General aviation engine development summary

General aviation engines and their characteristics

Due to the wide range of general aviation, the configuration and characteristics of general aircraft vary greatly. In terms of aircraft types, it can be divided into fixed-wing aircraft and rotorcraft (mainly referring to helicopters, multi-rotors are currently mainly used in drones) Two major categories. Fixed-wing aircraft can be mainly divided into piston aircraft, turboprop aircraft and jet aircraft according to engine type. Helicopters can be divided into piston helicopters and turboshaft helicopters according to the type of engine used.

1.Development characteristics

General aviation engines are used in many ways, from pistons, turbojets, turbofans, turboprop, turboshafts and even propeller fan engines, they are all the objects selected by general aviation aircraft; from size or thrustIn terms of (power) size, the characteristics of general aviation engines are mainly small and medium-sized. Specifically manifested as the following points:

（1) Piston engines dominate

From the perspective of aviation engines, turbofan engines for civil aviation transportation and military aviation are absolutely mainstream; while general aviation engines have piston type, turboprop type and turbofan type coexist, and piston type engines are mainstream;

（2) Broad development prospects

In July 2012, the State Council officially issued the "Several Opinions on Promoting the Development of the Civil Aviation Industry", which clearly pointed out: Increase the intensity of low-altitude airspace management reform and vigorously develop general aviation. In 2015, the "Proposal of the Central Committee of the Communist Party of China on Formulating the 13th Five-Year Plan for National Economic and Social Development" proposed: expand the space for infrastructure construction. Accelerate the improvement of infrastructure networks such as water conservancy, railways, highways, water transportation, civil aviation, general aviation, pipelines, and postal services. Improve the energy security reserve system.

On May 17, 2016, the General Office of the State Council issued the "Guiding Opinions on Promoting the Development of the General Aviation Industry" (hereinafter referred to as the "Opinions"), which made specific arrangements for further promoting the development of the general aviation industry. The "Opinions" proposes that by 2020, more than 500 general airports will be built, and basically achieve general airports or transportation airports that take into account general aviation services in cities at or above the prefecture level.

It is obvious that aero engines, one of the core contents of general aviation, will usher in new development opportunities and broad development prospects with the booming development of the general aviation industry.

Development trend of piston aircraft engines

Piston engines have improved as people's requirements for engine performance change. picture1The technological development of piston engines is demonstrated.

picture1Piston engine technology development

（1) Multi-stage supercharge technology has begun to be widely used

As the altitude increases, the air density and temperature decrease, resulting in a decrease in the amount of air entering the cylinder, a decrease in the air-fuel ratio, and a decrease in the compression end temperature, which deteriorates the combustion process, decreases in the engine's power and economy, increases in the thermal load and increases in the exhaust temperature, resulting in a decrease in the reliability of the aircraft engine's operation.

Through boosting technology, the air density can be improved, the engine's power can be quickly restored, the engine's empty performance can be improved, and the aircraft can be satisfied with the airplaneRequirements for use above 8km. Superchargers include single-stage pressure ratio technology, integrated design technology of multi-machine boosting system, multi-stage boosting system adjustment and control technology, and system trustworthiness technology under relatively empty conditions, etc.

（2) Aviation heavy oil engines have gradually become the mainstream of piston aircraft engines

The fuel supply of aviation heavy oil is guaranteed and versatile. It is safer than energy compared to gasoline, transportation and storage, and it also comes with turbocharged., with superior air performance and improved combustion efficiency, can greatly improve the performance of light aircraft, and become the type of piston engine that the world's aviation powers focus on developing. The development of aviation heavy oil piston engines requires further improvements in trustworthiness technology, booster matching technology and spray combustion technology under the premise of lightweighting.

（3) High demand for low-cost piston engines

Proposed by developed aviation countries such as the United StatesThe "Advanced General Aviation Transportation Plan" and other ideas point out that general aviation will be popularized in the future, and that small aircraft transportation systems are the fourth revolution in high-speed transportation. One of the basis of this idea is low cost. Compared with gas turbine engines, although the piston engine, as the main force of general aviation, has cost advantages, it is necessary to further reduce costs through design and manufacturing, reduce procurement and maintenance costs, and eliminate obstacles to the development of general aviation.

The article is reproduced fromFar-looking Think Tank