In turbojet engines, low-viscosity oils are used, and in turboprops, they are more viscous, which is due to the use of a propeller gearbox in these engines, which requires oils with increased bearing capacity.In aviation, there are two types of gas turbine engines - turbojet and turbo screw.Depending on the type of technology, aviation oils are conventionally divided by application areas into oils for piston and gas turbine engines of aircraft and various units of helicopters.

Oils for piston engines

To ensure engine lubrication at high temperatures, pressures and loads, highly viscous oils are used that have been specially cleaned. Such oils should have high lubricating ability, not be aggressive to metals, alloys and other structural materials and have sufficient stability against oxidation at high temperatures and in storage conditions.In piston engines, oils operate under difficult conditions created by high temperatures in the area of ??piston rings, the internal part of pistons, valves and other parts.

Oils for turbojet engines

Due to the design features of gas turbine engines (GTE), the operating conditions of the lubricating oils in them differ significantly from the operating conditions of the oils in piston engines. Unlike a piston engine, the lubricating oil in a gas turbine engine is isolated from the combustion chamber (fuel combustion zone); in addition to toga, in the most critical friction units, rolling friction is mainly realized, and not sliding, as in piston engines (the rolling friction coefficient is an order of magnitude lower than the sliding friction coefficient). The turbocharger shaft in a gas turbine engine is well balanced and, at a high speed and high axial and radial loads, works without abrupt variable loads.

DPA OILS FOR AIRCRAFT ENGINES

Modern gas turbine engines are characterized by harsh operating conditions: high temperatures - up to 300 ° C and above, high turbine speeds - 12000-20000 mshg1. The tension of the oil under such conditions of operation of the gas turbine engine is determined by the amount of heat that must be removed from the friction surfaces of the parts, and other things being equal, is characterized by the speed of pumping oil through the engine.

The temperature of the oil at the inlet to the gas turbine engine ranges from 20 to 50 ° C, and at the outlet it depends on the engine tightness. In the engines of aircraft flying at subsonic speeds, it does not exceed 125 ° C, and at a speed of flight with the number M * 2 it reaches 200 ° C.

The supply of oil to the friction units at the gas turbine engine is carried out not only to lubricate the friction surfaces, but also to remove heat from these units. To avoid overheating of the friction units, the oil is continuously supplied to the following engine elements: bearings, gears, contact seals and splined joints. The highest level of heat generation is in the angular contact ball bearings of gas turbine rotors, which absorb axial load, therefore more oil is supplied to them than to other elements with; 1

Aircraft jet engine oils are thoroughly tested. When evaluating the quality of the oil, possible operating conditions and the intensity of its operation in the engine are taken into account.

Lubricating oils for turbojet engines must meet the following requirements:

homogeneous and stable fractional composition, which determines the minimum evaporation of the fractions and preserves the viscosity characteristics of the oil during the entire time the engine is running

(it is advisable to use lubricating oils of narrow fractional composition);

high antioxidant properties and minimal oxidation in the engine at operating temperatures of 150-200 ° C and higher;

minimal foaming, high self-ignition temperature;

non-aggressiveness in relation to metals, alloys, rubber products, coatings, adhesives and other materials.

Turboprop oils

Petroleum and synthetic oils are used to lubricate these engines. The main lubricants are oil mixtures obtained by mixing at the places of consumption of aviation oils MS-8p and MS-20 in the following ratios (May. Share,%): 75:25; 50:50; 25:75. It is allowed to use MS-8rk oil as a part of oil mixtures. Thanks to the use of high-quality MS-8p oil, the quality of oil mixtures is significantly improved. Oil mixtures are prepared and monitored according to departmental instructions of the MGA *.minimal foaming and evaporation.inertness with respect to metals, alloys, rubbers, coatings, adhesives and other structural materials;resistance to oxidation at high temperatures (150-175 ° C) and contact with air and various aviation materials;high antiwear and extreme pressure properties;gentle viscous-temperature curve and good pumpability at low temperatures;The requirements for turboprop engine oils are as follows:Design features of turboprop engines are associated with the presence of multistage gears (gears) in them, which are designed to transmit large forces and operate at high rotational speeds. To withstand such loads, shows operating experience, oils with high viscosity can. Therefore, oils with a higher viscosity are used for turboprop engines than for turbojets.

Oils for helicopters

To lubricate the helicopter transmission gearboxes, a wide range of oils for various purposes is used, the quality level of which is low. Since low-viscosity motor oils have insufficient lubricity, and high-viscosity petroleum oils have unsatisfactory low-temperature properties, oil mixtures are widely used to lubricate transmission gearboxes.In helicopters, oils are lubricated with engines, transmission reducers, and hinges of screw bushings. In the engines of MI-6 and MI-10 helicopters, MS-8p and MS-8rk oils are used, in MI-2 and MI-8 helicopters use B-ZV synthetic oil, in the turbocompressor part of the power plant of the MI-26 helicopter IPM synthetic isoparaffin oil is used -10. It is recommended to use PTS-225 synthetic oil in the engine and gearbox of prospective and newly designed helicopters.

Oils for gas pumping units

Gas pumping units (GPU) installed at compressor stations (CS) for various purposes are designed to compress natural gas for transportation through gas pipelines at ambient temperatures from -55 to + 45 ° С, GPUs are distinguished by the type of compressor drive ( superchargers): gas turbine driven by centrifugal superchargers from stationary gas turbine units (GTU) or from converted transport (aircraft and ship) gas turbine engines (GTE);

EGPA) with centrifugal blowers driven by electric motors;

piston (gas engine compressors), in which the piston compressor is made integrally with a gas engine.

oil cooling with minimal power consumption for its pumping;reliable operation in all modes - switching on, starting and emergency stop under changing external temperature conditions;

Oil systems are designed to provide lubrication of bearings and other friction pairs, cooling of gas pumping units (GPU), compressor shaft seal, operation of control and protection systems, as well as:

fire safety;

separation of gases, solids and water from oil;

the exception of the formation in the system of air jams;

oil warming up at startup (or when the unit is in the “hot reserve”);

differences in fueling;sufficient oil supply to run between discharge minimum costs (losses) of oil during operation;

tightness of the connection; ease of maintenance.sufficient strength and vibration resistance of system elements,