Speaking of aviation engines, most people’s first reaction is that they are far behind the United States, at least 20 years. Is this really the case? This is not the case with
! Aviation engines are divided into many categories, such as piston engine , turboshaft engine, turboprop engine, turbojet engine, turbofan engine , ramjet engine , variable cycle engine , combined cycle engine, detonation engine.
It is undeniable that my country still lags behind the United States in several major categories of existing aerospace engines, but in terms of new concept engines, my country has great potential to catch up with and surpass the United States, such as detonation engines.
Screenshots of domestic pulse detonation engine research papers
1. What is a detonation engine?
detonation engine is a new power device based on the principle of detonation combustion. It uses high-temperature and high-pressure gas generated by pulse/continuous rotating detonation waves to generate thrust. The detonation engine is divided into pulse detonation engines according to different implementation methods. detonation engine (PDE), rotating detonation engine (RDE) and oblique detonation engine (ODE).
PDE requires ignition every time it detonates, while RDE only requires one detonation. Compared with PDE, RDE is lighter in weight, uses less fuel, but can generate greater thrust, with a thrust-to-weight ratio of up to 20. PDE and RDE are suitable for quasi-superior flight of Mach 5-6, while ODE can reach higher speeds of Mach 6-17. Therefore, research in the field of detonation engines in China and the United States has gradually turned to RDE and ODE.
continuously rotating detonation engine (RDE) can be used as commercial aerospace rocket power, high-speed drone power, gas turbine power, and is used in various rockets and missiles , near space vehicles, military aircraft, drones and other fields. The continuous rotating detonation engine has extremely high price competitiveness in commercial applications. Compared with other types of products with the same thrust, the cost can be reduced by more than half, and it has great military and commercial application value. The oblique detonation engine can be applied to the hypersonic aircraft . In the future, a new concept hypersonic passenger aircraft can even be developed based on this engine. It can reach the world in 2 hours. If applied to missiles, it will become a very difficult interception engine. Hypersonic weapons .
my country's oblique detonation engine principle prototype wind tunnel test photo
Once the RDE technology matures, this engine can also be combined with a turbofan engine to become the next generation aeroengine after the variable cycle engine, also known as the 7th generation aviation engine, also known as a self-supercharged engine. After ODE technology matures, it can become the first-level power for a two-stage combined aerospace aircraft. Therefore, the detonation engine is a type of future aviation power with very broad technical prospects.
2. Compared with turbofan engines, what are the advantages of detonation engines?
. High efficiency
The detonation engine can be regarded as constant pressure combustion, while the turbofan engine is constant volume combustion. Since the propagation speed of the detonation wave is extremely fast, reaching several kilometers per second, the entire combustion process of the detonation engine is close to constant pressure combustion. Since the thermal cycle efficiency of constant-pressure combustion is much higher than that of constant-volume combustion, reaching 49%, while the efficiency of constant-volume combustion is only 27%, the detonation engine also has the advantage of higher thermal efficiency than the turbofan engine.
. High thrust-to-weight ratio
Compared with traditional engines, detonation engines omit components such as compressors and turbines . They have the characteristics of simple structure, high thrust-to-weight ratio, and low cost. It is estimated that the thrust-to-weight ratio of the pulse detonation engine can reach 20, and may continue to increase in the future, while the thrust-to-weight ratio of the most advanced turbofan engines is only 12 to 13.
3, the flight envelope is wider, up to Mach 17.
Research shows that turbofan engines can only support aircraft flying in the Mach 0-3 speed range, and even turbine-ramjet engines can only fly in the Mach 0-5 speed range. However, the detonation engine can not only start at zero speed, but also have a maximum flight speed of more than Mach 5. The maximum flight speed of the oblique detonation engine can even reach Mach 17.
Schematic diagram of the working principle of oblique detonation engine
3. Who is making faster progress in Chinese and American detonation engines?
In the field of detonation engines, China and the United States have the most achievements and the highest technical level. By comparing the technological progress of China and the United States in the field of detonation engines, we can understand our country's technical level in the field of detonation. To avoid misunderstanding, hereby declares that the following information comes from public reports by domestic and foreign media.
. Research progress of detonation engine in the United States.
In 2003, Pratt & Whitney and Boeing Company jointly developed a full-scale, five-tube PDE verification prototype ITR-2 under flight intake conditions. The prototype completed a ground test under the conditions of simulated flight Mach number (Ma) 2.5 and a flight altitude of 12192m. It achieved stable operation at the single-tube operating frequency 80Hz, generated a thrust of about 6700N, and the minimum unit fuel consumption rate was only 0.08kg/( N·h). In addition, Pratt & Whitney's research also shows that when using hydrocarbon fuel, the maximum flight speed of pure PDE can reach Ma4. If hydrogen fuel is used, the flight speed can be increased.
PDE verification prototype ITR-2 test photo
On January 31, 2008, the PDE researched by the U.S. Air Force Research Laboratory (AFRL) conducted its first test flight verification at Mojave Airport, with a modified code-named "Long" The E-Z" small aircraft uses traditional turbofan engines for takeoff and landing. During the flight, the four-tube PDE is switched to work for 10 seconds. The flight altitude is about 30m, generating a thrust of more than 890N. This flight test has epoch-making significance for PDE engineering research and proves the potential of PDE as a power device.
In 2010, the University of Texas at Arlington designed and manufactured a large-size single-tube rotary valve pulse detonation engine. The diameter of the detonation tube is 10cm. It uses pre-evaporated kerosene as fuel and air as oxidant, and conducted ground verification tests. . The initial cycle test obtained a peak thrust of approximately 980N, and the flame propagation speed was 1288-1530m/s, reaching a sub-C-J detonation wave speed.
In May 2020, a research team at the University of Central Florida and a collaborative team on the Air Force Research Laboratory's Rotating Detonation Rocket Engine (RDRE) project claimed to have built and tested a working laboratory model. It is reported that the model is a 3-inch copper test stand that uses a mixture of hydrogen and oxygen as fuel and produced 200lbf of thrust during the test. The head of the research team claimed that the US Air Force aims to conduct a rocket launch flight test in 2025.
Test photos of the US-developed rotating detonation rocket engine
On May 17, 2021, engineers at the University of Central Florida have been developing an oblique detonation engine (ODE) that utilizes sustained, restrained explosions. Raw power. Now, they have successfully started the engine and captured and stabilized a fixed sustained detonation within the engine for the first time, converting its powerful detonation into thrust and successfully running it for 3 seconds.
. Research progress of detonation engine in China.
In 2002, Northwestern Polytechnical University was the first in China to complete the principle test of two-phase pulse detonation combustion, and then broke through the key technology of high-frequency operation. The highest single-tube two-phase detonation frequency is as high as 140Hz, which is the highest for a single tube when using gaseous fuel. The frequency has reached 200Hz; Conducted research on hybrid PDE and six-tube parallel PDE consisting of a turbocharger and pulse detonation combustion chamber; studied the effects of detonation method, air intake method, tail nozzle form, ejector, etc. on performance Impact, breakthroughs in many key technologies and mastering relevant design methods and rules of impact on performance. Based on years of accumulation, Northwestern Polytechnical University developed the first domestic PDRE ground demonstration and verification prototype and successfully conducted multiple ground rolling tests.
PDRE ground demonstration verification prototype developed by Northwestern Polytechnical University
Nanjing University of Aeronautics and Astronautics mainly focuses on the engineering application research of pulse detonation combustion technology, and the research content is highly practical and targeted.They have made significant progress in the research of key technologies such as pulse fuel supply, gas supply, ignition, single-stage detonation, two-phase detonation combustion, shortening the transition distance from deflagration to detonation, and completed the basics of a three-tube PDE with a rotary valve. Development of a principle prototype; research on a principle prototype of a pneumatic valve type PDE was also carried out. Under the test conditions of using gasoline as fuel and air as oxidant under normal temperature and pressure conditions, a fully developed pulse detonation wave was generated, and a maximum thrust of 1300N was obtained.
On March 6, 2017, the 21st International Space Shuttle and Hypersonic Systems and Technology Conference was held in Xiamen, my country. Jiang Zonglin’s team directly demonstrated a 660 mm diameter continuous rotating detonation engine experimental prototype.
In March 2019, the private enterprise Chongqing Thrust Power Technology Co., Ltd. completed the ignition test run of the first multi-tube parallel pulse detonation engine with the help of Chongqing University .
On December 11, 2020, Jiang Zonglin’s team from the High Temperature Gas Power Laboratory of the Institute of Mechanics, Chinese Academy of Sciences published an article in "Acta Aeronautica Sinica" , announcing that it had successfully tested a hydrogen-fueled oblique detonation engine in the M9 wind tunnel. Oblique shock waves can theoretically reach above M16.
In December 2021, media reports stated that the H1-M continuous rotation detonation engine independently developed by Chongqing Thrust to Weight Ratio Power Technology Co., Ltd. has completed dozens of hot test vehicle assessments, and the measured technical indicators have basically met the test design requirements. It is a thrust to weight ratio company. The subsequent development of the liquid rocket engine based on detonation propulsion laid the foundation for the stage.
H1-M Continuous Rotating Detonation Engine
On May 1, 2022, the flight test review meeting of Qing Aerospace Qinghang No. 1 rotating detonation ramjet engine was successfully held. The review experts unanimously believed that the Qinghang No. 1 rotary detonation ramjet engine successfully completed the scheduled scientific test tasks and achieved the test purpose. This is the first international flight test of a rotating detonation ramjet engine.
On July 30, 2022, The H1-M continuous rotation detonation engine developed by Chongqing Thrust Weight Bi Power Technology Co., Ltd. successfully completed the 100-meter orbital rolling test, with the maximum rolling distance reaching 100 meters. According to the report, the design thrust of the engine is 100N, the adjustment range is 40%~150%, the cumulative working times are more than 30 times, and the cumulative working time is about 300s. The test and assessment have met the standards. plans to launch the product in 2 years.
Since my country’s research progress in new concept engines is not fully disclosed, the above information is only public information, and my country’s actual achievements in the field of detonation engines will only be more.
Conclusion: Comparison shows that my country is already ahead of its American counterparts in the fields of rotating detonation engines and oblique detonation engines! Of course, my country's lead is not large, and we still need to make persistent efforts. Scientific research teams in European and American countries have always attached great importance to holidays, while our country's scientific research teams work more intensively, and many of them don't even have a few days off throughout the year. In addition, our country is the country with the most complete industrial system in the world. Therefore, if nothing unexpected happens, our country's research and development team will win the detonation engine development competition with a more complete industrial system and higher work intensity, taking an overall lead over their American counterparts!
