ResearchProject Area A
Subproject A6

Subproject A6 Mixing and Combustor Signature

Within the sub-project A6 the influence of defects on the functionality of aircraft engines is simulated and researched. One declared aim of the Collaborative Research Center is to detect possible engine failures by analysing the exhaust jet and to obtain information about the condition of the engine. Related to this issue is the question of the impact of the mixing on the signature of combustor defects and the detection limit. With the new approach of the complex diffusion mixing processes can be described.

MOTIVATION AND OBJECTIVES

Influence of a burner failure on the temperature distribution along the hot gas path

Defects in combustion chambers of aircraft engines might reduce the performance and represents an increasing stress of the turbine. The mixing is determined by turbulent diffusion processes. These processes are highly complex in the combustion chamber and turbine, which is due to the boundary conditions in the combustor and the flow channels between the turbine blades. A simplified approach will be developed for estimating the turbulent mixing together with the standard averaged RANS-modeling. The mixing process of a manipulated partial flow will be investigated in turbulent combustors of different complexity in experimental (e.g. laser diagnostics) and numerical (CFD) ways. The experimental set-ups offer the possibility to manipulate the combustion process concerning flow velocity, temperature and exhaust gas concentration in a defined way.

RESULTS

In the first funding period, it could be proved by numerical simulations that signatures of defects in combustor chambers are detectable in the exhaust jet. In the last period a simplified combustion chamber was developed to investigate defects and to determine the influence on the exhaust jet with different measurement techniques. In addition, CFD-models were tested and numerical calculations were conducted to simulate the flow and reaction processes. The simulated flow field was validated successfully by laser measurement techniques. These calculations allow both the investigation of further defects which cannot be implemented and experimentally evaluated and the intelligent associating of combustor errors and measured texture of the exhaust jet.

Impact of mixing on the signature due to turbulent diffusion (left) and complex geometry-dependent processes (right)

CURRENT RESEARCH AND OUTLOOK

In the further course of the current funding period the validated model will be applied to a real combustor of an aircraft engine. The intention is to describe the impact of the mixing on the signature without increasing the required computing effort for the simulation. In order to apply the model to the processes in the turbine, it will also be tested with the RANS simulations of subproject A3. The improved modeling will be compared with the results of the BOS measurement technique behind the engine. The effect of the complex mixing on the signatures of combustor defects also influences the pattern recognition methodology, which is required for automatic associating of combustor defects and the damage library. With a realistic estimation of the mixing processes, the smallest detectable defects can be determined. The calculation of the reactive processes in combustion chambers is also of interest for other aircraft engines and stationary gas turbines and enables corresponding transfer projects. This also applies to the methodology to describe the mixing of signatures.

Simulated temperature distribution within the combustion chamber of an aircraft engine with a reduced fuel mass flow at the middle burner

PUBLICATIONS

All publications of the Collaborative Research Centre

SUBPROJECT LEADER

Prof. Dr. Friedrich Dinkelacker
Address
Welfengarten 1A
30167 Hannover
Address
Welfengarten 1A
30167 Hannover

STAFF

M. Sc. Henrik von der Haar
Address
Welfengarten 1 A
30167 Hannover
Building
Room
209
Address
Welfengarten 1 A
30167 Hannover
Building
Room
209