EXPERIMENTAL STUDY OF FLOW FIELD EFFECT ON SPRAY AND FLAME STRUCTURE IN SWIRL STABILIZED COMBUSTOR

摘要

The spatial distribution of spray plays a key role in liquid fuel combustion, which dictates the local mixture fraction and the flame temperature distribution in gas turbine engines. The swirling flow creates further decomposition of the spray droplets in liquid fuel gas turbine engine, which increases the surface area of the droplets. Turbulent mixing due to the swirling flow is essential for preheating of unburned products and flame holding in the combustor. A lab-scale swirl stabilized liquid fuel combustor was designed and fabricated with the geometric swirl number (SN) of 1. Combustor flow geometry involves internal spray from flow blurring twin-fluid atomizer, surrounded by swirling airflow which is confined with co-flow air to provide full optical access. At constant spray operating conditions, the swirl Reynolds number (Re) is increased whereas co-flow velocity was maintained constant at 0.4 m/s. An experimental study was carried out to understand the effect of Reynolds number on the aerodynamic structure of airflow, the spatial distribution of spray structure and kerosene flame structures using Particle Image Velocimetry (PIV) and direct imaging. The experimental results show that the flow structure and spray spreads radially with the increase in swirl Reynolds number and the corresponding core spray height decreases, which were evident from flame images.