ВВС США заинтересовались двигателями SABRE (Synergetic Air-Breathing Rocket Engine)

Boeing инвестировала в компанию Reaction Engines, которая разрабатывает гибридный ракетный двигатель

 

Он сможет работать как в атмосфере, так и в вакууме

 

Как стало известно на днях, компания Boeing в лице своего подразделения Boeing HorizonX, совместно с Rolls-Royce и BAE Systems инвестировала в компанию Reaction Engines 37,3 млн долларов. Факт участия Boeing в данном случае интересен не так сильно, как причина, по которой компания вложила деньги в Reaction Engines.

 

Причиной является разработка Reaction Engines — двигатель Synergetic Air-Breathing Rocket Engine (SABRE). Это гибридный реактивный ракетный двигатель, особенностью которого будет служить эффективная работа как в пределах атмосферы, так и вне её. В частности, в атмосфере двигатель сможет развивать скорость до 5 Махов, а в вакууме — до скорости, эквивалентной 25 Махам.

 

 

Подобный двигатель позволит создавать одноступенчатые ракеты-носители, так как не нужно будет использовать два двигателя для разных режимов. Кроме того, такая силовая установка позволит сделать ракеты компактнее и дешевле. Последнее будет достигаться не только за счёт уменьшения габаритов ракеты и упрощения её конструкции, но и благодаря тому факту, что эти двигатели будут многоразовыми.

 

Что касается технической части, вот что сказано по этому поводу в «Википедии»: «В основные (ракетные) камеры сгорания (их по 4 в каждом двигателе) подаются топливо (жидкий водород) и окислитель — либо атмосферный воздух, нагнетаемый турбокомпрессором и сильно охлаждаемый при прохождении через теплообменник (воздушно-реактивный режим), либо жидкий кислород из баков (ракетный режим). Турбокомпрессор приводится во вращение газовой турбиной, на которую в качестве рабочего тела подаётся нагретый гелий, получающий тепло от охлаждаемого в теплообменнике воздуха и дополнительно разогреваемый при охлаждении им сопел. Затем гелий охлаждается частью топлива — жидкого водорода (гелиевый цикл). Кроме того, двигатели оснащены вспомогательными прямоточными камерами сгорания, питаемыми воздухом из внешних обходных каналов и используемыми для сжигания излишков водорода, испаряющегося при охлаждении воздуха, не попавшего в теплообменники двигателей во время их работы в воздушно-реактивном режиме».

 

 

Ранее сообщалось, что испытания полноценного экземпляра такого двигателя намечены на 2020-2021 год. На данный момент Reaction Engines привлекла уже почти 150 млн долларов инвестиций.

Источник: https://www.ixbt.com/news/2018/04/16/boeing-reaction-engines.html

Получены разрешения от ESA и UKSA на испытания SABRE.

https://newatlas.com/air-breathing-sabre-engine-testing/58874/

Reaction Engines’ precooler has successfully run at Mach 5 temperatures, validating for the first time the capability of the novel heat exchanger design to operate at hypersonic flight conditions for atmospheric and space access applications.

The breakthrough test is pivotal to Reaction’s goal of using the lightweight heat exchanger (HTX) to boost high-speed turbojets for supersonic and hypersonic vehicles as well as for developing the company’s Synergistic Air-Breathing Rocket Engine (Sabre), which is targeted at low-cost, repeatable access to space.

- Mach 5 run paves the way for an integrated engine tests

- Gas temperature dropped from 1,000C to 100C in less than 1/20th sec.

Forming the culmination of a DARPA contract awarded in 2017, the Mach 5 run took place in the second week of October at the company’s TF2 test facility at the Colorado Air and Space Port near Watkins. Established on an all-new site just 22 months ago, the high-speed test comes seven months after the heat exchanger demonstrated operation at supersonic conditions equal to Mach 3.3. Heated air for the tests is generated by a General Electric J79, which operated at military power for the supersonic runs and in maximum afterburner for the tests up to Mach 5.

“We had high confidence but, until these tests over the past six months, there was just an assumption this technology would work at these high temperatures because there was no way to test it. So, I’m very glad it came off,” says Adam Dissel, president of Reaction Engines. Although initial tests in the UK in 2012 using a Rolls-Royce Viper turbojet demonstrated the ability of the HTX to chill air from ambient to under -120C (-184F), the larger-scale evaluations in the U.S. were viewed as the true acid test. “Taking the whole device up to these high temperatures as part of an integrated system is quite a design challenge,” he adds.

Describing the test result as a “major moment in the development of a breakthrough in aerospace technology,” Reaction Engines CEO Mark Thomas says: “We are seeing significant interest from a range of potential customers and technology partners.”

The precooler is made up of 16,800 thin-walled tubes (equal to more than 27 mi. of tubing) through which helium is pumped to remove heat. In the Colorado tests, the heat is rejected into water that boils off to the atmosphere, but in a Sabre it would be cooled by a hydrogen heat exchanger. “In the Mach 5 test, the temperature was reduced from around 1,000C to roughly 100C in less than 1/20th of a second,” says Dissel.

The final amount of cooling is dependent on the temperature of the heat sink used in the test. “In the current campaign, we rejected heat to a water boiler; the test done several years back in the UK rejected heat to a liquid nitrogen boiler,” he notes. “The ultimate choice for a flight system as to what temperature you cool the air down to is an integrated trade study depending on the application. Our current thoughts are that for either Sabre or precooled jet engines, you would likely not need to cool down to cryogenic temperatures.”

For high-speed turbojet applications in the nearer term, the HTX significantly reduces compressor delivery temperature (T3). This maintains sea-level conditions in front of the compressor over a wider range of speeds, thus maximizing net thrust. For space access applications, the HTX will pass chilled air to a turbo-compressor and into a rocket thrust chamber, where it will be burned with subcooled liquid hydrogen fuel.

Following the activation of the afterburner system on the J79, the team took a build-up approach toward hitting the high Mach target. “Through early summer, we tested multiple points of the envelope, eventually running up to about Mach 4.3. We tested at various airflow rates with varying coolant rates of helium mass flow passing through the precooler,” says Dissel.

The approach yielded “a good understanding of the physics and the air-pressure drop across the matrix as it transitions across the precooler,” he adds. The results also indicate the HTX responds quickly to variable airflow conditions. “The precooler has behaved amazingly well,” Dissel says. “It adapts to changing flow nearly instantly, so that was good to see. It’s part of a function of how light it is, so the precooler is not relying on thermal inertia to survive.”

By the time tests got to Mach 4.3 levels, however, the group realized that the test infrastructure was approaching heating limits before the precooler could reach its planned test condition. “The challenge we have had on the facility side was tricking it into thinking it’s flying on a Mach 5 aircraft. To ensure we had the right condition, we took a couple of months to make some upgrades and added insulation blankets to reduce the heat transfer into the walls of the airflow ducts and plenum,” he adds.

The upgrade, which also involved increasing the mass flow of the helium cooling circuit, made sure “we were ready to go for gold on the max condition,” Dissel notes.

Reaction Engines is now conducting a detailed examination of the HTX prior to assembling updated versions more tailor-made for testing with jet engines—though this time in front of the engine rather than sitting in its exhaust. “We’d like to apply the learning from this test to see what can be done for precooled propulsion next,” says Dissel. “We are very interested in the ability to enable a fast jet engine and to be able to demonstrate that here on the ground and then transition that to flight-test opportunities. That’s the next progression, and this buys down a major risk element of the Sabre engine.”

For an initial step, Reaction is studying the relatively small GE J85. “That’s our candidate at the moment. If we can show a jet engine operating at 20-40% past its design point, that would help prove the value proposition as quickly as possible,” he adds. The current precooler is sized for airflow rates of around 30 lb./sec. making it suitable for such an engine.

In the UK, where work is underway toward testing the core of the Sabre engine in 2021, Reaction is also starting an effort to evaluate the precooler with a Eurojet EJ200 under a £10 million ($13 million) project announced in July by the Royal Air Force’s (RAF) Rapid Capability Office. The project, which also involves BAE Systems and Rolls-Royce, is intended to inform engine studies for Britain’s future combat aircraft, the Tempest.

The RAF says the effort could also lead to lower costs both in terms of purchase and maintenance, a key focus of Britain’s Future Combat Air System Technology Initiative to research and develop new technologies that can be injected into UK Eurofighter Typhoons and Lockheed Martin F-35s as well as potentially feature in a future Typhoon replacement in the 2030s.

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