Open AccessBased on the analysis results from the patent search and review of domestic and foreign publications in variable cycle engines (VCE) was created a classification of the possible schematic diagrams of VCE realizing three-stream engine technologies (the adaptive low pressure compressor (LPC) with air extraction behind stages, FLADE compressor, various feeding types of extraction air to the flowing path of the engine, etc.).
To estimate a three-stream engine application as a part of the power-plant (PP) efficiency, was chosen an adaptive LPC technology scheme with the third contour air bypass beyond the critical section of a basic jet nozzle for which a mathematical model (MM) of the PP has been created on the basis of one-dimensional MM of the engine. The MM of the PP included 3D modeling results of the air inlet, the LPC with various air extractions to the third contour, and the jet nozzle taking into account the interaction between the basic stream and the third contour stream.
The predicted performance of an air inlet have been used to estimate the changes in a total pressure restoration coefficient and an additional resistance coefficient along «a fluid contour» when air extraction is included in the third contour in several cruiser modes of flight.
An integrated characteristic of the LPC has been received at various points and levels of air extraction to the third contour, and parameters of extracted air (depending on the point and amount of air extraction, and also on the fan operating mode) have been calculated. When analyzing the obtained calculation results, the effect of pressure lines displacement to the right (towards the large reduced rates), growth of efficiency values, and also position displacement of its maximum value to the left (towards the descent reduced rates) has been found.
To estimate how air extraction of the third contour between the plates of an adjustable supersonic nozzle impacts on its aft deck resistance various parameters of the flowing out air in subsonic cruiser mode of flight have been calculated.
As a result of calculations according to the PP MM, under near-the-earth conditions of the subsonic cruiser flight, the effective specific fuel consumption has been reduced by 12,5 %.
The results reached allow us to expect significant subsonic effective fuel conservation of the three-stream engine. To prove the calculated results it is further necessary to achieve them under full-scale conditions using the engine-demonstrator.