bluuebunny/crossref_metadata_2025_split huggingface dataset:
Large Eddy Simulations on Fan Shaped Film Cooling Hole With Various Inlet Turbulence Generation Methods
Authors: Kang Young Seok , Jun Sangook , Rhee Dong-Ho 
Published: January 2021

Abstract
Large eddy simulations on well-known 7-7-7 fan shaped cooling hole have been carried out. Film cooling methods are generally applied to high pressure turbine, of which flow condition is extremely turbulent because high pressure turbines are generally located downstream combustor in gas turbines. However, different to RANS simulations, implementing turbulence at the main flow inlet is not simple in LES. For this reason, several numerical techniques have been devised to give turbulence information at the inlet boundary condition in LES. In this study, rectangular turbulator was located in front of the cooling hole to generate turbulent boundary flow in the main flow. Another method used in this study is transient table method to simulate turbulent flow at the main flow inlet. Without turbulent velocity components in approaching flow, laterally discharged cooling flow touches wall while it forms a vortex structure. Then high film cooling effectiveness region around the cooling hole appears. In the meanwhile, when approaching flow is turbulent, the laterally discharged cooling flow no more forms vortex structure and dissipated to the main flow and resultant high effectiveness region disappears. Both turbulence generation methods showed that turbulent intensity of the main flow affects effective range of the cooling flow and resultant film cooling effectiveness distributions. Also high turbulence intensity of the main flow stimulates early break down of the vortex structure coming out of the cooling hole and its dissipation to the main flow. It means high turbulent intensity restricts film cooling flow coverage. Another lesson from the study is that vortex generated from the cooling hole, its development and dissipation to the main flow, have an important role to understand film cooling effectiveness distributions around the cooling hole.
Dynamics of Effusion Cooling Fluid in a Pressurized Swirl Combustor Flow
Authors: Chandh Aravind , Kazbekov Askar , Zhang Angie , Adhikari Subodh , Wu David , Emerson Ben , Rezvani Reza , Proscia William , Lieuwen Tim , Steinberg Adam 
Published: January 2021

Abstract
This paper presents measurements of 10 kHz acetone planar laser induced fluorescence (PLIF) to study the behavior of effusion cooling fluid injected into a non-reacting gas turbine combustor flow at elevated pressure. This study was performed as part of a larger effort to understand potential interactions of the swirling flame with the cooling air. The combustor — which was representative of a rich-burn/quick-quench/lean-burn (RQL) configuration — consisted of a swirl nozzle, quench jets, and a modular liner that could be fitted with various effusion cooling panels and optical access windows. Primary air was seeded with acetone, and passed through the swirl nozzle. Unseeded secondary air was passed on the outside of the liner, entering the combustion chamber through the quench jets and effusion panels. The PLIF laser sheet was arranged parallel to the effusion panel at various offset distances to visualize the mixing between the core flow and effusion jets. The PLIF images were analyzed with a POD-based methodology to de-noise the images and identify patterns in the effusion jet characteristics. The results show that high blowing ratios produce individual effusion jets rather than a single, coalesced film. The effusion jets are highly unsteady, interacting strongly with the turbulent flow from the swirl nozzle and dilution jets. Furthermore, the average trajectories of effusion jets are non-uniform across the panel and are shaped by upstream features in the combustor, namely swirl and dilution jets.
Integration of an Open Source Blade Geometry Generator Using a Physics Based Parameterization With the Engineering Sketch Pad
Authors: Sharma Mayank , Dannenhoffer John F. , Holder Justin , Turner Mark G. 
Published: January 2021

Abstract
This paper reviews an in-house turbomachinery blade generation system which integrates easily in an MDAO driven design process while providing the designer with a flexible and parsimonious parameterization scheme along with insights gained from interaction with 3D geometry. T-Blade3 is an open source 3D parametric blade geometry generator which uses a novel parameterization scheme based on the specification of the second derivative of the mean-line and a continuous modified NACA four digit thickness distribution as B-spline control points. The second derivative parameterization ensures curvature and slope of curvature continuity on the airfoil surface which leads to a smooth surface pressure distribution. Use of spanwise B-spline control points ensures the creation of smooth 3D geometries and keeps the overall parameterization space small. The Engineering Sketch Pad (ESP) is an open-source interactive web-enabled solid modeling system based on WebViewer and OpenCSM. The open-source nature of OpenCSM allows the use of user-defined primitives to create solid blade models using T-Blade3 geometries. OpenCSM also allows the computation of the sensitivity of surface points to design parameters using a combination of analytical derivatives and finite differences. Thus, the T-Blade3/ESP combinations allows a designer to interact with parametrically generated geometries and make improvements to the design using sensitivity information and a gradient based optimization loop. Furthermore, ESP enables the addition of flends (similar to fillets) to solid blade models. The resulting blades with applied centrifugal and pressure loads are then analyzed with a commercial FEM structural solver to get factor of safety relative to yield strength, natural frequencies and mode shapes.
Numerical Investigation of Dump Diffuser Combustor Performance at Uniform and Non-Uniform Inlet Conditions
Authors: Wang Heyu , Luo Kai Hong 
Published: January 2021

Abstract
A numerical investigation has been conducted for an axisymmetric dump diffuser combustor, which is a simplified geometry of a typical lean-burn combustor in a modern civil aero-engine gas turbine. The aerodynamic performance of the combustor is analyzed with an emphasis on two common performance parameters: static pressure recovery and total pressure loss. The former is essential in maintaining high-pressure air flow across the liner, whereas the latter involves the specific fuel consumption of the aero-engine. At first, the effects of geometrical parameters of the dump diffuser combustor are investigated. A high diffuser angle seems to be detrimental to both static pressure recovery and total pressure loss. On the other hand, a high dump gap ratio is beneficial from the aerodynamic performance point of view. However, all these desired characteristics are subject to mechanical constraints and their implications for specific consumption. Optimum values of those parameters should exist for a given desired aerodynamics performance. The majority of previous researches, including the first part of this study, have been carried out with uniform inlet conditions due to a typical independent design cycle of each component. The effects of compressor exit conditions are usually not considered in the early stage design process. In the second part of this study, various inlet conditions representing a more realistic compressor exit condition such as inlet symmetrical and asymmetrical boundary layer thickness are investigated. The performance of an asymmetrical configuration with a thin boundary layer thickness near the outer annulus is almost comparable to that of its uniform counterpart. Findings of this study provide useful input for combustor designers to improve the combustor’s performance based on the compressor exit conditions.
Development of an Integrated Procedure for Combustor Aero-Thermal Preliminary Design
Authors: Elmi Carlo Alberto , Agnolio Fabio , Ferraro Roberto , Menard Anne , Reese Hauke , Andreini Antonio 
Published: January 2021

Abstract
In the development of an aero-engine combustor, the definition of a preliminary design is a practice in which know-how, product experience and design rules are focal in deriving a configuration able to meet the functional requirements. Several configurations, and hence multiple geometries resulting in different behaviours, are iteratively analysed in this phase to extensively explore the design space. In this context, an automated procedure ranging from preliminary design to life estimation is necessary and crucial. A framework in which the tools employed in the design workflow are integrated and the low-added-value tasks are automated can allow the reduction of time per analysis within the loop and the enhancement of the procedure’s robustness.
In this paper will be presented the Combustor Design System Integration (DSI), a methodology aimed at easing and streamlining the design process of aero-engine combustors. To do this, digitization has been taken as the common thread for developing a data-centric approach. The logic behind the procedure will be reported, to focus then on the aero-thermal preliminary design. The procedure, for this phase, is composed of three main integrated components: a CAD generation system, which collects all the geometries for creating an exportable 3D model, a 1D thermal solver for the positioning and sizing of the aero feature on liners (i.e. cooling, dilution...) and a CFD environment with automated pre/post processing operations for reacting-flow analysis.
The aim of this work is to contextualize the DSI approach in the combustor design process and to provide a first description of the methodology designed and developed in GE Avio. For that purpose, a straight-through configuration — the lean combustor NEWAC developed in the homonymous EU project — will be exploited as a test case. The development of the procedure is still in progress, so a validation through test cell data comparison, as well as highly-resolved CFD results, will be the subject for future papers.
Progress on Forcing Pulsations for Acoustic, Thermoacoustic or Flow Control Purpose in a Pressurised Vessel by Means of a Siren
Authors: Giuliani Fabrice , Stütz Markus , Paulitsch Nina , Andracher Lukas 
Published: January 2021

Abstract
A siren is a robust fast-valve that generates effective flow pulsations and powerful noise levels under combustor field conditions. Its principle relies on a sonic jet sheared periodically by a cogged wheel rotating at a given speed. Developed for experiments in combustion stability, it offers an alternative to loudspeakers when the use of these is made difficult because of aggressive flow conditions (e.g. elevated conditions of pressure and temperature, presence of impurities in the gas). While the siren was designed for laboratory applications, its technology is a promising candidate for effective flow control on gas turbine fleets. By scanning through a given frequency range, one detects the acoustic resonance of specific parts of the combustor assembly and identifies a zone of combustion instability during a sensitivity analysis where the flame is exposed to calibrated perturbations. Regarding control applications, it can act out of phase for damping purposes in the low-frequency domain (phase control), or transfer the acoustic energy to a higher and less harmful sub-harmonic (modal control). Since a chocked nozzle is involved, the siren’s actuation is decoupled from the flow condition downstream, which is convenient for control. Following-up to previous works where a siren model was introduced with the capacity to vary the amplitude of pulsation independently from the frequency [GT2011-45071], this paper describes into details new features as follows. First, the performance of the apparatus was improved to visit frequencies in the 0–6 kHz range so that the operation is extended to frequencies met by precessing vortex cores in a burner or tangential instabilities in an annular combustor. Next, the discharge configuration is tested and validated as an alternative to the conventional blow-down operation with the siren placed upstream of the pressurised test cell. There, the siren is placed downstream of the test cell, deriving a small part of the pressurised air in the plenum. Finally, a new calibration procedure for fast pressure probes and accelerometers is presented and tested. A multi-modal excitation is introduced where more than one frequency peak is being produced and where the excited frequencies create a kind of a chord. In conclusion the siren is recommended as an effective flow controller, and as a broadband and powerful calibrator.
Design and Optimization of Non-Supercritical CO2 Thermal Power Cycle for “P2H2P” Energy Storage System
Authors: Burian Ondrej , Skoda Radek 
Published: January 2021

Abstract
Most of the current research and development of CO2 cycles for power to heat - heat to power (P2H2P) energy storage systems are focused on applications of supercritical CO2 cycles. However, this work is focused on alternative application of CO2 power cycle with standard (i.e., non-supercritical) cycle and modified industrial turboexpanders as main working machines. Thermal Cycle for power storage system with thermal energy accumulator for energy storage and non-supercritical CO2 power cycle for backward production of electricity is described in this paper. The CO2 cycle is compared with Nitrogen cycle with same parameters as well. Initially, the thermal accumulator design, option of accumulation media (molten salts or liquid metals), and its parameters are described. The main part of the paper is focused on non-supercritical CO2 power cycles. Possible configurations of cycle, design aspects of main parts of cycle, possibilities of efficiency improvement are discussed; such as regeneration or intercooling. Finally, advantages and disadvantages of this CO2 and N2 cycle are discussed and compared. The concluding result of this paper is a very similar efficiency of the two working fluids at the selected parameters.
Adjoint-Based Optimization of a Modern Jet-Engine Fan Blade
Authors: Giugno Andrea , Shahpar Shahrokh , Traverso Alberto 
Published: January 2021

Abstract
A Multi-point Approximation Method (MAM) coupled with adjoint is presented to increase the efficiency of a modern jet-engine fan blade. The study performed makes use of Rolls-Royce in-house suite of codes and its discrete adjoint capability. The adjoint gradient is used along with MAM to create a Design Of Experiment to enhance the optimization process. A generalized Free-Form Deformation (FFD) technique is used to parametrize the geometry, creating a design space of 180 parameters. The resulting optimum blade at design conditions is then evaluated at off-design conditions to produce the characteristic curve, which is compared with real test data. Finally, a preliminary Active Design Subspace (ADS) representing the fan efficiency is created to evaluate the robustness of the objective function in respect to the most significant design parameters. The ADS allows to collapse a large design space of the order of hundreds parameters to the few most important variables, measuring their contribution. This map is valuable in many respects to the fan designers and manufacture engineers to identify any ridges where the performance may deteriorate rapidly, hence a more robust part of the design space can easily be visualized and identified.
Experiments With a Rotor-Hybrid Gas Bearing System Undergoing Maneuver Loads From its Base Support
Authors: San Andrés Luis , Rodríguez Bryan 
Published: January 2021

Abstract
Gas bearings enable microturbomachinery (MTM) with a large power to weight ratio, low part count and nearly frictionless motion, thus resulting in systems operating over extended maintenance intervals and with improved fuel efficiency. Envisioned oil-free vehicle transportation systems implementing gas bearings range from small size gas turbines, to unmanned aerial vehicles, to turbochargers (TC), and more to come. In these vehicles, base or support transient displacements transmit forces exciting the rotor-bearing system; hence, the need to characterize system integrity under stringent operating conditions. This paper reports experiments demonstrating the ability of a hybrid gas bearing-rotor system to withstand maneuver actions that suddenly remove the ground support. The test rig consists of a rigid motor-rotor, supported on tilting pad hybrid gas bearings supplied with pressurized air. The rotor is housed in a thick steel casing that is attached to a rigid base plate. The whole test rig, hangs from a crane; two steel cables connect to one side of the base and a nylon webbing attaches to the other side of the base. The other end of the webbing ties to a release mechanism, which when released, frees one side of the rig base. Suddenly, the whole test rig rotates and displaces downwards while the tensions in the taut cables rapidly increase and pull the test rig as it swings back and forth. The crane support enables two release maneuvers; one turns the rig ∼90°, and the other flips it 180°, both events occurring while the rotor spins at 70 krpm (surface speed 105 m/s). The measured rotor displacements relative to the casing demonstrate a momentary increase in motion amplitude, up to ∼1.15 mm since the bearings also displace, along with a maximum casing deceleration of ∼7 g when the cables stop the rig fall. The measurements show the rotor response is free of sub synchronous whirl frequencies that could evidence a rotor dynamic instability. Very low frequency motions denote the swing frequency of the hanging rig and jerk motions from the crane lifting and bouncing when the rig is at its lowest vertical position. In one instance, power to the motor unexpectedly interrupted and the rotor underwent an unplanned shaft speed coastdown. In spite of the large displacements recorded, the rotor survived both events. It continues to operate to this day. The experiments demonstrate that the hybrid gas bearing system could withstand large amplitude rotor excursions. The measurements provide a novel method for testing gas bearings, as the induced excitations are multidirectional, while the test rig encounters a short period of free falling, followed by a quick deceleration with large forces. A simple kinetics model of the test rig drop produces peak decelerations similar in magnitude to those measured.
Analysis of the Design Bounds in Performance Limits for Industrial Axial Flow Fans
Authors: Cravero Carlo , Milanese Gabriele 
Published: January 2021

Abstract
The design of an industrial axial flow fan can take great advantage from the knowledge of performance limits and favourable design choices determined from its specific fluid-dynamic characteristics. As for other turbomachinery types, this fact is generally experienced through the entire design flow-path, from the preliminary design phase to the final optimization. Correlations, data and charts available from literature as well as proprietary database, exploited with many techniques (including machine learning) are resources in widespread use for this purpose. Despite the fluid dynamics of axial flow fans can be considered a well-known topic, nevertheless some specific points (e.g. the maximum achievable total-to-static efficiency) can be the subject of discussions, misunderstanding or bad design choices. The present work addresses this problem in two parts. In the first part a simple 1D model is built, for fans with and without stator, from classical theory of axial fans for pressure rise coefficient, head coefficient, flow angles and diffusion efficiency. The most relevant quantities (e.g. total-to-total efficiency, total-to-static efficiency), obtained with the 1D model, are plotted on hill charts as a function of the non-dimensional pressure rise and flow coefficient. This tool provides information that can be used for preliminary design evaluations, to understand and exploit the impact of the main design choices on the basic flow characteristics and the related performance. In the second part of the work a numerical investigation is presented on the main 3D flow characteristics that are observed to limit, both in CFD simulations and experimental tests, the performance of industrial axial fans at high-pressure rise and low-to-medium flow coefficients. Simulations results highlighted that local critical swirl ratios exist for the hub and the tip regions which, when exceeded, lead with different flow topology changes to a strong performance degradation.
Thermal Profiling of Automotive Turbochargers in Durability Tests
Authors: Pilgrim Christopher C. , Ehrhard Jan , Schinnerl Mario , Araguás-Rodríguez Silvia , Peral David , Straka Marc-Sebastian , Genschmar Mike , Karagiannopoulos Solon , Pacheco-Gutierrez Salvador , Feist Jörg P. 
Published: January 2021

Abstract
A major portion of the development of an automotive powertrain system is devoted to robustness and durability testing to ascertain the viability of the design. For turbochargers, thermo-mechanical fatigue is often considered as life limiting failure mechanism for the turbine section, therefore, these tests involve repeated and continuous cycling of the turbocharger for hundreds of hours. Thermocouples are used to monitor the temperature during the test, however, they only provide information at the location to which they are attached, are practically challenging to apply to all areas of interest and are prone to fail due to the thermal cycling throughout the test. As a result, there may be very limited temperature data at the end of the test. If a failure occurred in the system during the testing, the lack of temperature data can inhibit the understanding of the cause. Further testing may be required and delay product release, which add significant expense to the product development.
The Thermal History Coatings (THC) developed by Sensor Coating Systems can offer a new and unique solution to provide complimentary temperature information for this purpose. THCs are applied to the surface of a component and, when heated, the coating permanently changes according to the maximum temperature of exposure. A laser-based instrumentation system is then used to measure the coating or paint, and through calibration, the maximum temperature profile of the surface can be recorded. Although this technique is relatively new, it has been used in several turbomachinery, and other applications to capture the spatial temperature distribution of critical components. However, the turbocharger durability test presents new challenges for the technique. It has not been tested in this type of application and the extended and repeated cycling operation can test the durability of the coating and will influence the response of the coating, hence, the temperature measurements. The internal surfaces of the turbocharger will also be exposed to the exhaust gases of the combustion process.
In this paper, the capability of the THC for this application was investigated. For the first time, the effect of cyclic operation on the THC is reported. The measurement capability was demonstrated on two turbine housings tested on a gas stand, one for a single cycle, another for 10 cycles. The results show that the surface temperature profile of the two turbine housings can be accurately recorded and the results are validated against the installed thermocouples. The demonstration indicates that the THC can be used to acquire accurate and detailed spatial temperature distributions, which significantly enhance the information from thermocouples alone. This information can be used to improve the interpretation of the durability test and hence accelerate new product release.