Оцінка тяги закапотованого співвісного гвинтовентилятора

Abstract

One of the basic requirements for existing and future aircraft engines is high specific power, low specific fuel consumption, and low noise level. The current work evaluates the thrust of a ducted coaxial propfan. A coaxial propfan was chosen as the object under study. The peripheral diameter of the first and second rows of the propfan reaches 4.5 m. The number of blades of the first row of the propfan is 8, the second – 6. The duct had a length of 3.214 m and a maximum profile thickness of 0.23 m. For this study, a model of a coaxial propeller fan was made for a numerical experiment. The model created for the study was a cylinder with a radius of 75 m and a height of 150 m. A model of an open coaxial fan and a ducted coaxial fan was created in this cylinder. The simulation of the flow in a ducted and open coaxial propfan was carried out for a flight altitude of H=7534 m at a rotational speed of the first and second rows of the propfan at 850 rpm. The input Mach number was 0.52. Based on the results of the study, a histogram for evaluating the thrust of the ducted and open coaxial propfan was constructed. The simulation of the flow in assessing the thrust of a ducted and open coaxial propfan was carried out under the same flight conditions. The results of the study showed that the presence of a duct gives a fairly large increase in thrust - the thrust of a coaxial propfan increases by 82 %. However, note that the calculations do not consider the drag that the duct will create. Evaluation of the drag of the ducted is the next task of the study. The resulting visualizations of the flow around an open and ducted coaxial propfan demonstrate qualitative and quantitative changes in the values of the parameters under study during flow. It can be seen that in the presence of a duct, the total pressure behind the propfan increases significantly. Increasing the thrust of a ducted coaxial propfan makes it possible to reduce the rotational speed of the propfan to provide thrust similar to that of an open propfan, which will improve the acoustic characteristics of the propfan. Also, the acoustic radiation can be reduced by placing sound-absorbing structures in the duct.