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D01: Holisitc evaluation and improvement of a gas turbine with a periodic pressure-gain combustion

Principal investigator:
Prof. Dr.-Ing. Dieter Peitsch ()
Prof. Dr. Panagiotis Stathopoulos )

Scientist: Tim Rähse ()
Tel:   (030) 314 29379

Scientist: Nicolai Neumann ()
Tel:  (030) 314 29055

Summary

 

The periodic and transient character of pressure gain, almost isochoric combustion in gas turbine processes leads to highly transient boundary conditions for all subcomponents of the system. The resulting interactions must be assessed in terms of their significance for the overall engine in order to be able to make a statement about the intended efficiency gain and the reliable operating behaviour. This holistic view is the content of this subproject. In terms of this approach, the aim of the subproject is to enable a detailed energetic and exergetic analysis of a dynamic gas turbine process with pressure gain combustion under consideration of the effects of transient and gas-dynamic effects on the characteristic operating parameters of the individual components.

 

 

1st Funding period 2016 - 2020

Development of a simulation tool in cooperation with subproject A03 for thermodynamic process calculation.

The new software builds on the programme developed by TP A03 in the first phase. This program is able to simulate the gas dynamics during pressure gain combustion and is used to model the corresponding combustion chamber of the two combustion processes investigated: Pulse Detonation Combustion (PDC) and Shockless Explosion Combustion (SEC). The turbomachines were simulated by implementing source terms into the existing code and will allow transient simulation of the entire engine as soon as the coupling with the combustion chamber has been completed. In order to correctly estimate the potential for pressure gain combustion in the overall gas turbine system, the losses associated with unsteady effects must also be taken into account. This includes losses in the turbomachinery due to transient boundary conditions but also the additional compressor power required in the secondary air system to ensure a supply of cooling air. The losses of the turbomachinery are first accounted for by generic characteristics, and in the course of the second phase will be directly calculated by the mean line method, which has also been developed. This enables the efficiency of the transient turbomachinery to be determined. In addition, the secondary air system is modelled and the required compressor power is determined. Both reduce the overall efficiency of the gas turbine, but cannot be neglected for a potential estimate. Finally, the knowledge gained is used for the concept development of a demonstrator.

Analysis of the thermodynamic cycles

The thermodynamic cycle processes corresponding to the PDC and SEC combustion technologies were analysed and evaluated using combustion simulation results. Both stationary and quasi-stationary 0D calculations were made. In order to consolidate the basic understanding, parameter studies were carried out at different compressor pressure ratios and turbine inlet temperatures. In addition, cycle process optimizations were also carried out to identify the design of an efficiency-optimized gas turbine with pressure gain combustion.

Instationary exergy analysis

An analysis method was developed to investigate the exergetic efficiency in the combustion chamber. This was applied in a first step to the detonation of the PDC and the results are expected to be published in the second half of 2019. Furthermore, both the SEC and the processes in the plena will be investigated. Publication of the results is also planned for 2019 and early 2020.

Modelling of the secondary air system

First, a simplified secondary air system was used for the thermodynamic investigations. This consisted of a secondary air path connecting the compressor outlet with the turbine. The required pressure increase is produced by an additional compressor, which is also driven by the main shaft. The studies conclude that this compressor could consume up to 5% of the shaft power.

A detailed calculation of a secondary air network model is planned for 2019.  In addition to turbine blade temperatures, hot gas ingestion is also monitored.  Overall, this study shows how the SAS has to be modified, in order to be used in a gas turbine with pressure gain combustion.  

Publications

Neumann N., Woelki D., Peitsch D.,  A comparison of steady-state models for pressure gain combustion in gas turbine performance simulation, in GPPS-BJ-2019-0198.

N. Neumann, D. Peitsch, Introduction and Validation of a Mean Line Solver for Present and Future Turbomachines, 24th ISABE Conference, International Symposium on Air Breathing Engines, Canberra, Australia, Sep 23-27 2019, ISABE-2019-24441

Rähse, T. S., Stathopoulos, P., Arnold,F., Schäppel, J.S., King R. On the influence of fuel stratification and its control onThe efficiency of the shockless explosion combustion cycle. J. Eng. Gas Turbines Power 141,1 (2018).

Zusatzinformationen / Extras

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Auxiliary Functions

Speaker

Prof. Dr.-Ing. Dieter Peitsch

Managing director

Steffi Stehr
Room ER 102

Office

Steffi Stehr
sec. ER 2-1
Room 107
Hardenbergstr. 36a
10623 Berlin
+49 (30) 314 23110