Aerodynamic design framework for low-pressure compression systems
Doktorsavhandling, 2018

Aircraft engine manufacturers strive to improve current state of the art designs through continuous development efforts. By improving existing designs and exploring new alternatives, the goal is to reduce the fuel consumption - a topic of high relevance due to the remarkable growth rate of air traffc. To achieve a low fuel consumption, turbofan engines should operate at a high overall pressure ratio which is commonly achieved by an axial compressor. An axial compressor consists of a set of consecutive stages, each consisting of a rotating and stationary blade row. While a compressor should operate with a high pressure ratio, it should not operate too close to its stability limit where surge can occur. If surge occur in the compressor, the compressor blades will be subject to large transient forces and the ow may even reverse direction. The main focus of this thesis is the further development of an aerodynamic design framework for low-pressure systems, where an appropriate level of modeling is selected and compressor stages are optimized with respect to effciency and stability. Different approaches are used to evaluate stability of a compressor stage and it is concluded that the static pressure rise capability of the stage is an appropriate measure to use for ranking designs in an optimization. As a part of this thesis, all three stages of a three-stage compressor are optimized using steady state RANS calculations, and the performance of the three-stage compressor is evaluated as an assembly. The possibility of replacing blade geometries to improve part- or design speed stability of the three-stage compressor is shown. Other aspects which may penalize efficiency are investigated, namely the in uence of surface roughness and manufacturing variations on performance. The in uence of surface roughness on optimal stage designs is assessed by optimizing compressor blades with and without taking surface roughness into account. The impact of manufacturing variations on performance at a design point is investigated by utilizing measurements of a manufactured compressor blisk.

manufacturing variations

optimization

stage matching

tip clearance

validation

Turbomachinery

CFD

surface roughness

compressor

HA2
Opponent: Heinz-Peter Schiffer, Technische Universität Darmstadt, Germany

Författare

Marcus Lejon

Chalmers, Mekanik och maritima vetenskaper, Strömningslära

Lejon, M., Mårtensson, H., Andersson, N., Ellbrant, L. The Impact of Manufacturing Variations on Performance of a Transonic Axial Compressor Rotor,

Multidisciplinary Design of a Three Stage High Speed Booster

ASME Turbo Expo 2017: Turbine Technical Conference and Exposition,; (2017)

Paper i proceeding

On Improving the Surge Margin of a Tip-Critical Axial Compressor Rotor

ASME Turbo Expo 2017: Turbine Technical Conference and Exposition,; (2017)

Paper i proceeding

The Surge Margin of an Axial Compressor: Estimations from Steady State Simulations

ISABE International Society for Air Breathing Engines,; (2017)p. 1-13

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

Optimization of Robust Transonic Compressor Blades

ASME Turbo Expo 2016: Turbine Technical Conference and Exposition,; Vol. 2C(2016)

Paper i proceeding

Simulation of Tip-Clearance Effects in a Transonic Compressor

ASME Turbo Expo 2015: Turbine Technical Conference and Exposition,; (2015)

Paper i proceeding

CFD Optimization of a Transonic Compressor Stage with a Large Tip Gap

ISABE International Society for Air Breathing Engines,; (2015)p. 1-11

Konferensbidrag (offentliggjort, men ej förlagsutgivet)

The current growth rate of air travel (number of kilometers traveled multiplied by number of passengers) results in the air traffic being doubled every 15 years. This is a remarkable growth rate that highlights the importance of efficiency improvements and weight reductions in aviation to reduce fuel consumption and minimize the environmental impact.

To achieve a low fuel consumption, modern turbofan engines operate at high pressure ratios achieved in part by the low-pressure system, consisting of the fan and an axial compressor. An axial compressor consists of a set of consecutive stages, each consisting of a rotating and stationary blade row. While a compressor should operate with a high pressure ratio, it should not operate too close to its stability limit where surge can occur. If surge occur in the compressor, the blades will be subject to large transient forces and the flow may even reverse direction. This work has focused on improving a design framework for designing blades in a low-pressure compression system with a high efficiency and stability. A number of compressor stages and a fan blade are considered as part of the present work, where an appropriate level of modeling complexity is determined and performance is estimated from computational fluid dynamics (CFD) calculations. Criteria that can be used to rank compressor stages in terms of stability in an optimization are investigated, and a conclusion is presented regarding an appropriate measure.

Furthermore, the impact of geometric variations from manufacturing on performance is studied, a topic which is growing in popularity. If too much variability is allowed, it can have an adverse impact on efficiency and may even be a cause for concern from a safety perspective. However, if the allowed variability is set too strict, variations which are not detrimental to performance may need to be corrected at a high cost.

Ämneskategorier

Produktionsteknik, arbetsvetenskap och ergonomi

Rymd- och flygteknik

Farkostteknik

Drivkrafter

Hållbar utveckling

Styrkeområden

Transport

Energi

Infrastruktur

C3SE (Chalmers Centre for Computational Science and Engineering)

ISBN

978-91-7597-759-1

Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 4440

Utgivare

Chalmers tekniska högskola

HA2

Opponent: Heinz-Peter Schiffer, Technische Universität Darmstadt, Germany

Mer information

Senast uppdaterat

2018-06-11