On the Analysis of Energy Efficient Aircraft Engines
Doktorsavhandling, 2017

Aero engine performance analysis is highly multidimensional using various measures of component performance such as turbomachinery and mechanical efficiencies, and pressure loss coefficients. Using conventional performance analysis, relying on only the laws of thermodynamics, it is possible to understand how the performance parameters affect the component performance, but it is difficult to directly compare the magnitude of various loss sources. A comprehensive framework has been detailed to analyze aero engine loss sources in one common currency. As the common currency yields a measure of the lost work potential in every component, it is used to relate the component performance to the system performance. The theory includes a more detailed layout of all the terms that apply to a propulsion unit than presented before. The framework is here adopted to real gases to be used in state of the art performance codes. Additionally, the framework is further developed to enable detailed studies of two radical intercooling concepts that either rejects the core heat in the outer nacelle surfaces or uses the core heat for powering of a secondary cycle. The theory is also extended upon by presenting the installed rational efficiency, a true measure of the propulsion subsystem performance, including the installation effects of the propulsion subsystem as it adds weight and drag that needs to be compensated for in the performance assessment.

Performance modelling

Aero engine


Aircraft engine

Installed propulsion

Ultra high bypass ratio

Exergy analysis

Engine weight estimate

Variable area fan nozzle

Multiple pivoting flaps

Translating cowls

HB4 Hörsalsvägen 8, Göteborg
Opponent: Professor Guillermo Paniagua, School of Mechanical Engineering, Purdue University, United States of America


Oskar Thulin

Chalmers, Tillämpad mekanik, Strömningslära

First and Second Law Analysis of Future Aircraft Engines

Journal of Engineering for Gas Turbines and Power,; Vol. 136(2014)

Artikel i vetenskaplig tidskrift

A Mission Assessment of Aero Engine Losses

ISABE-2015-20121,; (2015)

Paper i proceeding

First and second law analysis of intercooled turbofan engine

Journal of Engineering for Gas Turbines and Power,; (2016)

Artikel i vetenskaplig tidskrift

First and Second Law Analysis of Radical Intercooling Concepts

Journal of Engineering for Gas Turbines and Power,; Vol. 140(2018)p. 081201-081201-10

Artikel i vetenskaplig tidskrift

Thulin, O., Lundbladh, A., Grönstedt, T., Variable Area Fan Nozzle Weight and Performance Modeling

Lowering of fuel consumption is of paramount importance in the aerospace industry to reduce cost and emissions. The aircraft engine is a complex system that consists of a large number of integral components. When modeling the thermodynamic loss of a single component, it is ascribed with a loss parameter, such as an efficiency or a loss coefficient that relates to the type of operation of the said component. The performance of the aircraft engine is thus dependent on a large number of components' performance. Furthermore, the aircraft engine has weight and contributes to drag that must be compensated for by the engine. Using the conventional way to assess performance, it is impossible to compare one component's loss to another or to directly relate an individual component's loss to the overall loss.

The developed framework detailed in this thesis is able to relate the component performance directly to the overall loss, and thus, also enables direct comparison of the losses between the different components. Furthermore, the framework can also include the effect of weight and drag.

The developed framework is used to study various aircraft engines. In general, it can be said that the hot exhaust gases that leave the engine, the combustion process in itself, and the part of the kinetic energy in the exhaust that is not used to propel the aircraft forward, are the main sources of the overall loss. Therefore, this thesis also outlines different technologies aiming to address the aforementioned main loss contributors.



Rymd- och flygteknik



Strömningsmekanik och akustik


Hållbar utveckling



Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4316


Chalmers tekniska högskola

HB4 Hörsalsvägen 8, Göteborg

Opponent: Professor Guillermo Paniagua, School of Mechanical Engineering, Purdue University, United States of America

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