Taming Combustion Instabilities by Design Principles

Introduction

Both the energy and aviation sectors rely on gas turbines, a combustion system continuously optimized since its invention during World War II. They constitute a main pillar for tomorrow's energy and aviation mix to tackle climate change.

Challenges in Combustor Design

However, fuel flexibility is stretched to its limits for conventional combustor designs. Combustion instabilities hinder a new generation of safe and low-emission gas turbines. This calls for disruptive design approaches to enforce crucially needed step-change technologies.

Objectives of TACOS

The overarching aim of TACOS is to break the bottleneck of combustion instabilities by novel, physics-driven design principles based on the latest theoretical findings. The combustion community, including myself, has discovered "exceptional points" (EPs), which are known from theoretical physics to feature intriguing, counter-intuitive physical properties.

Preliminary Results

Our preliminary results confirm that EPs:

1. Rapidly switch the combustor stability from unstable to stable.
2. Are well-controllable by both the acoustics of the chamber and the flame characteristics.

Key Goals

TACOS takes a leap forward and exploits the unique properties of EPs for the conception of novel combustors through three objectives:

• Objective A: Tailor the characteristics of both gaseous (land-based gas turbines) and spray flames (aeroengines) by carbon-free fuels (hydrogen + ammonia) and sustainable aviation fuels.
• Objective B: Optimize simultaneously the emission rates and the stability of the combustion chamber by designing the combustor close to the EP.
• Objective C: Quantify the design robustness by experiments at atmospheric and high-pressure conditions to learn design principles using explainable machine learning methods.

Expected Outcomes

As a result, TACOS will not only produce an unprecedented, computer-aided and optimization-centric design software for safe, robust, and clean gas turbines, but will also open a new research field on design principles and amplify fundamental breakthroughs in combustion instability (CI) research.