Stabilization and Dynamic of Premixed Swirling Flames

Prevaporized, Stratified, Partially, and Fully Premixed Regimes

Paul Palies

• Editorial: Academic Press
• Año: 2020
• ISBN:
  9780128199978
• Categoría: Tecnología e ingeniería
• Categoría: Ingeniería aeronáutica y astronáutica

Stabilization and Dynamic of Premixed Swirling Flames: Prevaporized, Stratified, Partially, and Fully Premixed Regimes focuses on swirling flames in various premixed modes (stratified, partially, fully, prevaporized) for the combustor, and development and design of current and future swirl-stabilized combustion systems. This includes predicting capabilities, modeling of turbulent combustion, liquid fuel modeling, and a complete overview of stabilization of these flames in aeroengines. The book also discusses the effects of the operating envelope on upstream fresh gases and the subsequent impact of flame speed, combustion, and mixing, the theoretical framework for flame stabilization, and fully lean premixed injector design.

Specific attention is paid to ground gas turbine applications, and a comprehensive review of stabilization mechanisms for premixed, partially-premixed, and stratified premixed flames. The last chapter covers the design of a fully premixed injector for future jet engine applications.

• Features a complete view of the challenges at the intersection of swirling flame combustors, their requirements, and the physics of fluids at work
• Addresses the challenges of turbulent combustion modeling with numerical simulations
• Includes the presentation of the very latest numerical results and analyses of flashback, lean blowout, and combustion instabilities
• Covers the design of a fully premixed injector for future jet engine applications

1

The combustor

Abstract

The first chapter of this book is dedicated to the gas turbine engine, an essential technology for the energy and transport sectors. This chapter begins by describing the overall principle of the gas turbine engine with respect to selected propulsion and electricity generation systems. Their respective specificities are outlined. The key performance metrics of these technologies are introduced along with the engine station numbering and the standard atmosphere model that are used to determine these performances. These descriptions are completed by a presentation of the multiple modules of the gas turbine engines with a focus on the combustor module. Elements of thermodynamics and nonreacting fluid mechanics are also included, in terms of both global and local budgets. Secondly, the role and requirements of the combustor are summarized and the design space for aircraft application is introduced. The design space is at the intersection of engine operating conditions, combustion physics, and combustor requirements. Thirdly, this chapter introduces the various existing and future combustor architectures corresponding to several technology readiness levels: rich-burn quick-quench lean-burn (RQL), lean direct injection (LDI), the low swirl injector (LSI), lean premixed/prevaporized (LPP), and lean fully premixed (LFP). The emphasis of the chapter is on the description of the combustor environment and its subsequent impact on the combustion processes. The last section details the operating conditions along the flight envelope for a typical geared turbofan engine, with particular focus on future fully premixed combustion systems. This initial chapter situates the main technological aspects that will be used throughout the book.

Keywords

gas turbine engine; fan; compressor; combustor; turbine; thermodynamics; propulsion; power generation; efficiencies

1 Overall principle of the gas turbine engine

1.1 Generalities and overall description

This section describes the principle of the gas turbine engine. The main goal of the gas turbine engine is to provide momentum to the fluid at rest to generate power or propulsion. Indeed, in the laboratory frame of reference and considering cruise conditions: for an aircraft engine or nominal conditions for a stationary gas turbine, the air is at rest upstream the engine. The momentum is transferred firstly to the air at rest by the rotating inlet fan and secondly to the ambient air by the exhaust jet. These two momentum exchanges are the two sources of thrust for current commercial subsonic turbofans (the thrust from the fan is dominant). The goal of the gas turbine engine is therefore to generate these two sources of momentum: fan rotation and exhaust jet. To achieve this goal, the turbofan engine has two distinct and linked flow paths: the so-called cold air flow path (also referred to as bypass flow), where the fan driven by the turbine transmits its momentum, and the so-called hot air flow path (also referred as core flow) due to the combustion inside the combustor, where the engine core transmits its momentum. The core is responsible for the rotation of the fan and induces the exhaust j...