Figure 2: Numerical fluid-structure interaction simulation of a gas turbine piezoadaptive compressor blade
Project:TurbIn - Substantial Efficiency Increase in Gas Turbines through Direct Use of Coupled Unsteady Combustion and Flow Dynamics
Funding: DFG - German Research Foundation / CRC 1029
Project duration: 01.04.2012 - 31.03.2021
Project description: A significant increase of the efficiency of gas turbines is the objective of CRC 1029 and shall be achieved by changing the combustion concept towards an approximately constant volume combustion. Two concepts have been investigated up to now. While the pulsed detonation combustion bases on an extremely fast combustion triggered by shock waves, it also causes large pressure fluctuations. These are largely reduced by the alternative concept of a shockless explosion combustion, where a specific layering of the fuel and the utilization of acoustic phenomena lead to a homogeneous auto-ignition of the whole combustion tube. The third period of CRC 1029 will additionally include the rotating detonation combustion. Due to pressure waves traveling in circumferential direction at very high frequencies, this concept seems to be very promising for implementation in gas turbines as well. In contrast to conventional gas turbine processes, all described combustion concepts feature periodically unsteady pressure waves and will thus have a significant impact on the operating conditions of the turbomachinery components within the gas turbine. Methods and experiments have been investigated to effectively reduce the pressure pulsation at the interfaces between compressor, combustion chamber and turbine. Furthermore, sufficient cooling of the first turbine stage as well as flow stability at the compressor exit must be safeguarded and have thus been further focus areas of CRC 1029. One objective was to reduce the additional effort to a minimum to protect the overall efficiency gain of the whole gas turbine. Within the third period, the developed measures shall be driven towards a higher degree of maturity within relevant gas turbine conditions. For the same reason, the holistic assessment of the engine, which was solely based on well-developed thermodynamic methods so far will now be expanded to look at structural mechanics’ aspects as well. Within the third period, the achieved results of the projects shall coalesce in the setup of a demonstrator platform. It shall serve to develop process control strategies in different load regimes as well as to derive representative boundary conditions for the experiments with dedicated stand-alone rigs of compressor and turbine.
Subproject B01: Active flow control of stator cascades at periodically-transient boundary conditions The project aims to transfer the results of the previous funding periods for active flow control in compressors to realistic engine conditions. For this purpose, experimental investigations are carried out on two high-speed test rigs in order to develop an actuator system, which can be used in the relevant Mach number regime of up to Ma∞= 0.6 upstream of the compressor cascade. By means of numerical flow simulations, fluidic actuators are designed for application in highly compressible flows with the aim of adapting the actuator characteristics to turbomachine-like flow conditions. Experimental measurements and adaptations of the fluidic actuators are carried out on the linear cascade. Subsequently, the effect of the whole actuator system for flow control with an adjustable throttle valve will be used in a full-scale annular test rig under representative periodically unsteady flow conditions.
Subproject B02:Impact of rotor-stator-interaction with periodic choke by adaptive blade control The focus of the subproject is the targeted influencing of the unsteady flow processes between the rotor and stator grids of a compressor via adaptive blade geometries to control the flow effects under highly fluctuating boundary conditions. In this context, the blades are modified with controllable folding and camber mechanisms and their effect on the flow fields is investigated. In this context, the targeted influence on the flow is an important prerequisite for stable and efficient compressor operation, especially in connection with the planned pressure-increasing pulsating combustion.
 Werder, Tobias; Kletschke, Lukas; Liebich, Robert: "Experimental Investigations of Active Flow Control Using a Piezo Adaptive Blade in a Compressor Cascade Under Periodic Boundary Conditions with High Strouhal-Number". Papers Contributed to the Conference Active Flow and Combustion Control 2021, September 28-29, 2021, Berlin, Germany, p. 358. http://doi.org/10.1007/978-3-030-90727-3_19
 Werder, Tobias; Liebich, Robert; Neuhäuser, Karl; Behnsen, Clara; King, Rudibert: "Active Flow Control Utilizing an Adaptive Blade Geometry and an Extremum Seeking Algorithm at Periodically Transient Boundary Conditions". ASME Vol. 143, p. 6. 02.2021.https://doi.org/10.1115/1.4049787
 Motta, V., Malzacher, L., Bicalho Civinelli de Almeida, V., Phan, T. D., Liebich, R., Peitsch, D., and Quaranta, G.: "A Physically Consistent Reduced Order Model for Plasma Aeroelastic Control on Compressor Blades". ASME. J. Eng. Gas Turbines Power. September 2019; 141(9): 091001. https://doi.org/10.1115/1.4043545.
 Civinelli de Almeida, Victor Bicalho; Malzacher, Leonie; Liebich, Robert; Motta, Valentina; Phan, Tien Dat; Peitsch, Dieter: "Aeroelastic control of compressor blades in transonic flow using plasma actuators". 15th International Symposium on Unsteady Aerodynamics, Aeroacoustics & Aeroelasticity of Turbomachines ISUAAAT 15 University of Oxford, UK 24. - 27.09.2018.
 Neumann, P.; Motta, Valentina; Malzacher, Leonie; Phan, Tien Dat; Liebich, Robert; Peitsch, Dieter; Quaranta, Giuseppe: "Reduced order modeling for plasma aeroelastic control of airfoils in cascade: Dynamic mode decomposition". IUTAM Symposium on Critical flow dynamics involving moving/deformable structures with design applications. Santorini, Greece 18. - 22.06.2018.
 Phan, Tien Dat; Springer, Patrick; Liebich, Robert: "Numerical Investigation of an Elastomer-Piezo-Adaptive Blade for Active Flow Control of a Nonsteady Flow Field Using Fluid–Structure Interaction Simulations". ASME Journal of Turbomachinery, Vol. 139, Issue 92017. https://doi.org/10.1115/1.4036107.
 Hammer, Steffen; Peter, Julija; Thamsen, Paul Uwe; Phan, Tien Dat; Liebich, Robert: "Adaptive Blade Systems for Increased Operating Range of a Turbomachine". ASME/JSME/KSME 2015 Joint Fluids Engineering Conference. Seoul, South Korea 26. - 31.07.2015.https://doi.org/10.1115/AJKFluids2015-33762.