bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mandrel-Free Hot-Spinning of 17-4 PH Truncated Cone
Authors: Ikawa Ken , Imamura Yoshihide , Motoyama Kojiro , Iwasaki Hayato , Hirakawa Takeo 
Published: November 2019

Abstract
Forming experiments were carried out using 17-4 PH plates with 490 mm dia. × 5 mm thick and 7 mm thick. A truncated cone with 30 degrees wall angle was formed at 600 °C and 850 °C by using mandrel-free hot-spinning. The material properties and shape accuracy of the formed product were investigated with as-formed products and products subjected to a solution and aging treatment.
It was found that the mandrel-free hot-spinning is able to form 17-4 PH plate into truncated cone. From the viewpoint of the forming accuracy and material properties of formed product, mandrel-free hot-spinning can be applied to 17-4 PH plate by forming at a temperature above 850 °C followed by an appropriate solution and aging treatment. In addition, it was confirmed that the deformation behavior of the formed product shows the same tendency as the deformation behavior of the Ti-6Al-4V alloy plate.
CFD Simulation of Air Ingestion in a Squeeze Film Damper
Authors: Yan Wang , Xuesong Li , Yuhong Li 
Published: November 2019

Abstract
Squeeze film damper (SFD) is widely adopted in the high performance rotor-bearing systems to eliminate rotor vibration and improve stability. Experiments show that the air ingestion from the open end would have notable impact on the SFD performance. Multiphase Computational Fluid Dynamics (CFD) calculation on the air ingestion in the SFD is conducted in this work. Results are validated with the experimental data to prove the capability of the multiphase CFD on predicting the air ingestion. Air and oil flow in the SFD are analyzed in details. By comparing the CFD results with and without air ingestion, the effect of air ingestion is revealed. Results show that CFD is capable of predicting the air-oil flow in the SFD. The maximum air region is located in the vicinity of the largest bearing clearance region rather than the low pressure zone. And air ingestion in the largest bearing clearance region counteracts the hydrodynamic pressure effect in the vicinity.
TURBODYNA: Centrifugal/Centripetal Turbomachinery Dynamic Simulator and its Application on a Mixed Flow Turbine
Authors: Yang Bijie , Martinez-Botas Ricardo 
Published: November 2019

Abstract
1D modelling is crucial for turbomachinery unsteady performance prediction and system response assessment. The purpose of the paper is to describe a newly developed 1D modelling (TURBODYNA) for turbomachinery. Different from classic 1D modelling, in TURBODYNA, rotor has been meshed and its unsteadiness due to flow field time scale is considered. Instead of direct using of performances maps, source terms are added in Euler equation set to simulate the rotor. By comparing 1D modelling with 3D CFD results, It shows that rotor unsteadiness is indispensable for a better prediction. In addition, different variables response to pulse differently. In the rotor, mass flow is close to quasi-steady while entropy is significantly unsteady. TURBODYNA can capture these features correctly and provide an accurate prediction on pressure wave transportation.
Load Independent Losses of an Aeroengine Epicyclic Power Gear Train: Numerical Investigation
Authors: Bianchini Cosimo , Da Soghe Riccardo , Giannini Lorenzo , Fondelli Tommaso , Massini Daniele , Facchini Bruno , D’Errico Jacopo 
Published: November 2019

Abstract
The development of Ultra-High Bypass Ratio (up to 20) engines with the aim of improving the propulsive efficiency, introduces new challenges for the transmission system in terms of heat management and power losses, since the amount of power transferred through the gearbox is greatly increased. In this respect the accurate estimate of losses at the various flow regimes realized during a typical aeroengine mission within a Power Gear Box (PGB) is essential for the correct design and operation of the engine itself.
This paper proposes a computational methodology to estimate all fluid-dynamic (load-independent) losses, which become a major source of dissipation at the high rotational speeds typical of aeroengines, developing within an epicyclic PGB. The overall procedure is based on the superposition principle and approaches the three fluid-dynamic losses, namely injection, windage and meshing losses, with different numerical techniques.
The simulations of windage effects, which consider the actual PGB geometry including the carrier disk, the lubricant spray-bar and the external casing, are based on steady-state computations. In order to introduce such simplification, a scaling procedure that avoids interference of the stationary and rotating interfaces was implemented following the outcomes of a previous analysis.
The computation of meshing losses employs a fully unsteady dynamic mesh approach and considers a portion of the meshing gears only. Both the sun-planet and planet-ring meshing were considered showing that the latter introduces a much lower level of losses.
Finally the injection losses are calculated considering the oil jet momentum variation with simplified methods based on 0D modelling.
The proposed procedure, based on the superposition principle and applied to a planetary power gear train, is tested against experimental results described in a previous paper focused on a meshing gear pair.
Prediction of Reynolds Number Effects on Low-Pressure Turbines Using a High-Order ILES Method
Authors: Bolinches-Gisbert Marc , Robles David Cadrecha , Corral Roque , Gisbert Fernando 
Published: November 2019

Abstract
A comprehensive comparison between Implicit Large Eddy Simulations (ILES) and experimental results of a modern highlift low-pressure turbine airfoil has been carried out for an array of Reynolds numbers (Re). Experimental data were obtained in a low-speed linear cascade at the Polithecnic University of Madrid using hot-wire anemometry and LDV. The numerical code is fourth order accurate, both in time and space. The spatial discretization of the compressible Navier-Stokes equations is based on a high-order Flux Reconstruction approach while a fourth order Runge-Kutta method is used to march in time the simulations. The losses, pressure coefficient distributions, and boundary layer and wake velocity profiles have been compared for an array of realistic Reynolds numbers. Moreover, boundary layer and wake velocity fluctuations are compared for the first time with experimental results. It is concluded that the accuracy of the numerical results is comparable to that of the experiments, especially for integral quantities such as the losses or exit angle. Turbulent fluctuations in the suction side boundary layer and the wakes are well predicted also. The elapsed time of the is about 140 hours on 40 Graphics Processor Units. The numerical tool is integrated within an industrial design system and reuses pre- and post-processing tools previously developed for another kind of applications. The trend of the losses with the Reynolds number has a sub-critical regime, where the losses scale with Re−1, and a supercrital regime, where the losses scale with Re−1/2. This trend can be seen both, in the simulations and the experiments.
Gas Turbine Combined Cycle Flexibility: A Dynamic Model for Compressor Intake Conditioning Through a Heat-Pump
Authors: Rossi Iacopo , Piantelli Luca , Traverso Alberto 
Published: November 2019

Abstract
The flexibility of power plants is a critical feature in energy production environments nowadays, due to the high share of non-dispatchable renewables. This fact dramatically increases the number of daily startups and load variations of power plants, pushing the current technologies to operate out of their optimal range. Furthermore, ambient conditions significantly influence the actual plant performance, creating deviations against the energy sold during the day-ahead and reducing the profit margins for the operators. A solution to reduce the impact of unpredicted ambient conditions, and to increase the flexibility margins of existing combined cycles, is represented by the possibility of dynamically controlling the temperature at compressor intake. At present, cooling down the compressor intake is a common practice to govern combined cycle performance in hot regions such as the Middle East and Africa, while heating up the compressor intake is commonly adopted to reduce the Minimum Environmental Load (MEL). However, such applications involve relatively slow regulation of air intake, mainly coping with extreme operating conditions. The use of continuously varying, at a relatively quick pace, the air temperature at compressor intake, to mitigate ambient condition fluctuations and to cope with electrical market requirements, involves proper modeling of the combined cycle dynamic behavior, including the short-term and long-term impacts of intake air temperature variations. This work presents a dynamic modeling framework for the whole combined cycle applied to one of IREN Energia’s Combined Cycle Units. The paper encloses the model validation against field data of the target power plant. The validated model is then used to show the potential in flexibility augmentation of properly adjusting the compressor intake temperature during operation.
A Supercritical CO2 Combined Power and Liquefaction Cycle
Authors: Beck Griffin , Ransom David , Hoopes Kevin 
Published: November 2019

Abstract
Natural gas production has increased dramatically in recent years due to advances in horizontal drilling and hydraulic fracturing techniques. There are still challenges that must be addressed by industry to better utilize these abundant natural gas resources. For example, due to the cost and complexity with piping installations from remote well sites to processing facilities (should they exist), natural gas is often flared at the site whereas the liquid hydrocarbons are stored in holding tanks.
For the natural gas that is recovered and processed, there are currently economic benefits to exporting the gas to international markets, provided that the gas can be liquefied and shipped. While the number of liquefaction facilities has increased in recent years, additional liquefaction plants are needed.
This paper introduces a novel liquefaction cycle that utilizes a supercritical carbon dioxide (sCO2) power cycle to provide power and initial stages of refrigeration to a natural gas liquefaction cycle. The liquefaction cycle uses a flow of CO2 extracted from the power cycle as well as natural gas to provide several stages of refrigeration capable of liquefying the process stream. The combined sCO2 power and liquefaction cycle is described in detail and initial cycle analyses are presented. The cycle performance is compared to small-scale natural gas liquefaction cycles and is shown to provide comparable performance to the reviewed cycles. Due to the compact nature of the sCO2 power cycle equipment, the sCO2 liquefaction cycle described herein can provide small, modular liquefaction plants that can be employed at individual well sites to liquefy and store the natural gas as opposed to flaring the gas.
High Momentum Jet Flames at Elevated Pressure: Part C — Statistical Distribution of Thermochemical States Obtained From Laser-Raman-Measurements
Authors: Ax Holger , Lammel Oliver , Lückerath Rainer , Severin Michael 
Published: November 2019

Abstract
A detailed investigation on flame structures and stabilization mechanisms of confined high momentum jet flames by 1D-laser Raman measurements is presented. The flames were operated with natural gas (NG) at gas turbine relevant conditions in an optically accessible high pressure test rig. The generic burner represents a full scale single nozzle of a high temperature FLOX® gas turbine combustor including a pilot stage.
1D-laser Raman measurements were performed on both an unpiloted and a piloted flame and evaluated on a single shot basis revealing the thermochemical states from unburned inflow conditions to burned hot gas in terms of average and statistical values of the major species concentrations, the mixture fraction and the temperature. The results are supported by complementary measurement techniques that have been previously conducted and presented in the connected papers part A and B [1,2], such as OH*-chemiluminescence, planar laser-induced fluorescence (PLIF) and particle image velocimetry (PIV), that combine to a big picture of the flame structures and help to interpret the results.
The results show a distinct difference in the flame stabilization mechanism between the unpiloted and the piloted case. The former is apparently driven by strong mixing of fresh unburned gas and recirculated hot burned gas that eventually causes autoignition. The piloted flame is stabilized by the pilot stage followed by turbulent flame propagation. The findings help to understand the underlying combustion mechanisms and to further develop gas turbine burners following the FLOX® concept. The combined results of all measurement techniques that have been applied to these two flames thus form a unique and comprehensive data set for the validation of numerical simulation models.
Efficiency Measurement Approach for a Hydrogen Oxyfuel Combustor
Authors: Tanneberger Tom , Schimek Sebastian , Paschereit Christian Oliver , Stathopoulos Panagiotis 
Published: November 2019

Abstract
The increasing generation share of renewable energy sources in the power sector raises the demand for fast and flexible large-scale storage technologies. Steam generation via stoichiometric combustion of H2 and O2 within a steam cycle is a promising way to back convert both gases. These gases can be generated by electrolysis that utilizes excess renewable energy. At the same time, this technology could provide balancing and spinning network reserves. A crucial parameter of this approach is combustion efficiency, since residual H2 or O2 can damage downstream components of the steam cycle. The current paper investigates the combustion efficiency of a H2/O2 burner under steam diluted conditions. The combustion efficiency measurement is very challenging in this case, as the combustor products consist mostly of pure steam and cannot be dried for conventional gas analysis. This is solved by an in-situ measurement method to quantify the combustion efficiency. This approach and relevant challenges are presented along with results regarding the combustion efficiency of a model H2/O2 combustor. Additionally, a design configuration study of the combustor is conducted by varying the swirl intensity and examining jet as well as swirl-stabilized flames. The initial results of the project suggest that steam-diluted H2 oxyfuel combustion with efficiencies close to 100% is possible.
Control Technology Needs for Electrified Aircraft Propulsion Systems
Authors: Simon Donald L. , Connolly Joseph W. , Culley Dennis E. 
Published: November 2019

Abstract
Electrified aircraft propulsion (EAP) systems hold potential for the reduction of aircraft fuel burn, emissions, and noise. Currently, NASA and other organizations are actively working to identify and mature technologies necessary to bring EAP designs to reality. This paper specifically focuses on the envisioned control technology challenges associated with EAP designs that include gas turbine technology. Topics discussed include analytical tools for the dynamic modeling and analysis of EAP systems, and control design strategies at the propulsion and component levels. This includes integrated supervisory control facilitating the coordinated operation of turbine and electrical components, control strategies that seek to minimize fuel consumption and lessen the challenges associated with thermal management, and dynamic control to ensure engine operability during system transients. These dynamic control strategies include innovative control approaches that either extract or supply power to engine shafts dependent upon operating phase, which may improve performance and reduced gas turbine engine weight. Finally, a discussion of control architecture design considerations to help alleviate the propulsion/aircraft integration and certification challenges associated with EAP systems is provided.
Experimental Analysis of an Additively Manufactured Cooled Ultra Compact Combustor Vane
Authors: Rathsack Tylor C. , Bohan Brian T. , Polanka Marc D. , Rutledge James L. 
Published: November 2019

Abstract
The Ultra Compact Combustor (UCC) offers a means to reduce overall combustor size. Unlike traditional axial flow combustors, the UCC utilizes an outboard circumferential cavity as the primary combustion zone. This combustor design enables the implementation of a Hybrid Guide Vane (HGV), located radially inboard of the circumferential cavity, to be positioned with the leading edge axially upstream of the hot combustion gases. Previous Computational Fluid Dynamics (CFD) efforts determined the viability of a passive cooling scheme where cooler compressor air was drawn into an opening at the stagnation region of the HGV and used for both internal and film-cooling of the vane. The present study investigates the performance of five cooled HGV configurations each having a unique combination of film-cooling, internal passage area, and internal passage geometry. The effectiveness of film-cooling holes to both protect the hardware and alter the flow path of the hot gases exiting the combustor cavity were evaluated for a range of core flow conditions. Further, the impact of a trailing edge slot to maintain an appropriate coolant flow rate through the HGV was evaluated. Results confirmed the efficacy of HGV with passive air ingestion. A solid structure located inside the cooled vanes affected the internal coolant mass flow and pressure rise and thus the overall cooling effectiveness. Further, optimal blowing ratios were demonstrated to buffer hot streaks in the freestream path resulting in a more uniform radial temperature distribution.
Rig Testing of the Operability of a Transonic Compressor Blade of an Industrial Gas Turbine
Authors: Kang Hyunsu , Ahn Sungjong , Hwang Kyusic , Bock Justin , Kang Jeongseek , Montgomery Matthew 
Published: November 2019

Abstract
This paper describes the flow and vibrations measured in a 1.5-stage transonic research compressor tested at the Notre Dame Turbomachinery Laboratory. The compressor is a sub-scale version of a large-scale industrial gas turbine. The experiment measured the compressor performance and investigated the operability issues of stall and flow-induced blade vibrations due to buffet and flutter. The buffet was investigated at full-speed with fully-closed inlet guide vanes; the full-speed, no-load condition of gas turbines used for power generation. The flutter was investigated at part-speed conditions with partially closed guide vanes; the part-power condition where stall flutter typically occurs for aero-engines. At both of these conditions the blades operate with high incidence and moderate velocity, which can result in flow-induced vibrations.
Aero-elastic simulations were performed to predict the flutter boundary. The flutter analysis predicted positive aerodynamic damping near the operating line, and a decrease in aerodynamic damping as the stall boundary was approached. No flutter was observed in the stable operating range of the compressor.
The experimental campaign used blade tip timing to measure the vibrations and unsteady pressure transducers above the compressor blade. These two types of data were correlated to better understand the drivers of vibration. The paper describes the behavior of the aerodynamic drivers of buffet and flutter and the resulting vibration.
Multipoint Optimization of an Axial Turbine Cascade Using a Hybrid Algorithm
Authors: Châtel Arnaud , Verstraete Tom , Coussement Grégory 
Published: November 2019

Abstract
This paper presents a constrained multipoint optimization of the LS89 turbine cascade. The objective of the optimization consists in minimizing the entropy losses generated inside the cascade over a predefined operating range. The operating range is bounded by two operating points respectively characterized by a downstream isentropic Mach number of 0.9 and 1.01. During the optimization, two aerodynamic constraints are imposed in order to conserve the same performance as the original cascade. The first constraint is established on the outlet flow angle in order to achieve at least the same flow turning as the LS89 turbine. The second constraint limits the mass-flow passing through the optimized cascade. The optimization is performed using a hybrid algorithm which combines efficiently a classical evolutionary algorithm with a gradient-based method. The hybridization process between both methods is based on the Lamarckian approach which consists in incorporating directly the gradient method inside the loop of the evolutionary algorithm. In this methodology, the evolutionary method allows to globally explore the overall design space while the gradient-based method locally improves certain designs located in the most promising regions of the search space. First, the better performance of the proposed hybrid method compared to the performance of a classical evolutionary algorithm is demonstrated on two benchmark problems. Then, the methodology is applied on a turbomachinery application in order to minimize the losses in the linear LS89 cascade.
The optimization process allows to find a new blade profile which reduces the entropy losses over the entire operating range by at least 9.5 %. Finally, the comparison of the flows computed in the baseline and in the optimized cascades demonstrates that the reduction of the losses is due to a decrease of the entropy generated downstream the trailing edges and within the passages between the optimized blades.
Aerodynamic Impact of Manufacturing Variation on a Nonaxisymmetric Multi-Passage Turbine Stage With Adjoint CFD
Authors: Liefke Alexander , Marciniak Vincent , Backhaus Jan , Frey Christian , Gottschalk Hanno , Janoske Uwe 
Published: November 2019

Abstract
Turbomachinery blade design is based on an axisymmetric model assuming identical blades in the circumferential direction. The blade manufacturing process, however, has a finite accuracy leading to surface imperfections and therefore non-identical blades. This leads to a variation in each passage cross area effecting the aerodynamic performance of the turbine.
The simulation of multiple 3D CFD blade passages, nevertheless, is still computational expensive. However, if the effect of nonaxisymmetric blades is small enough to be approximated as linear, the adjoint method is an inexpensive alternative, which can be used in an industrial context. A set of 102 turbine vanes is used to model the manufacturing variations and assess the aerodynamic impact of up to eight nonaxisymmetric blade passages of a transonic high pressure turbine stage.
It is shown that the modeled blade passage results superimpose linearly. Therefore, the aerodynamic impact of surface imperfections can be evaluated by superpositioning the singlepassage results, which are generated by an adjoint computation.