Engines and, thus, the compressor suffer operational, particlebased wear during operation depending on ambient conditions and particle size. Fouling describes the deposition of small particles on the blade surfaces leading to an increased blade thickness, surface roughness, and changed geometry. In experiments, the effect of fouling in the compressor is evaluated. Rough stator vanes are distributed equally spaced around the circumference or clustered within a stator row. The worn vanes are coated with a randomly distributed surface structure of hemispheres representing fouled vanes. The roughness parameters of the coating are based on measurements from a CFM-56 engine. The results show a better integral flow field for a non-uniform distribution. Losses in adjacent passages of the rough vanes are visible in wake flow measurements. Therefore, one-third of coated vanes, equally spaced around the circumference, are responsible for almost two-thirds of the efficiency losses of an entire rough stator row.

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The ability to efficiently optimise the charging system as part of the complete powertrain for a given duty is attracting significant research interest. A hybrid meanline model integrating Artificial Neural Networks as surrogate models for loss and blockage prediction has shown great potential in wide-range radial turbine performance prediction, demonstrating enhanced accuracy compared to traditional approaches. However, the configuration of surrogate models employed in the hybrid meanline modelling approach has not been studied thoroughly considering the wide range of geometrical variables and the dimensionality of the problem. This paper presents an investigation into a hybrid meanline model with regard to the choice of the surrogate model algorithm and the corresponding impact of the training database size. By optimizing the surrogate model hyperparameters via Bayesian Optimization, the effect of the hyperparameters on the performance of the surrogate models has been isolated. Various hybrid meanline models with different surrogate models were tested on unseen radial turbine geometries, and a comparison of the predicted efficiency is presented.

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The structural mechanical properties of blades in turbomachinery depend on the operating speed. In addition to effects such as stress stiffening and spin softening, the rotational speed influences the nonlinear contact properties in shroud-coupled turbine blades. A change in operating point consequently leads to changes in natural frequencies, vibration modes and effective damping. For the design of new turbine blades, the correct modeling of all combined speed-variable properties is necessary to protect the blades against high cycle fatigue failures at any operating point. A nonlinear computational model with a variable-speed formulation of the structural properties is developed and the dynamics of a medium-pressure turbine blading with shroud coupling is analyzed at several operating points. In a rotational test rig, the disk and blade assembly is excited with higher-harmonic excitation force components at different rotational speeds. The comparison of the amplitude responses shows the influence of the rotational speed on the damping and the resonant frequency and confirms the validity of the developed computational model.

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Modern civil turbofan aero-engines are faced with the challenge of noise control in a shorter nacelle and a larger bypass ratio fan design. Accordingly, the concept of soft vanes, in which fan outlet guide vanes (OGV) are implemented with permeable surfaces, is proposed to further reduce the rotor-stator interaction noise in future aero-engines. A three-dimensional cascade model is used to study the noise reduction of perforations on OGVs under practical situations as an application of soft vanes. The effects of spanwise coupling of the unsteady loading are studied and comparisons are made between a fully coupled model and a decoupled situation. The noise reduction effects of a perforated-plate based soft vane design under practical background mean flow at different operating conditions are then estimated using an in-house impedance model that accounts for the tangential mean flow and other practical factors.

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Renewable power generation capacities are mostly subject to inherent fluctuations. To maintain the security of supply in a regenerative-dominated energy system, flexible components must be increasingly implemented to balance the residual load. Among other options, gas turbines are eligible for this grid-serving task. However, fuel conversion in gas-based power generation technologies is inherently linked to emissions. This study investigates the impact of hydrogen deployment in single-cycle gas turbine power plants on the emission behavior and the corresponding emission footprint. The emission formation in different operational regimes is quantified by linking part load emission characteristics for different volumetric hydrogen admixing rates and time-resolved load profiles emphasizing startups, part load operation, and transient load changes. The results show that the emission species associated with incomplete combustion, i.e., CO, CH2O and CH4, significantly increase when operating the gas turbine in lower part load. CO2, NOx, and particulate matter (PM) emissions can not be assigned to a specific load condition. Due to enhanced chemical conversion rates, hydrogen admixing leads to a greater reduction of carbon-containing pollutants than the simple reduction of carbon atoms would suggest. In contrast, NOx emissions increase with hydrogen admixing dominantly via the thermal pathway. On the one hand, the environmental impact analysis shows that the impact of greenhouse gas emissions is dominated by CO2 emissions and therefore decreases with hydrogen admixing. On the other hand, the damage categories associated with human toxicity and photochemical ozone formation are dominated by NOx emissions and, therefore, increase with hydrogen admixing. The value of the damage category related to respiratory inorganics remains almost constant because the effects of PM reduction and NOx increase cancel each other out.

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Over the last five decades of the LNG industry, there has been a significant evolution in the drivers used to power the refrigeration compressors, spanning a wide range of solutions including steam turbines (ST), heavy duty or aeroderivative gas turbines (GT), electric motors, and their combinations [1]. The trend is currently driven by the need to reduce greenhouse gas emissions. A viable solution to reduce the CO2e/tonne LNG produced of LNG liquefaction plants with GT drivers is to utilize bottoming power cycle(s) (e.g., Steam Rankine Cycle or Organic Rankine Cycle) to recover the waste heat energy from the GT exhaust gases. Other options include a combination of hybrid drives (e.g., GT and ST, or GT and motor) for the refrigeration compressors. This paper is intended to describe opportunities, challenges, and design options for decarbonization of LNG liquefaction plants by focusing on gas turbine drivers of refrigeration compressors. It describes different design options for reducing carbon emissions in both brownfield and greenfield LNG liquefaction plants. Also covered are different design options for CO2 compression systems in LNG liquefaction plants, and transcritical compression pathways.

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The present study focuses on the influence of the trailing edge shape and on the development of coherent structures in the transonic flow of a turbine blade passage. Experiments were performed in the High-speed Cascade Wind Tunnel of the University of the Bundeswehr Munich on a high pressure turbine linear cascade. Enginerelevant flow conditions are examined at a constant exit Reynolds number of Re2th = 1,200,000 and a range of exit Mach numbers from Ma2th= 0.80 to 1.10. The aerodynamic characteristics of the highly unsteady flow is qualitatively investigated using a five hole wedge probe and Particle Image Velocimetry (PIV). By means of a Proper Orthogonal Decomposition (POD) analysis, dominant flow structures are extracted. The near wake flow and shear layer dynamics as well as the evaluation of the wake downstream of two trailing edge designs are examined. The results show performance benefits due to the mitigation of coherent structures for exit Mach numbers below Ma2th= 1.00 for the profiled trailing edge geometry. For higher exit Mach numbers the round trailing edge has a performance advantage as the strength of the main shock increases and seems to play a dominate role on the integral losses.

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By integrating piezoceramic Macro-Fiber-Composite (MFC) actuators into the blading of a fan rotor, a simultaneous morphing of the blade twist and turning can be achieved. While operating under off-design flow conditions the piezoceramic actuation allows to reduce flow incidence and deviation. With the overall goal to increase engine off-design efficiency, while maintaining a sufficient surge margin, this research aims to investigate the influence of blade reference shape variations on the morphing potential of a scaled fan rotor. An aerodynamic design methodology including a streamline curvature calculation is therefore coupled with structural morphing simulations. To quantify the impact of reference design variations on the blade’s deformability a Design of Experiment is conducted, resulting in the investigation of different axial compressor designs, ranging from high hub-to-tip ratio compressor rotors to scaled Ultra-High-Bypass-Ratio (UHBR) fan blading. Finally, a UHBR fan design for a test rig application is selected and its morphing behavior is further investigated through quasi 3D (Q3D) simulations for representative tip section designs.

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expected to increase in the long run. At the same time, however, there is an urgent need to reduce the emissions of carbon dioxide. Numerous researchers and companies are proposing advanced technologies globally. In our laboratory, research about all turboelectric has been conducted but it revealed a stringent demand for electrical components. Therefore, the objective of this research is to advance this research and find the feasible solution. The research about Partial Turboelectric (PTeDP) was conducted. By operating with less peak power during takeoff, the weight of electrical components such as motors and generators, which are proportional to the peak power, was reduced. PTeDP turned out to have a potential to reduce 1% to 2% Mission Fuel Burn compared to Turbofan.

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In this paper, a hydrogen fuel cell-based propulsion system for regional and future mid-range aircraft is investigated. The main focus herein lies on the exploration of the operating range of the cathode gas supply system of the fuel cell stack. Subsequently, resulting constraints that limit the design space of the entire propulsion system are shown. Investigations are carried out using the on-design thermodynamic cycle calculation module of the in-house software ASTOR (AircraftEngine Simulation for Transient Operation Research). It includes a fuel cell model which facilitates conservation of mass and energy along the cathode side of the fuel cell system, as well as the specic constraints of the fuel cell stack due to its operating conditions. The second objective of this study is to determine suitable design points for the cathode air supply system which will serve as the starting point for detailed design of turbo components. Optimum fuel cell operating conditions are identied throughout relevant operating points at constant stoichiometry. Furthermore, contradictory requirements of the air supply system in terms of compressor mass ow and pressure ratio are identied. Finally, the off-design performance is estimated in order to derive statements about the coverage of the operating range depending on the choice of the design point. The top-of-climb operating point may be chosen as the design point in order to cover most operating points. At the same time, high altitude operation with a constant-geometry system appears only feasible at unrealistically high stoichiometic ratios or with additional measures such as bleed valves downstream of the compressor.

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