Breakup Mechanism of a Jet in the L-Shape Crossflow of a Gas Turbine Combustor

Abstract

Experimental investigations are conducted to determine the mechanism and characteristics of a jet in an L-shape crossflow simulating the radial swirl injector of a lean premixed-prevaporized (LPP) combustor. To simplify the radial flow of the actual injector while ignoring the centrifugal effect, the L-shaped 2D-channel is used for the crossflow, and water is used as a fuel simulant. The jet breakup is captured using a high-speed camera, and the density gradient magnitude is post-processed to clarify the spray. The Sauter mean diameter (SMD) of the spray is measured via a laser diffraction method with a helium–neon laser optical system (HELOS). The characteristics of the jet in the L-shape crossflow are compared with the characteristics of the jet in a typical crossflow through the flat channel. The results for different outlet heights of the L-shape channel (H/d0) and different injector positions (L/d0) are presented. A dimensionless number (τ) consisting of a time ratio is introduced to describe the jet characteristics. In a previous work, the spraying tendency was demonstrated for different injector positions. In addition, the effect of the recirculation area on H/d0 was empirically shown. H/d0 determines the size of the recirculation area, and the range of τ determines the jet breakup mechanism inside the L-shape channel. The results of this study present the breakup mechanism of the jet in the L-shape channel flow, which simulates a jet in a radial swirler injector for gas turbine engines. It is expected that these results can be used to assist in designing gas turbine engines with more combustion efficiency.

Investigation of Spray Characteristics for Detonability: A Study on Liquid Fuel Injector and Nozzle Design

“…When describing the internal oxidizer velocity (V g ) and fuel velocity (V l ) within the injector, their relationship with length can be expressed in terms of time. The study uses geometric variables within the injector as temporal terms and shares similarities with the research conducted by Choi et al [32]. By incorporating these terms, the relationship between film length and other terms is expressed as Equation ( 2).…”

“…The variables included in the equations encompass the gas Reynolds number, the liquid Reynolds number, the momentum flux ratio, the velocity ratio, and the length ratio. The SMD expressions are derived from prior research [32]; additionally, they incorporate a term representing the aspect ratio for predicting film length, accounting for the impact of the locations and the shapes of the fuel injection holes. The influence of Re e,g is notably pronounced across the terms in Equations ( 7) and ( 8), underscoring the critical role of Venturi nozzle velocity in determining spray characteristics.…”