai supplies the 5-speed manual while Mitsubishi the 4-speed automatic. The basic N model retails from RM31,500 to the RM39,800 high specced M model. The new Saga would be the cheapest Proton once the RM26,999 original is retired. Proton dubs the new Saga as "The People's Car".
The new Saga is powered by the same 1.3-litre Campro engine (which was co-designed with Lotus) that is fitted to entry-level Gen-2s. Besides the 1.3L engine option, the 1.6-liter version is also available as an exclusive engine option for taxi operators[7] before being offered to regular customers.[8] Like other Proton models powered by Proton's own Campro engines, the 1.3-liter engine is rated at 94 hp (70 kW; 95 PS) at 6,000 rpm and 120 N·m (89 lb·ft) at 4,000 rpm, while the 1.6-liter version (not including the Campro CPS engine which is not being used in the Saga) produces 110 hp (82 kW; 110 PS) at 6,500 rpm and 148 N·m (109 lb·ft) at 4,000 rpm. Both engines feature the new Integrated Air-Fuel Module (IAFM) which varies the airflow into the engine to improve efficiency, smoothening out the problematic dip in the torque curve in the lower and middle rev ranges. Its output matches that of a 1.3-litre in the Satria Neo. Power delivery characteristics in both cars are remarkably different. The torque could be felt after 2,500 rpm, all the way to 4,000 rpm, where it drops off rapidly. The car feels cheap to drive and acceleration to highway speeds is good. The 5-speed manual from Aichi Kikai is not geared towards the ultimate refinement at cruising speeds, but it does offer a good spread of torque everywhere, not to mention good overtaking power anywhere from 80-120 km/h. Suspension setup consists of MacPherson struts and a stabilizer bar up front with a torsion beam in the rear. Its Lotus designed torsion beam suspension enables it to turn in sharply, hold its stance sideways through corners, understeering to a sizeable extent. Fuel economy is very good, ranging from approximately 6 L/100 km (47 mpg-imp; 39 mpg-US) for the manual transmission to 6.2 L/100 km (46 mpg-imp; 38 mpg-US) .[9] for the auto and is considerably less when traveling at 80 km/h (50 mph) in fifth. Top speed is around 160 km/h (99 mph) (the owners manual doesn't recommed exceeding 120kmh) and 0-100 km/h time is about 16 seconds. The electrical system has also been updated with coil-on-plugs instead of the traditional ignition cable system, eliminating power loss.
It has boot space of (413 l (14.6 cu ft)).[5] Because the new Saga, like its predecessor, is expected to be standard among Malaysian taxicab operators,[7] the car is designed to accommodate a compressed natural gas tank without considerably restricting boot space. There is ample room for 5 adults and the interior is bigger than the old Saga. Top-of-the-line version have a set of 14-inch tyres and ventilated disk brakes for added traction, providing the car with strong braking force and better road holding. Only one airbag for the driver is also fitted to the medium-specced models onward.
Since the official launch of the second generation Proton Saga in January 2008, the car has won 3 major automobile awards. Autocar Asean, the Malaysian edition of the longest running car magazine in history has awarded the new Saga "Winner of the Small Sedan/ Hatchback Category" for 2008. Shortly after that, the car was voted as the "Best People's Car" at the Asian Auto - VCA Auto Industry Award 2008.[10] In November the same year, the new Saga won yet another major Malaysian automobile accolade when it was declared the "Winner of the Entry Level Car Category" under the New Straits Times/ Maybank Car of the Year Awards for 2008.[11]
Thursday, September 17, 2009
computer software
Software refers to parts of the computer which do not have a material form, such as programs, data, protocols, etc. When software is stored in hardware that cannot easily be modified (such as BIOS ROM in an IBM PC compatible), it is sometimes called "firmware" to indicate that it falls into an uncertain area somewhere between hardware and software.
http://en.wikipedia.org/wiki/Computer#Notes
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