Flame Transfer Function Measurement of a Hydrogen-Blended Sequential Combustor

TL;DR

This study experimentally measures the flame transfer function of a hydrogen-blended sequential combustor, analyzing how hydrogen addition affects thermoacoustic stability and modeling the FTF with a distributed time delay approach.

Contribution

It provides the first experimental FTF measurements for a hydrogen-blended sequential combustor and introduces a DTD model fitting the FTF with insights into hydrogen effects.

Findings

Hydrogen blending influences the FTF characteristics.

The DTD model accurately fits the measured FTF.

Model parameters correlate with chemiluminescence data.

Abstract

The flame transfer function (FTF) relates acoustic perturbations and the coherent heat release rate response. This frequency-dependent function governs the thermoacoustic stability of a combustor. The FTF measurement is therefore of great interest for predicting the stability of the a practical combustor connected to the engine's compressor and turbine. In this study, the flame transfer function of the sequential flame of an atmospheric constant pressure sequential combustor (CPSC) is experimentally measured. The thermal power of both the first- and second-stage flames is kept constant and their ratio is fixed at 1:1. The effects of hydrogen blending in the first and second stage fuel mixture on the sequential FTF are analyzed. The FTF of the sequential flame is fitted with a distributed time delay (DTD) model with two pulses. The trends of the model parameters obtained are consistent with the chemiluminescence OH* of the sequential flame.