Determining patterns in the influence of the number of blades in the ducted and unducted propfans on propfan thrust

Abstract

The efficiency of an aircraft engine is estimated by many parameters, one of which is the thrust force. Improving the efficiency of aircraft engines is an important task for engine building. However, questions remain regarding the effect of the number of blades on the change in the thrust of the ducted and unducted fans. In this work, the object of study is a propfan. 3 variants of the propfan with 8, 10, and 12 blades were investigated. The study was conducted by the method of numerical experiment. The aim of the work was to compile recommendations for choosing the number of blades in the ducted and unducted fans for motors with an ultra-high bypass ratio. That could make it possible to improve the efficiency of an aircraft engine with a propfan. Studies have shown that the number of blades in a propfan significantly affects the thrust force that it creates, as well as efficiency. With an increase in the blades of the ducted fan from 8 to 12, the thrust force increases to 38 %. With an increase in the blades of the propfan from 8 to 12, the thrust force increases to 36.9 %. An increase in the blades from 8 to 12 in the ducted fan leads to an increase in its performance, thereby improving efficiency by 2.4–5.7 %. When flowing around a propfan, it is possible to note the peculiarity that occurs when all three variants are streamlined – vortex traces of the blades in the peripheral parts. Visualization of current lines when flowing around an unducted fan with 8, 10, and 12 blades demonstrates a similar flow character. On the periphery, there are zones of higher speed but there are no zones with eddy formations. The resulting regularities of the influence of the number of blades on a change in the thrust of the ducted and unducted fans could improve the efficiency of the aviation power plant with an engine whose bypass ratio is ultra-high.