Forming of ducted axisymmetric supersonic air inlets

Abstract

Relevance of the research. The efficiency of fuel chemical energy conversion into mechanical motion of a supersonic aircraft is determined by energy losses due to aerodynamic drag of the aircraft and total pressure losses in the air inlet of jet engine. Therefore, ceteris paribus the aircraft with lower level of these losses will be more energy efficient. Significant increase in energy efficiency is expected from the use of axisymmetric isentropic ducted air inlets. In the framework of the non-viscous flow, a numerical method is offered for these air inlets with a contoured central body and a cylindrical shell designing. The main aim of the study. Currently there are no designing methods for axisymmetric isentropic ducted air inlets without elements projecting over a cylindrical body of the aircraft. Therefore, the aim of the study is to develop a methodology for designing such inlets. The methods used in the study. Numerical implementation of the characteristics method for isentropic flow is used. The proposed method involves the decision of two problems. In the first problem a flow line around the given focus point of characteristics is plotted which starts at a break point of central body. In the second problem the rest of the contour is calculated using the reversed flow in an annular nozzle with a cylindrical shell. Simultaneously with the decision of the second problem, the position of the shell is determined. The central body can contain angular points at the edges of the contour. If we use an intermediate flow line then the central body will be smooth. The results. The authors developed the methodology for calculating different axisymmetric supersonic air inlet contours, which geometrical characteristics are uniquely described by the original data.

Keywords

• energy efficiency
• supersonic flow
• ducted axisymmetric air inlet
• ideal perfect gas
• method of characteristics
• isentropic flow