Technical Notes on Next Generation Aero Combustor Design-Development and Related Combustion Research

This book aims to identify that extra high-pressure ratio (such as about 70) civil aero-engine low emissions combustors and extra high fuel-air ratio (FAR) (such as FAR>0.051) military aero-engine combustors make up the next generation of aero combustors. The aerothermal design of these combustors is very different from previous combustors, and the major design points are proposed. Two types of high-pressure low emissions combustor design have been suggested: one is without fuel staging, and the other is with fuel staging. The high FAR combustor design is brand new.

The layout of the next-generation aero combustor is very different. There are no primary holes, no intermediate holes, and no dilution holes. They all have direct mixing combustion. For low-emissions combustors, it is lean, direct mixing (LDM) combustion. For high-FAR combustors, it is stoichiometric direct mixing combustion. As a result, combustion air fraction is very high (such as >75%). That will induce idle condition lean blowout (LBO) issue.

The present book has proposed several design approaches to solve idle LBO issues, which are effective. Pilot fuel-air combustion is designed at idle conditions. For civil combustors, the maximum condition is designed for low emissions. In contrast, the maximum condition for the high FAR combustor is designed for non-visible smoke, low luminous flame radiation, and good combustion efficiency. The fuel-air module configuration is designed for each type of combustor, which is the essential part of combustor design. The brand-new combustor cooling design has used a compound angle tangential inlet cooling hole configuration. Such a cooling design provides high cooling effectiveness. The diffuser configuration is totally new. It is an air bleeding diffuser, directly stretching forward to contact the dome. The bled air flows to the annular channel as cooling air.

Aero combustor development is discussed in this book. In particular, the combustor developments from technology readiness level (TRL) 3 to TRL level 6 have been discussed in detail. Also reported is the technology to run combustor development tests correctly. Three topics of related combustion research by the present author are summarized in the brochure. They are:

a) Fuel injection and co-flowing air combination. The key point is that for next-generation combustor development, the designer should think about atomizatiInstead. The combination of fuel injection and co-flowing air should also be considered together as a whole device.
b) Fuel spray evaporation calculation, the key is an engineering calculation of multi-component fuel evaporation shall be used.
c) Non-luminous flame radiation calculation, which has been significantly updated.

The present book summarizes the author’s ten years of study on next-generation aero combustors after retirement. It represents an advanced aero combustor technology level.