ResearchProject Area A
Subproject A3

Subproject A3 Exhaust Jet Analysis

The project comprises the development of an automated recognition of defective parts in the hot gas path of aircraft engines through a non-contact analysis of density distribution in the exhaust jet with the help of the Background-Oriented Schlieren (BOS) method.

MOTIVATION AND OBJECTIVES

Exhaust jet analysis with the BOS-method

MOTIVATION AND OBJECTIVES

Currently, aircraft engines have to be first dismounted before defective parts can be identified. The complexity and duration of repairs and therefore the downtime of the engine currently cannot be accurately estimated, because the existing defects can be found only during ongoing regeneration process. Consequently, the regeneration process is not only time- and cost-intensive, but also has serious uncertainties in the planning. The methodology, which is being developed in the subproject A3, allows to evaluate the condition of an aircraft engine without its dismounting. The idea of the methodology is that defective parts in the hot gas path (HGP, engine components after combustion chamber) have an influence on the local density distribution in the flow in form of density irregularities that extend throughout the HGP up to the exhaust jet. The irregularities in the exhaust jet can be detected with the help of the Background-Oriented Schlieren method that allows to identify, which engine defect was the cause of it. It therefore allows both a quick check of the engines for faulty parts and appropriate maintenance, and improved planning of repair procedures due to early damage identification.

RESULTS

In the first two funding periods of the SFB it was possible to show numerically that defective parts have an influence on the density distribution in the exhaust jet, and that they can be detected by tomographic BOS measurements. With the help of pattern recognition algorithms is was also possible to analyze the reconstructed density distributions and automatically identify the defects. Alongside with these numerical investigations, it was shown at the helicopter engine of TFD that the application of the tomographic BOS measurements on engines is generally possible. Moreover, tomographic BOS measurements at the model of a combustion chamber showed that it is also possible to detect the defects in combustion chambers with the help of density distributions in the exhaust jet. Even small deviations of the burner performance of a circular combustion chamber could be detected via further development of the tomographic analysis algorithms.  

Density distribution in the exhaust jet of a swirl burner array for the reference case (left) and a complete shutdown of one burner (right).

CURRENT RESEARCH AND OUTLOOK

Finally, the developed methodology should be validated at the real aircraft engine during the current third funding period of the SFB. To this end, predefined defects will be applied to the engine and the exhaust jet will be reconstructed with the tomographic BOS method during two measurement campaigns. The influence of the defects on the exhaust jet will be investigated by a comparison of the measurements with a reference state of the engine (without defects). Additionally, this influence will be estimated in a numerical model that will be validated with the help of measurement results. After this validation, it is possible to predict numerically the influence of other defects on the exhaust jet and to build a data bank with different damage cases.  An engine in an unknown state can be then optically measured and the measurement results with the help of pattern recognition algorithms can be compared with the data bank. Therefore, the defects can be detected contact-free without the dismounting of the engine.


PUBLICATIONS

  • Hartmann U.; Seume, J. R. (2016) Combining ART and FBP for improved fidelity of tomographic BOSMeas. Sci. Technol. 27 (9), S. 097001
    DOI: 10.1088/0957-0233/27/9/097001
  • Hartmann, U.; Hennecke, C.; Dinkelacker, F.; Seume, J. R. (2016) Automatic Detection of Defects in a Swirl Burner Array Through an Exhaust Jet Pattern AnalysisIn: J. Eng. Gas Turbines Power 139 (3)
    DOI: 10.1115/1.4034449
  • Adamczuk, R.R.; Luehrmann, J.; Seume, J.R. (2014) Methodology for evaluating hot gas path defects in an exhaust jetAerospace Science and Technology 39 (Vol. 39), S. 120–127
    DOI: 10.1016/j.ast.2014.08.011
  • Adamczuk, R.; Seume, J. R. (2012) Time Resolved Full-Annulus Computations of a Turbine with Inhomogeneous Inlet ConditionsInternational Journal of Gas Turbine, Propulsion and Power Systems 4,2, S. 01–07
All publications of the Collaborative Research Centre

SUBPROJECT LEADER

Prof. Dr.-Ing. Jörg Seume
Address
Appelstraße 9
30167 Hannover
Address
Appelstraße 9
30167 Hannover

STAFF

M. Sc. Vladislav Pak
Address
Appelstr. 9
30167 Hannover
Address
Appelstr. 9
30167 Hannover