No other transportation system could achieve within a century such a huge step forward as the aviation industry. Progress in terms of technological possibilities, the safety, environmental friendliness and the number of aircraft movements and passenger kilometers. From a technological perspective, the engine to the essential core of aviation.
The most influential of all the technological advances in aviation have been made in Germany just before and during the Second World War. The completely demilitarized after the First World War, disenfranchised and tortured people was only after the termination of the Versailles Diktat bloom again, causing a veritable wave of modernization in all areas. "Not the mother of invention" The principle was the new phase of enlightenment flooded with new inventions with the renaissance hotel tradition, was not neglected. In similar style as the outlet of the 20th against globalization Century, computer technology has promoted, developed in aviation due to the enormous needs of rearmament Third Reich. However, even gave the sensational discovery of Turbojettriebwerks not the German victory. Through the "patent theft" in the mid 40's years, all building plans came German Waffen and aircraft systems in Allied hands, these replicas in any version. Thus the similarity of the aviation industries on both sides of the Iron Curtain plausible, just that the "Comet" (the first jet-powered passenger aircraft of Boeing in 1950) virtually identical replica of German Jumo-004 engines possessed. The increasing traffic density and the associated environmental impacts, together with the oil crisis forced the aviation industry to new innovations, which led ultimately to the fact that we are now pushed by turbofan engine through the world. 
In a classical turbo-jet engine, the ambient air from the compressor (rotors in the front) is drawn in and compacted. A higher number of compression stages (rotors shifts in a row) guarantees generally have a higher compression pressure. The first engines had 8 stages, reaching a positive pressure in relation to External pressure of 3.1: 1, a Boeing passenger plane engine has 17 steps and compresses the air in the ratio 12.5: 1, the new Airbus A380 has 14 steps and reaches a density of 44: 1 In the middle of the engine is the combustion chamber where the compressed air is mixed with fuel and ignited. This results in modern engines, an operating temperature of up to 1,800 K (1,527 ° C =), so a further pressure is generated. This pressure is used before the ejection process in order to drive the turbine, which drives the compressor via a shaft forward. When this cycle under way, the compressed gas is expelled through the exhaust nozzle. At the exit point from the nozzle relaxed, the pressure is on the ambient pressure, so that the gas expands and accelerates in the ejection direction. By thermodynamic basis of the experiment's Rüchardt the pressure can be calculated with the first compressed and heated gas is then ejected back. Do we have the operating system, the formula: {(T_inside / T_outside) ^ k = (p_inside / p_outside) ^ (k-1))} (k = 1.4). This allows compression temperature and pressure increase calculated by the combustion. Be neglected while the systemic heat loss and possible gas-dynamic changes. Calculated If the heat of compression: Druckadiabat charge; {(300'000Pa / 100'000Pa) ^ 0.4 = 1.55}, T-ratio (assuming that outside temperature is 27 ° C, which is 300K); {(T_inside/300K ) ^ 1.4 = 1.55}. conversion; {1.55 ^ (1/1.4) = 1.3675}. insertion; {1.3675 * 300 = 410K = T_inside }. On the assumption that the starting temperature in the combustion chamber at Jumo-004 engines 1'050K, the resulting pressure can be calculated after ignition (gas temperature is always lower than combustion chamber temperature of 1,650 K, because the gas does not absorb the gant enthalpy): 1 3.73 ^ {(: T_ratio adiabatically: {(1'050K / 410K) ^ 1.4 = 3.73} , inversion formula p / 0.4) = 9.26} , based on the compressor pressure: {300'000Pa * 9.26 = 8'063'800 Pa } , which is more than 80 - fold the atmospheric pressure.
After deduction can reduce the pressure in the turbine the exit velocity calculated by the following formula: { V_OUT = sqrt (2 * delta_p / rho)} [sqrt = "root"]. With a Junkers Jumo 004 jet engine with an efficiency of around 12% can therefore estimate that the pressure difference between turbine and outside air is about 1'000'000Pa used this value in the formula and a rho value of 1.3, this gives an ejection speed of 1,240 m / s. The A380, it is 1,850 m / s, which is almost the value of a rocket - borders (2 4.5 km / s).
If you want to exit from the calculated speed, the thrust of an engine charge, one needs the Flow [Iv] { V_OUT *} A_düse (A = area in m ^ 3) and the Flüchtgkeitsfaktor [f] {f = (delta_p / Iv ^ 2)} . The performance can now by the product of {f * Iv ^ 3} derive . As an example, calculate the starting performance of the above graduated Arado 234B twin-engine (thrust nozzle exit faces total 0.002 m ^ 2, jet print 10 x atmospheric pressure): = {delta_p 1'100'000Pa-100'000Pa 1'000'000Pa =} = sqrt {V_OUT } (2 * 1,000,000 / 1.3) = 1,240 m / s} {1'240m / s * 0.002m ^ 2 = 2.5m ^ 3 / s = Iv, {1'000'000Pa / ( 2.5 ^ 2) = 160,000 = f}, {160,000 * (2.5 ^ 3) = 2,500,000 watts }. (Comparative A380: 66'000'000 W).
If we estimate the shear force, you take this power and then divide by the exceedingly high speed 240 m / s; 2,500,000 {W / 240 m / s = 10,400 N }. This estimate is the one declared on wikipedia.com 9,800 N thrust force per Jumo-004 engine close relative if one considers that occur in reality, the operations are not 1-1 after the theoretical model, such as the gas does not desquamated clean air, but a gas mixture, which is dynamically different gas behaves slightly differently than air, would also clean up various rounding differences.
turbofan engine:
In contrast to the works of the turbofan Turbojettriebwerk an essential part of the fan. It is not the whole aspirated air through the compressor and combustor sent, but some is passed around in the casing to the drive core, which gives a recoil principle as a prop . This technological device requires an additional drive shaft, and is therefore something mechanical anfwändiger, But they paid out more than once. Apart from the amazing energy efficiency (up to 40% efficiency, which is for an internal combustion engine is very high), it reduces noise and vibration can resolve many problems in the transmission. In recent decades, only produced turbofan engine. advantages of the "bypass air" - Technology:
as "bypass air" is referred to the flow of air from the fan slightly compressed outside the shell around the core is sent. Increasingly, in the engine technology of the proportional share of increased air bypass, as it they can use with increasing efficiency of the engine more efficient.
The trick to reduce this technology aircraft noise is that the cold-paid "bypass flow" is behind the nozzle with the hot combustion stream mixing and friction noise between the hot and cold air causes the most part within the engine shell . The sound can be retained by a kind of shock.
What in this system contributes to energy saving, is the prevention of movements of rotors in supersonic speed, as occur when breaking the sound walls, gas-dynamic losses.
example, the turbine and compressor of an introduced above Junkers Jumo-004 engine, 9,000 revolutions per minute, equivalent to 150 U. / s appropriate and that an angular velocity of 942 rad / s. Because these turbines and compressors have a radius of about 30cm, can be combined with 0.3 * 942 = 283 m / s, 1,017 km / h, calculate the velocity at the outer edge of the circle. Speed of sound is about 343m from / s, so as far more problematic. However, when the flying object goes out and wants to look at the absolute top speed of the rotors, you must use the following formula: { v_absolut = sqrt (v_plane ^ 2 + (w * r) ^ 2)} (w = Winkelgeschwindgkeit). Substituting the numbers, you will find that one at a speed of 190m / s, which is 684 km / h comes to the sound barrier, which thus explains why he exceed 700km / h only with considerable effort and also to 11,000 m its max. Cruising speed of 870 km / h was able to maintain long-term.
nice to know: The speed of sound can be [c] by the formula {c = sqrt (k * R * T)} calculated (R = 287), so it is much more dependent on temperature than on the air composition. Speed of sound is thus to 11,000 m above sea level. only at 297 m / s.
For larger engines, eg for Passenger aircraft, would have such a compressor has a radius of 0.5m, resulting in an angular velocity of 942 rad / s outside of a speed of 417m / s, which is 1'696 km / h, which is significantly higher in the supersonic range. This would cause movement-related energy losses, although the machine itself is not even moving. Precisely for this reason, the turbofan, the ingenious solution to work with a transmission of two waves: an inner, rapidly rotating shaft, which drives the compressor and provides for the combustion. In the opposite direction, the shaft rotates slowly with the large radius, so the blower is operated. The two counter-rotating shafts resemble their angular momentum to each other out, so a big vibration problem is solved.
basic distinction between "high-bypass" and "low-bypass - construction. The latter is the name for turbofan engine, where more air through the combustion going around the outside as, in modern high-bypass engines leads to over 80% of the incoming air mass through the jacket around the core. The proportional distribution of air in the different channels is variable, once the acceleration phase of the machine is finished running the engine power of about 30% of their capacity, so the engine needs less air in the combustion chamber.
afterburner
normal aircraft engines usually allow any flights at supersonic speeds. Once Mach 1 is reached approximate forms in front of the moving body with a disproportionately increased air resistance. One speaks of a "sound barrier", which makes it difficult for energy technology to break through them. If you want to do this but you need a so-called afterburner. This is a kind of further combustion chamber outside the flying object. Due to the great heat in the engine more air is sucked in, as would be necessary for ideal combustion. The exhaust of an aircraft is thus oxygen. This oxygenation is utilized with the afterburner, and generates a further boost. The picture of these two Mirages, the flame of burning residual oxygen is clearly visible. Besides the fact that he works with air, the afterburner effect on a similar principle as a rocket engine, ie the emission rate is within the Earth's atmosphere at about 4,500 m / s.. The reason why only a few suitable for military supersonic aircraft fly faster than 2,000 kilometers per hour, often lack the technological limitations, but the hot wall. One goes beyond this, If the material is stressed because of the enormous heat, which arises from the friction with the air. From an efficiency of energy use her but it is nonsense to exceed Mach 1 just as the use of an afterburner around the 10 - times the normal consumption of fuel as an engine. As versatile as the aviation technology may be, it is always to balance the purposes for which what is most reasonable.
images / sources:
Images:
of-werftverein.de
altavista.com pictures /
luftarchiv.de
technical data:
sfa.de
aboutfacts.net
Royal Air Force Museum London
formula / basis:
f lectures System Physics . aviation, ZHAW
script, Aeronautical Science, QMU
