Авіаційно-космічна техніка та технологія (Aug 2024)
Evaluation of the characteristics of a ducted rotary propfan in flight conditions
Abstract
The subject of this study was the operating mode of the ducted rotary propfan. The object of this research was a ducted propfan with rotating blades of the impeller of an ultra-high bypass ratio turbopropfan engine (m=20). The purpose of this work was to evaluate the influence of the blade installation angle on the characteristics of the ducted propfan of an ultra-high bypass ratio turbopropfan engine (m=20) under flight conditions. To achieve this purpose, the following tasks were solved: modeling the flow in a ducted propfan at a height of H=11 km when changing the blade installation angle from +10 to -5º from the basic installation angle in the range of Mach numbers at the inlet from 0.5 to 0.7; calculate the efficiency, pressure ratio, and thrust force of the ducted propfan under the studied operating conditions. During the mathematical modeling of the flow in the ducted propfan, the resistance of the duct was not considered. The research was carried out using a numerical experiment method with ANSYS CFX. The geometric model of the ducted rotary propfan was built in the NX. The mesh model was made in the ICEM and has a block structure. Results: The blade installation angle is one of the important factors affecting the efficiency, the pressure ratio, the thrust force, and other parameters and characteristics of the ducted propfan of an ultra-high bypass ratio turbopropfan engine. The use of a rotary impeller in a propfan improves the propfan characteristics over the entire range of operating modes. In flight conditions at an altitude of 11 km in the range of Mach numbers at the entrance M=0.5...0.7, when turning the blade of the impeller ducted propfan to a negative angle β=-5º, the thrust force decreased by 6.2...10.8 %, and by changing the installation angle to β=+10º, the trust force decreased by 3.4...42.6 %. Changing the blade installation angle of the impeller-ducted propfan led to a decrease in the pressure ratio. The nature of the dependence is similar to the nature of the changes in trust force. The efficiency of the ducted propfan with a rotary blade increased from 8.7...9.1 % to 1.8...3.4 % for Mach numbers M = 0.5 and M = 0.6 when changing the installation angle of the impeller blade to β=+5º and β=+10º. When the blade was rotated by an angle of β=-5º, the efficiency decreased by 13.6%–14.5% for the entire considered range of Mach numbers. The scientific novelty and practical significance of the results of the research consists in the fact that new data have been obtained on the study of the characteristics (efficiency, pressure ratio increase, thrust force) of the ducted propfan of an ultra-high bypass ratio turbopropfan engine (m=20) and a rotary impeller blade. The received recommendations regarding the characteristics of the ducted rotary propfan of an ultra-high bypass ratio turbopropfan engine are expedient for use in the creation of promising aviation engines.
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