Scaling of the Two-Phase Flow Downstream of a Gas Turbine Combustor Swirl Cup: Part I—Mean Quantities

H Y Wang,W A Sowa,V G Mcdonell,G S Samuelsen

doi:10.1115/1.2906730

H Y Wang, W A Sowa + Show 2 more

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https://doi.org/10.1115/1.2906730

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Abstract

A production gas turbine combustor swirl cup and a 3×-scale model (both featuring co-axial, counterswirling air streams) are characterized at atmospheric pressure. Such a study provides an opportunity to assess the effect of scale on the behavior of the continuous phase (gas in the presence of spray) and droplets by comparing the continuous phase velocity, droplet size, and droplet velocity at geometrically analogous positions. Spatially resolved velocity measurements of the continuous phase, droplet size, and droplet velocity were acquired downstream of the production and 3×-scale swirl cups by using two-component phase-Doppler interferometry in the absence of reaction. While the continuous phase flow fields scale well at the exit of the swirl cup, the similarity deviates at downstream locations due to (1) differences in entrainment, and (2) a flow asymmetry in the case of the production hardware. The droplet velocities scale reasonably well with notable exceptions. More significant differences are noted in droplet size, although the presence of the swirl cup assemblies substantially reduces the differences in size that are otherwise produced by the two atomizers when operated independent of the swirl cup.

Highlights

Co-axial, counterswirling air streams have been studied for a variety of applications in combustion and other systems
A portion of the droplets convect directly downstream while the remainder impinge onto the inner surface of a primary venturi, form a thin liquid film, and are re-atomized in the shear field produced between the two counterswirling air streams
Data are provided for the following representative droplet size groups:

Summary

Introduction

Co-axial, counterswirling air streams have been studied for a variety of applications in combustion and other systems. The time-averaged droplet size and velocity distributions are compared downstream of the production hardware and the 3 x-scale model of the swirl cup. These data, along with the mean axial and radial velocity data, reveal a disproportionate entrainment of medium-sized droplets in the 3 x -scale case.

Results

Conclusion