Study of flow characteristics and features of joint operation of the fuel manifold of the main combustion chamber of the Al-31F engine

Abstract

The article presents the findings of an experimental investigation into the flow characteristics of the initial and subsequent stages of a single nozzle within the fuel manifold of the main combustion chamber of the AL-31F turbofan engine. The flow characteristics of the second circuit injectors were found to exhibit unexpectedly low pressure drops at ultra-low pressures. The nature of the liquid flow from these injectors and its interaction with the air flow in the vortex burner were also determined through experimentation. A geometric model of the fuel manifold was constructed. A mathematical model for calculating the hydraulic characteristics of the fuel manifold was developed. The values of the flow characteristics obtained from the experimental results were employed as boundary conditions for the numerical modeling of the hydraulic characteristics of the fuel manifold in the ANSYS CFD environment. The results of the numerical fuel injection process during the joint operation of two cascades of the fuel manifold and the process of filling the second cascade were visualized. It has been established that during steady-state operation of an aircraft engine, the second stage of the fuel manifold operates at ultra-low pressure drop values, which results in a deterioration in the uniformity of fuel injection and, subsequently, an increase in the resulting temperature field irregularity. The modeling was performed with consideration of the force of gravity, which enabled the determination of the nature of the manifold filling and the distinction in the values of the mass flow rate of fuel in individual fuel manifold nozzles.