Analyzing the Interaction of Vortex and Gas–Liquid Interface Dynamics in Fuel Spray Nozzles by Means of Lagrangian-Coherent Structures (2D)

Dauch Dauch,Koch Koch,Chaussonnet Chaussonnet,Rapp Rapp,Bauer Bauer,Ates Ates,Okraschevski Okraschevski,Kaden Kaden,Dachsbacher Dachsbacher,Keller Keller

doi:10.3390/en12132552

Abstract

Predictions of the primary breakup of fuel in realistic fuel spray nozzles for aero-engine combustors by means of the SPH method are presented. Based on simulations in 2D, novel insights into the fundamental effects of primary breakup are established by analyzing the dynamics of Lagrangian-coherent structures (LCSs). An in-house visualization and data exploration platform is used in order to retrieve fields of the finite-time Lyapunov exponent (FTLE) derived from the SPH predictions aiming at the identification of time resolved LCSs. The main focus of this paper is demonstrating the suitability of FTLE fields to capture and visualize the interaction between the gas and the fuel flow leading to liquid disintegration. Aiming for a convenient illustration at a high spatial resolution, the analysis is presented based on 2D datasets. However, the method and the conclusions can analoguosly be transferred to 3D. The FTLE fields of modified nozzle geometries are compared in order to highlight the influence of the nozzle geometry on primary breakup, which is a novel and unique approach for this industrial application. Modifications of the geometry are proposed which are capable of suppressing the formation of certain LCSs, leading to less fluctuation of the fuel flow emerging from the spray nozzle.

Highlights

In order to reduce the environmental impact of air traffic, aero-engine manufacturerers aim at higher efficiencies and less pollutant emissions
In a second step, detailed finite-time Lyapunov exponent (FTLE)− fields are presented, enabling a unique insight into the local breakup phenomena. This post-processing tool demonstrates the strengths of smoothed particle hydrodynamics (SPH) in combination with the Lagrangian-coherent structures (LCSs) concept regarding the analysis of liquid breakup phenomena
The effect of nozzle geometry on primary breakup is analyzed by means of FTLE− fields

Summary

Introduction

In order to reduce the environmental impact of air traffic, aero-engine manufacturerers aim at higher efficiencies and less pollutant emissions. Previous investigations by Lefebvre, Jones, and Knudsen [1,2,3] demonstrated that the formation of pollutants depends on the quality of the fuel spray injected into engine combustors. The characteristics of the fuel spray are significantly influenced by the geometry of the fuel spray nozzle. In order to optimize the nozzle geometry, a detailed understanding of the local flow field and the spray formation inside the nozzle is required. Difference between particles a and b gas Property of gas liquid Property of liquid nom Reference for EOS opt Optimal value for integration time re f.

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