To the problem of cryogenic aviation-aerospace engineering

V.P.Kutakhov, M.E.Reznikov

The Air Force Technical University

3, Planetnaya street, A-190, 125190, Moscow, RUSSIA

The importance of cryogenic aeronautical space and other vehicles engineering problem depends on an increasing aviation kerosene lack.

There are practically unlimited possibilities for liquefied natural gas production and later on for liquid hydrogen use which provides aircraft performance unachievable while using oil fuel for prospective aircraft. It also gives ecological advantages and greater safety of this cryogenic fuel types. Till now the importance of this problem is not evaluated sufficiently by scientific commercial and state structures.

The specific character of Russian power resources makes us take into account liquefied natural gas as the main type of perspective aviation fuel. The reserves of natural gas in Russia in an energy equivalent ,at least exceed oil reserves on an order and make apparently 60% of world reserves and about 6% of aviation kerosene are produced from oil. Natural gas can be used to obtain cryogenic fuel completely . The cost of liquefied natural gas is 1,5-2 times less than the of aviation kerosene. The source of raw materials for obtaining hydrogen is not limited and it is cost per energy unit for the period of it is supposed wide application (in 20-25 years) will be equal to kerosene cost.

The increase of aircraft performance is provided not only by higher cryogenic fuel calorific value but also by rational use of their cooling resources the best thermodynamic properties of propulsive masses obtained from them and the function of gas cryogenic fuel even before burning.

Relying on the second law of thermodynamics the maximum possible useful work is characterized by fuel exergy but the high scale of exergy use for trust pulse creation demands the special scheme of a cryogenic power plant .Heat exchangers, an autonomous turbine and a turbodetonator can be included into in but these elements increase the power plant weight and accordingly reduce aircraft pay load. Therefore the expediency estimation of cryogenic fuel use includes, firstly, the required fuel mass share in relation to aircraft fuel as-received. With estimated version of a power plant, secondly, the change of the power plant relative weight due to the introduction (or removal) of additional devices to the engine scheme and the fuel system scheme. If the increase the power plant weight is less than the reduction of the required fuel amount at the expense of the thrust-economical engine parameters , the pay load increase will be provided.

According to the preliminary calculations the use of different cryogenic power plant schemes, allowing to use their exergetic properties to an ever greater degree can provide aircraft payload increase in several times during performing the same flight mission and accordingly it can provide to reduce fuel expenditure per a pay load unit.

The wide introduction of cryogenic fuel types to all kinds of vehicles will radically change the whole shape of fuel-power complex for the next century and will make power supply in Russia cheaper, besides it will save it is ecology.

The power-carrier change influences the social sphere, the people professional orientation and the life quality society.

The possibility to provide many thousands of working places with more favorable conditions of work is provided due to the reorientation of the considerable part of vacant coal mining industry staff for liquefied natural gas production and due to the creation and maintainance of the infrastructure for liquefied natural gas use on board the aircraft and then for its use both in regional and united all-Russia infrastructure for all kinds of transport vehicles.

In Russia the greatest advances have been achieved in the field cryogenic aviation creation. The first in the world flights of the TU-155 experimental cryogenic aircraft operating both on liquefied hydrogen and liquefied natural gas (120 sorties) have shown the real possibility of cryogenic evaluation creation . The problems supplying aircraft with cryogenic fuel have been solved and realized, including an aerodrome infrastructure as well as the measures against fire hazard and explosions during the stages from production till practical use.

The activities of leading Russian aeronautical and aerospace companies prepared conditions for the beginning of a new cryogenic phase in high effective beneficial non-polluting aviation and aerospace engineering. The formation of this engineering is closely connected with the selection of the priority type of fuel designed for it. The solution of this problem in the direction of wide cryogenic fuel use must play the same role as the transition in the middle of the 20_th century from petrol piston-engine aircraft to kerosene yet aircraft .As for psychological point of view such transition for people is similar to the transition from kerosene stoves to gaseous fuel . The cryogenic technologies will ensure hypersonic aircraft creation designed to assimilate the use of “a dead corridor “ at flight speeds about 5000-6000 km/h and even more and at the altitudes of 30-50 km and even higher.

These cryogenic aircraft researches are dual-purpose techonologies and they will allow to use cryogenic fuel in other transport vehicles, agriculture, power engineering (superconducting, removal of maximal loads in electrical systems etc.), in metallurgy, chemical industry, medicine and other branches and also the capability to export cryogenic fuel, cryogenic aircraft , cryogenic equipment and technologies.

However the problem of cryogenic fuel types for aircraft and other transport vehicles as well as for many spheres of human activity is not finally a national problem but a global problem.