bluuebunny/crossref_metadata_2025_split huggingface dataset:
Wall Temperature Measurements in a Full Scale Gas Turbine Combustor Test Rig With Fiber Coupled Phosphor Thermometry
Authors: Nau Patrick , Görs Simon , Arndt Christoph , Witzel Benjamin , Endres Torsten 
Published: January 2021

Abstract
Wall temperature measurements with fiber coupled online phosphor thermometry were, for the first time, successfully performed in a full scale H-class Siemens gas turbine combustor. Online wall temperatures were obtained during high-pressure combustion tests up to 8 bar at the Siemens CEC test facility. Since optical access to the combustion chamber with fibers being able to provide high laser energies is extremely challenging, we developed a custom-built measurement system, consisting of a water-cooled fiber optic probe and a mobile measurement container. A suitable combination of chemical binder and thermographic phosphor was identified for temperatures up to 1800 K on combustor walls coated with a thermal barrier coating (TBC). To our knowledge these are the first measurements reported with fiber coupled online phosphor thermometry in a full scale high-pressure gas turbine combustor. Details of the setup and the measurement procedures will be presented. The measured signals were influenced by strong background emissions, probably from CO2* chemiluminescence. Strategies for correcting background-emissions and data evaluation procedures are discussed. The presented measurement technique enables detailed study of combustor wall temperatures and using this information an optimization of the gas turbine cooling design.
Influence of Inlet Distortions on the Forced Vibration of a High Pressure Compressor Rig
Authors: Franz Falco , Kühhorn Arnold , Giersch Thomas , Figaschewsky Felix , Schrape Sven 
Published: January 2021

Abstract
This paper aims at getting a better understanding of the simulative prediction of low engine order excitations in axial compressors. The focus is on the influence of inlet distortions on the forced response of a 4.5-stage research compressor rig. The papers starts with a brief description of the rig. After that the numerical setups required to conduct aerodynamic damping and forced response analyses are presented. Experimental data obtained during a rig test campaign show a significant response of a fundamental mode of the rotor 2 blisk to a low engine order 4. This resonance is studied throughout the paper. A superposition effect of different low engine order 4 sources was observed when changing the clocking of the inlet distortion. The vibrational amplitudes are computed using a subset of nominal system modes model incorporating a measured mistuning distribution. Measured amplitude versus blade patterns are compared with those computed by the aeromechanical models. The observed superposition effect is a key finding and is leveraged to establish comparability of the results.
Exploring Applicability of Acoustic Heat Transfer Enhancement Across Various Perturbation Elements
Authors: Agarwal Tapish , Stratmann Maximilian , Julius Simon , Cukurel Beni 
Published: January 2021

Abstract
The requirements of improved heat transfer performance on turbine surfaces and internal cooling passages drive the research into exploring new methods for efficiency enhancements. Addition of ribbed structures inside the cooling ducts has proven to be most practical, which increases heat transfer from surfaces to fluid flow at the cost of some pressure loss. Many active and passive methods have been proposed for enhancing the heat transfer, where acoustic excitation has been recently shown to be an effective option. Moreover, the existing pressure fluctuations due to rotor-stator interactions can also be utilized as a source of excitation. However, the sensitivity of the phenomenon to various flow and geometric parameters has not been fully characterized.
The present study investigates various aspects of convective heat transfer enhancement and turbulent flow modulation caused by acoustic forcing on separating and reattaching flow over isolated rib obstacles. A parametric study is conducted; rib obstacles of various sizes and shapes (including rectangular, squared, triangular, semi-cylindrical, etc.) are installed in a low-speed, fully turbulent wind tunnel and measurements are taken at different velocities and excitation frequencies. Static pressure and spatially resolved surface temperature measurements are performed to quantify the ramifications of acoustic excitation on the wetted wall. Within the favorable Strouhal number range of 0.1–0.25, an optimum value of 0.16 is observed. It is shown that triangular ribs are more prone to acoustic heat transfer enhancement than rectangular or cylindrical perturbations. A linear correlation between static pressure recovery rate and acoustic heat transfer enhancement is observed, which is invariant to change in size/shape of the rib as well as flow and excitation parameters.
Experimental and Numerical Characterization of a Novel Natural Gas Low NOx Burner in Gas Turbine Realistic Environment
Authors: Cerutti Matteo , Nassini Pier Carlo , Pampaloni Daniele , Andreini Antonio 
Published: January 2021

Abstract
A fundamental milestone in the development of a low NOx burner technology is the demonstration of its capabilities in realistic environment. This is especially true for the novel burner subject of this paper, which has been extensively characterized throughout single burner scale experiments. An exhaustive description of the early development phases of the novel burner has been provided by authors in recently published works.
The most promising geometry was selected for the assessment in real combustor arrangement, consisting of a full-scale annular combustor test rig. This paper reports the main results of such an assessment. Pollutant emissions and pressure pulsations have been measured at gas turbine relevant operating conditions. Moreover, dedicated blow-out tests have been performed to obtain the extinction equivalence ratio at both ambient and pressurized conditions, as done during the past single burner rig campaign. Basically, an adequate set of data has been gathered, allowing a direct comparison between full-annular and reduced-scale tests.
A general alignment of behaviour has been observed, as both low NOx capability and blow-out characteristics of full-annular arrangement turned out to be substantially unchanged with respect to single burner. Nevertheless, some discrepancies in magnitude have been highlighted and discussed. Details have been given involving deeper numerical analysis by means of a dedicated model developed by the authors in previous works. Indeed, improvement to the model has been introduced in the context of this paper to overcome some limitations arisen in predicting emissions. Finally, a preliminary stability analysis has been carried out, with the aim to describe the onset of thermoacoustic instability tendency as observed in the full-annular tests.
A Methodology to Characterize Modal Damping in Vibrating Systems: Application to the Case of Gas Turbine Combustion Chambers
Authors: Amedei Andrea , Meli Enrico , Rindi Andrea , Pucci Egidio 
Published: January 2021

Abstract
The present paper proposes a methodology to characterize the modal damping ratio as a function of frequency in vibrating systems, with a focus on gas turbine combustion chambers. Proposed methodology correlates the modal damping ratio to the system modal eigenfrequencies, accurately considering the damping physical effects on the system dynamics and goes beyond the standard proportional damping hypothesis and similar techniques present in the literature.
The methodology has been compared under free-free conditions with standard damping ratio laws that can be found in the literature and which may lead sometimes to an overestimation of the real damping ratio values. Experimental data obtained through dedicated ping tests performed on two components of an industrial gas turbine annular combustion chamber have been used for the methodology validation: comparison between simulated and experimental results seems to be encouraging and the proposed methodology for modal damping ratio characterization turns out to be better, with respect to the standard ones, in reproducing not only the experimentally estimated damping law (as a function of the frequency), but also the typical Force Response Functions (FRFs) of the considered vibrating systems.
Finally, since the adopted procedure is numerically efficient and based only on low cost experimental techniques, it can be used for describing modal damping in vibrating systems since the early phases of the design, by increasing the design accuracy and reducing times and costs.
Prompt Atomization Mechanism of the Tangentially Injected Prefilming (TIP) LDI Injector
Authors: Wang Yuwei , Han Xiao , Lin Yuzhen 
Published: January 2021

Abstract
Lean direct injection (LDI) combustion is one of the promising low pollution combustion technologies. One challenge of implementing LDI combustion is to achieve quick fuel-atomizing and mixing with air. In this paper, the spray characteristics and the prompt atomization process of the tangentially injected prefilming (TIP) LDI injector are investigated by experiments; the energy transmission model suitable for the prompt atomization process and the semi-empirical estimation model of SMD for the conical liquid film are derived. All experiments were carried out under 20°C and atmospheric pressure by using kerosene as the fuel. Firstly, effects of We and ALR on the spray distribution and SMD were studied by Mie scattering and Malvern spraytec laser diffraction system respectively, which were carried out at the operating conditions of We varying from 664 to 2656 and ALR varying from 16.3 to 24.5. Results show that large We is beneficial to disperse the spray in primary zone downstream the swirler. Then, breakup regimes of liquid film and droplets evolution were characterized by a high-speed camera with a long-distance microscope (LDM). Breakup regimes show that the film is torn up by the fierce outer airstream immediately. The primary breakup process does not rely on the surface waves anymore, which conforms to the prompt atomization mechanism. Finally, the energy transmission of the conical liquid film during the whole atomization process was analyzed, from which the semi-empirical estimation model of SMD was derived. The calculated and the measured SMD have good consistency, which demonstrates the applicability of the prompt atomization energy transmission model on a conical liquid film.
The Multi-Phase Flow Test Facility “EMMA” to Investigate Local Heat Transfer Coefficients and Liquid Water Films at Wet Steam Conditions
Authors: Lapp Florian Felix , Hecker Simon , Schuster Sebastian , Brillert Dieter 
Published: January 2021

Abstract
Conventional power plants are obliged to compensate for the fluctuations in power generation, due to the rising amount of renewable energies, to ensure grid stability. Consequently, steam turbines are more frequently facing load variation and startup/shut-down cycles leading to an increase of thermal stress induced by phase change phenomena. The review of existing test facilities providing measurement data of heat transfer coefficients influenced by multiphase phenomena, such as surface wettability and dry-out, revealed the necessity for a new measurement application. This paper presents the design of the Experimental Multi-phase Measurement Application “EMMA” to generate the required conditions in combination with an academic turbine housing geometry. The performed investigations are focused on the local distribution of heat transfer coefficients (HTC) and the surface wettability affected by phase change phenomena. Two main film formation mechanisms can be observed, depending on the thermal gradient between the fluid and the wall. These are a) saturated/superheated steam in contact with a sub-cooled wall leading to film-wise/drop-wise condensation and b) primary condensed wet steam droplets depositing on a superheated wall, leading to evaporation. Both, the liquid film and the local heat transfer are measured simultaneously. An overview of applicable thickness measurement methods for transparent liquid films is given and the applied optical measurement system is further described. Moreover the HTC measurement methods are presented considering the occurring case of phase change.
Hybrid Numerical-Experimental Model Update Based on Correlation Approach for Turbine Components
Authors: Saeed Zeeshan , Firrone Christian Maria , Berruti Teresa Maria 
Published: January 2021

Abstract
Bladed-disks in turbo-machines experience high cycle fatigue failures due to high vibration amplitudes. Therefore, it is important to accurately predict their dynamic characteristics including the mechanical joints at blade-disk (root joint) or blade-blade (shroud) interfaces. These joints help in dampening the vibration amplitudes. Before the experimental identification of these joints, it is of paramount importance to accurately measure the interface degrees-of-freedom (DoF). However, they are largely inaccessible for the measurements. For this reason, expansion techniques are used in order to update the single components before their coupling. But the expansion can be affected adversely if the measurements are not properly correlated with the updated model or if they have significant errors.
Therefore, a frequency domain expansion method called System Equivalent Model Mixing (SEMM) is used to expand a limited set of measurements to a larger set of numerical DoF. Different measured models — termed the overlay models — are taken from an impact testing campaign of a blade and a disk and coupled to the numerical model according to the SEMM. The expanded models — termed the hybrid models — are then correlated with the validation channels in a round-robin way by means of Frequency Response Assurance Criteria (FRAC). The global correlations depict whether or not a measurement and the respective expansion is properly correlated. By this approach, the least correlated channels can be done away with from the measurements to have a better updated hybrid model.
The method is tested on both the structures (the blade and the disk) and it is successfully shown that removing the uncorrelated channels does improve the quality of the hybrid models.
A Combined Experimental and Numerical Characterization of the Flowfield and Heat Transfer Around a Multiperforated Plate With Compound Angle Injection
Authors: Laroche Emmanuel , Donjat David , Reulet Philippe 
Published: January 2021

Abstract
The aerodynamic and thermal behaviour of multiperforated zones in combustors is essential to the development of future combustion chambers. Detailed databases are therefore essential for the validation of RANS/LES solvers, but also regarding the derivation of heat transfer correlations used in 0D/1D in-house codes developed by engine manufacturers. In the framework of FP7 EU SOPRANO Program, the test-rig used in a previous study is modified to be compatible with anisothermal conditions. The plate studied is a 12:1 model with a 90° compound angle injection. A heating system is used to generate a moderate temperature gradient of about 20 K between the secondary hot flow and the main cold flow. The aerodynamic field is acquired by a PIV 2D-3C (Particle Image Velocimetry) system. The surface heat transfer coefficient is derived based on surface temperature distribution acquisitions. Several heating power levels are tested, which allows to evaluate the convective heat transfer coefficient and reference temperature through a linear regression. Measurements are conducted on both sides of the plate, which also gives access to those quantities on the injection/suction sides. From a numerical point of view, the configuration is studied using the unstructured ONERA in-house CEDRE solver. A systematic comparison is presented between the experimental and numerical database.
Effect of Geometric Uncertainty on a One Stage Transonic Compressor of an Industrial Gas Turbine
Authors: Venkatesh S. , Suzuki K. , Vahdati M. , Salles L. , Rendu Q. 
Published: January 2021

Abstract
The geometrical uncertainties can result in flow asymmetry around the annulus of compressor which in turn can detrimentally affect on the compressor stability and performance. Typically these uncertainties arise as a consequence of in-service degradation and/or manufacturing tolerance, both of which have been dealt with in this paper. The paper deals with effects of leading edge damage and tip gap on rotor blades. It was found that the chord-wise damage is more critical than radial damage.
It was found that a zigzag pattern of arranging the damaged rotor blades (i.e. most damaged blades between two least damaged blades) would give the best possible performance and stability when performing maintenance and overhauling while a sinusoidal pattern of arrangement had the worst performance and stability. This behaviour of zigzag arrangement of random damaged blades is consonant with the behaviour of zigzag arrangement in random tip gaps. It is also shown in this work that the level of damage has a bigger impact on the compressor performance and stability than the number of damaged blades.
Platform Centered Reduction: A Process Capturing the Essentials for Blade-Damper Coupled Optimization
Authors: Gastaldi Chiara , Gola Muzio M. 
Published: January 2021

Abstract
The purpose of this document is to continue along the line of research of the authors in the direction of developing an attractive tool for designers in the initial design phase of the damping of the turbomachinery blades. In particular, in order to guide their initial choice of a dry friction underplatform damper in the most appropriate way. The paper shows how, to this purpose, certain reasonable simplifications are introduced in the procedure and in the model, leaving the customary full high fidelity computations to the final design verification analysis. The key simplifications here considered are:
– the blade neck is modelled with Euler beam finite elements so to speed up the updating of its dimensions during the optimisation process;
– the contact forces exerted by the dampers on the two sides of the blade platform are represented by the resultant forces and moments applied to a reference point on the platform, associated to its displacements and rotations;
– as an improvement to the model proposed in the paper presented at Turbo Expo 2019, the airfoil is now obtained from a full 3D FE model after a component mode synthesis reduction; this choice is justified by the facts that the airfoil is by large the item with most complex shape and that during the coupled optimization of the damper the airfoil is considered to be of fixed shape.
It is shown that the process captures the essentials of the nonlinear dynamics of the blade-damper problem without sacrificing in any way the accuracy of the results.
This hybrid model is then employed in the process where the domains of optimal matching between the damper and the blade is searched for by exploring the influence of blade neck thickness (flexibility) and damper mass. Such a purposely simplified process allows a clear identification of relationships between relevant blade features and response with a focus on fatigue life. At the same time, it allows an assessment of the interplay between blade parameters and damper parameters in determining the modal features and the damping capabilities. It is shown how different matching solutions may be identified depending on the expected forcing level on the blade.
Sizing and Operation of a Hybrid Energy Plant Composed of Industrial Gas Turbines, Renewable Energy Systems and Energy Storage Technologies
Authors: Bahlawan Hilal , Gambarotta Agostino , Losi Enzo , Manservigi Lucrezia , Morini MIrko , Spina Pier Ruggero , Venturini Mauro 
Published: January 2021

Abstract
Hybrid energy plants, which include both fossil fuel technologies and renewable energy systems, can provide an important step towards a sustainable energy supply. In fact, the hybridization of renewable energy systems with gas turbines which are fed by fossil fuels allows an acceptable compromise, so that high fossil fuel efficiency and high share of renewables can be potentially achieved. Moreover, electrical and thermal energy storage systems increase the flexibility of the energy plant and effectively manage the variability of energy production and demand.
This paper investigates the optimal sizing of a hybrid energy plant which combines an industrial gas turbine, renewable energy systems and energy storage technologies. The considered renewable energy system is a photovoltaic system, while the energy storage technologies are electrical energy storage and thermal energy storage. Moreover, a compression chiller and a gas boiler are also considered. For this purpose, the load profiles of electricity, heating and cooling during a whole year are taken into account for the case study of the Campus of the University of Parma (Italy). The sizing optimization problem of the different technologies composing the hybrid energy plant is solved by using a genetic algorithm, with the goal of minimizing primary energy consumption. Moreover, different operation strategies are analyzed and compared so that plant operation is also optimized.
The results demonstrate that the optimal sizing of the hybrid energy plant, coupled with the optimized operation strategy, allows high average cogeneration efficiency (up to 84%), thus minimizing primary energy consumption.
Dynamic Stress Analysis of Exposed Pipes Subjected to Moving In-Line Inspection Tool
Authors: Mostaghimi Hamid , Hassani Mohsen , Yu Deli , Hugo Ron , Park Simon 
Published: January 2021

Abstract
In-line inspection is a non-destructive assessment method commonly used for defect assessment and monitoring of pipelines. The passage of an ILI tool through an excavated or exposed section of a pipe during an integrity assessment can excite vibrations and exert substantial forces, stress, and deflections on the pipe due to the weight and speed of the ILI tool. When the excitation frequency due to the ILI tool movement is close to the natural frequency of the overall structure, the dynamic stress generated within the pipe can be large enough to the extent that it imposes integrity concern on the line. This research aims to study effects of the ILI tool passage through floating and partially supported pipes under a variety of boundary and loading conditions. A finite element method is used to model the pipe with moving ILI tool. The model is developed based on Timoshenko beam theory with planar degrees-of-freedom and the differential equations of motion are solved numerically to predict displacement, strain, stress, and frequency responses of the pipe. The model is further validated using a lab-scale experimental setup. The comparison of the simulation to experimental results show how the proposed model is capable of predicting pipe dynamics, effectively.