ELUCIDATION OF INTERNAL FLOW AND ITS EFFECT ON THE JET OF A TWIN-FLUID ATOMIZER FOR GAS TURBINE CROSSFLOW COMBUSTORS

Abstract

Conventional liquid fuel jet injection into a crossflow is widely used for large-scale power generation in gas turbine combustors. The authors proposed a new twin-fluid injection technique as a potential alternative and conducted a series of studies on the internal flow of the atomizer and liquid jet/spray characteristics. In this study, experimental and numerical studies were first performed on internal flow behaviors and liquid and atomizing air interactions. The important behaviors of the internal flow of the atomizer, such as the dynamic change in the liquid film thickness, the rapidly changing velocity of the wave front, and the liquid impingement distance on the inner wall of the atomizer, were measured by both the experiment and numerical analysis. Atomizing air generates a high-speed oscillating annular liquid film flow that flows at the exit of a twin-fluid atomizer. This dynamic of the annular liquid film is considered fairly advantageous for achieving good atomization, which is investigated by analyzing only the liquid's behaviors in jet/spray and twin-fluid injection in a crossflow. High-speed photography and image processing were applied to observe the liquid jet/spray phenomena in the crossflow and reveal the atomization characteristics such as jet/spray trajectories and breakup length. Furthermore, the atomizing air can dominate the trajectory of the liquid jet/spray in the crossflow. The twin-fluid injection provides improved atomization properties compared to conventional liquid-only injection.