Pulse detonation engine

Pulse detonation engine

The pulse detonation engine (PDE) marks a new approach towards non-continuous combustion in jet engines. They are light, easy to manufacture, and promises higher fuel efficiency compared even to turbofan engines. With the aid of latest design techniques and high pulse frequencies, the drawbacks of the early designs promise to be overcome. To date, no practical PDE engine has been put into production, but several test bed engines have been built by Pratt & Whitney and General Electric that have proven the basic concept. Extensive research work is also carried out in different NASA centers. In theory, the design can produce an engine with the efficiency far surpassing gas turbine with almost no moving parts. These systems should be put to use in the near future.

All regular jet engines operate on the deflagration of fuel, that is, the rapid but relatively gentle subsonic combustion of fuel. The pulse detonation engine is a concept currently in active development to create a jet engine that operates on the supersonic detonation of fuel.

Pulse detonation engines (PDEs) are an extension of pulse-jet engines. They share many similarities including the operating Humphrey’s cycle. However, there is one important difference between them, namely, PDEs detonate, rather than deflagrate, their fuel. Detonation of fuel is a sudden and violent supersonic combustion of fuel that results in immense pressure which in turn used as thrust.

Combustion process in PDE resembles perfectly constant volume combustion, while combustion process in valveless and valved pulsejets is approximated only as a constant volume process. Others identify combustion in PDE as neither constant volume nor constant pressure. Details of test results of both PDE and pulsejet are given in. PDE achieves higher specific impulse in comparison with pulsejet engines for same operating static conditions. The main objective of PDE is to provide an efficient engine that is primarily used for high-speed (about Mach 5) civilian transport as well as many military applications including supersonic vehicles, cruise missiles, UAVs, SSTO launchers, and rockets. However, their noise and the drop in efficiency at higher Mach number imply that pure PDEs will likely not to be used often for large-scale applications.

The single flight of an aircraft powered by a pulse detonation engine took place at the Mojave Air & Space Port on 31 January 2008. The aircraft selected for the flight was a heavily modified Scaled Composites Long-EZ, named Borealis.

The engine consisted of four tubes producing pulse detonations at a frequency of 80 Hz, creating up to 890 Newton of thrust and using a refined octane as fuel. A small rocket system was used to facilitate the liftoff of the Long-EZ, but the PDE operated under its own power for 10 s at an altitude of approximately 100 ft (30 m). This demonstration showed that a PDE can be integrated into an aircraft frame without experiencing structural problems from the 195 to 200 dB detonation waves. Pulse detonation engines use intermittent detonation waves to generate thrust.

Unlike the pulsejet, combustion in PDE is supersonic, effectively an explosion instead of burning, and the shock wave of the combustion front inside the fuel serves the purpose of shutters of valved pulsejet.

I. Answer the questions:

What are the advantages of the PDE?
What do all regular jet engines operate on?
What is the main difference between PDEs and pulse-jet engines?
What is the main objective of PDE?
What is the combustion in PDE unlike the pulse-jet?

II. Find the English equivalents:

непрерывное сгорание
новейшие конструкторские технологии
высокая эффективность расхода топлива
высокая частота импульсов
недостатки (недоработки) устраняются
намного превышающая эффективность
постоянный объём сгорания
по сравнению с чем-либо
для широкого применения
облегчить взлёт
пульсирующие взрывные волны
клапаны двигателя

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