Авіаційно-космічна техніка та технологія (Aug 2021)
Performance assessment of the ducted propfan of the turbofan engine with ultra-high bypass ratio
Abstract
In many respects, the efficiency and economy of the aircraft are determined by the parameters and characteristics of the power plant. The analysis of trends in the world engine building shows that an increase in the bypass ratio can significantly increase the efficiency of engines. One of the possible technical solutions to ensure the high performance of the perspective engines with an ultra-high bypass ratio is the use of a ducted propeller or propfan. This solution allows you to reduce acoustic radiation. In addition, the main advantage of the ducted propfans is a certain increase in thrust for the same consumed power. When flowing around a ducted propfan, a significant suction force arises on the nose of the profiled ring, the projection of which on the direction of movement provides a positive thrust of the ring. The presence of a duct also leads to a decrease in the final loss of the propeller, which, in turn, leads to an increase in the efficiency of the engine. Ducted and unducted propfans with the same blade row are investigated to assess the characteristics of a ducted propfan. The researches were carried out by the method of numerical experiment. The object of the research is a propfan with an inlet diameter of 2.924 m and the number of blades of 14 for a turbofan engine with a bypass ratio of m = 30. To research the propfan characteristics, a cruising mode of operation was selected in the range of revolutions n = 1500 ... 1650 rpm. with Mach numbers at the input from M = 0.54 to M = 0.8. In this work, the calculation did not take into account the resistance force of the duct. For a qualitative assessment of the flow in the propfan, visualization of the flow lines in the ducted and unducted propfan was obtained. The analysis of the research results showed that for all modes of operation the ducted propfan has a thrust force higher than the unducted propfan. The increase in thrust load reaches 71 ... 76 %. Visualization of the flow lines when flowing around a ducted and unducted propfan showed that the presence of a duct improves the internal aerodynamics of the propfan.
Keywords
