bluuebunny/crossref_metadata_2025_split huggingface dataset:
Towards a Detailed Liquid Fuel Injection Model for Gas Turbine Combustor CFD
Authors: Wang L. , Ozogul H. , Kaushik T. , Bhat A. , Rida S. 
Published: January 2021

Abstract
Fuel injection modeling plays an important role in Computational Fluid Dynamics (CFD) based combustor design and performance analysis. The specification of initial fuel spray size, velocity, and location strongly affects the subsequent fuel air mixing and combustion processes. Current common practice of introducing fuel spray in combustor CFD relies on either experimental correlations built from spray data measured at locations further away from injector exit or simplified theoretical models that have limited applications. This often leads to large uncertainties in spray initial conditions and inconsistencies in combustor model performance. Although much progress has been made in multiphase simulation of primary atomization, involving a two-phase flow solver in combustor CFD to resolve liquid fuel injection processes is still not feasible in the foreseeable future. Standalone fuel injection simulations, however, can provide valuable information on initial spray distributions required for accurate fuel injection modeling in combustor CFD. In this paper the approach of using a standalone or separate detailed fuel injection simulation to provide initial spray boundary condition for combustor CFD is demonstrated in a Liquid Jet In Cross Flow (LJICF) configuration. The primary atomization (PA) of the LJICF is simulated using a Volume of Fluid (VOF) solver on a fine mesh, and the blobs and ligaments from the PA simulation are collected and transferred to another separate simulation of spray using a Lagrangian particle tracking solver on a coarser mesh. The results from the Lagrangian simulation are compared with experimental data as well as the results from a conventional fuel injection model. The differences from the comparisons are discussed to reveal the challenges and new modeling needs associated with this detailed fuel injection model. These include the effect of mesh resolution on the spray boundary condition, the need for blockage modeling, and the need for ligament breakup modeling.
Scavenge Performance of an Optimized Shallow Sump at Various Flow Conditions
Authors: Chandra Budi , Johnson Kathy 
Published: January 2021

Abstract
Oil scavenge flow in aero-engine bearing chamber remains largely a challenging problem for many engine designers. Research campaign on scavenge flow has been conducted by G2TRC – Gas Turbine and Transmissions Research Centre (previously Rolls Royce University Technology Centre in Gas Turbine Transmission Systems) at the University of Nottingham. It was recognized that a deep sump performs better than shallower one due to its ability to “shield” the collected oil in the sump from the shaft windage thus reducing the amount of oil being picked up by the bulk air rotation. However, such a deep sump design cannot be employed in some engines and especially at certain locations where space is limited.
A parametric study combined with phenomenological approach on shallow sump geometry has been conducted and presented in the previous publication where a certain optimized shallow sump variant was proposed depending on whether the flow in the chamber is wall film dominated or airborne droplets dominated. The parametric phenomenological approach was employed since it can be done relatively quicker than typical data gathering through an experiment. However the approach relies on qualitative interpretation of the flow features, and its application in bearing chamber flow research has never been validated before. This paper presents the results of quantitative measurements of residence volumes of an optimized shallow sump variant identified in the parametric phenomenological study. Comparison was then made with the residence volumes of some existing engine sumps.
It was found that the optimized shallow sump for wall film dominated flow has lower residence volumes compared to some existing engine sumps. In some cases, the residence volume can be reduced by up to 75%. An optimized shallow sump variant for airborne droplets dominated was also identified in the previous parametric phenomenological study, although the residence volume measurement is yet to be conducted. The optimized shallow sump for wall film dominated flow was also identified as a good sump regardless of the flow regime. However when it was tested in airborne droplets dominated flow, its residence volumes are higher than some of the existing engine sumps. This highlights the importance of considering the flow regime in the bearing chamber in any attempt to optimize a sump geometry.
Numerical Investigations on the Heat Transfer Performance of Transonic Squealer Tip With Different Film Cooling Layouts
Authors: Jiang Shijie , Li Zhigang , Li Jun , Song Liming 
Published: January 2021

Abstract
Tip leakage flow in high speed turbine induce significant thermal loads and give rise to intense thermal stresses on blade tip, while increasing inlet pressure tends to accelerate leakage velocity beyond transonic regime. The present research quantifies heat transfer and film cooling effect on a squealer tip with three film cooling layouts, three coolant mass flow rates and a relative casing movement. The results indicate that area-averaged HTC of PS layout is higher than that of CAM layout by 6.9% and that of SS layout by 5.7% when coolant flow rate equals to 0.6% mainstream flow rate. By comparison, it is clearly observed that area of the high heat transfer coefficient regions are significantly enlarged when the flow rate of coolant is increased. With relative casing movement, a significant high HTC stripe parallel to pressure side rim is formed. In case of the PS layout, heat transfer coefficient is reduced by 7.3% with casing movement. While in case of CAM layout and SS layout, heat transfer coefficient increased by 4.8% and 2.3% with casing movement, respectively. Detailed flow patterns with three film cooling layouts are also illustrated.
Split Training Method to Generate Data Driven Model for Gas Turbine Engine Anomaly Detection
Authors: Takiguchi Yu , Shiono Satoshi 
Published: January 2021

Abstract
This paper presents a new method named Split Training Method (STM) for generating a data driven model of gas turbine engines to be used for anomaly detection and prognosis. The data driven model in this study simulates the relationship among engine parameters, such as sensor outputs and control inputs from pilots. More accurate trend monitoring of the relationship among engine parameters enables earlier anomaly detection with high accuracy.
Machine learning techniques such as clustering, nonlinear regression, classification and optimization are used in STM. The input data for generating a simulation model is extracted from the training data by applying clustering algorithm to split into some clusters and outliers. This is why our method is named “Split” Training. Outliers are excluded from training data and each cluster of training data generates a simulation model with nonlinear regression. Data points in the test data are classified to each cluster and used for evaluation of the corresponding model accuracy. In order to generate the simulation model with the highest accuracy, training data extraction is optimized by changing clustering shapes. The shapes of the optimized clusters are unique to individual engines and simulation target parameters.
The novelty of STM is that the training data is selected in accordance with the characteristics of the data itself and not selected on the condition determined in advance.
The result of comparison between STM and the conventional method shows significant accuracy enhancement.
Techno-Economic Optimization of a Combined Cycle Combined Heat and Power Plant With Integrated Heat Pump and Low-Temperature Thermal Energy Storage
Authors: Garcia Jose , Smet Vincent , Guedez Rafael , Sorce Alessandro 
Published: January 2021

Abstract
The present study presents a techno-economic analysis of a novel power plant layout developed to increase the dispatch flexibility of a Combined Cycle Gas Turbine (CCGT) coupled to a District Heating Network (DHN). The layout includes the incorporation of high temperature heat pumps (HP) and thermal energy storage (TES). A model for optimizing the short-term dispatch strategy of such system has been developed to maximize its operational profit. The constraints and boundary conditions considered in the study include hourly demand and price of electricity and heat, ambient conditions and CO2 emission allowances. To assess the techno-economic benefit of the new layout, a year of operation was simulated for a power plant in Turin, Italy. Furthermore, different layout configurations and critical size-related parameters were considered. Finally, a sensitivity analysis was made to assess the performance under different market scenarios.
The results show that it is indeed beneficial, under the assumed market conditions, to integrate a HP in a CCGT plant coupled to a DHN, and that it remains profitable to do so under a variety of market scenarios. The best results for the assumed market conditions were found when integrating a 15 MWth capacity HP in the 400 MWel CCGT-CHP. For this case study, the investment in the HP would yield a net present value (NPV) of 1.22 M€ and an internal rate of return (IRR) of 3.04% for a lifetime of 20 years. An increase was shown also in operational flexibility with 0.14% of the electricity production shifted while meeting the same heating demand. Additionally, it was found that the TES makes the system even more flexible, but does not make up for the extra investment.
Effect of Reynolds Number on Five-Hole Probe Performance: Experimental Study of the Open-Access Oxford Probe
Authors: Passmann Maximilian , aus der Wiesche Stefan , Povey Thomas , Bergmann Detlef 
Published: January 2021

Abstract
There is relatively little literature concerning the effect of Reynolds number on multi-hole aerodynamic probe performance. In particular, there is almost no discussion in the literature of the underlying mechanisms of Reynolds number (Re) sensitivity for such probes. In order to close this gap, detailed investigations of the effect of Re on a five-hole probe have been performed using both PIV techniques and oil flow visualizations. Wind- and water-tunnels were used to cover a wide range of Re. The open-access Oxford Probe was used for these studies because of the readily available data-sets and processing routines, and to allow future comparisons by other authors. Complex flow dynamics including flow separation and re-attachment were identified, which cause Re-sensitivity of the calibration map at low Re even for low yaw or pitch angles.
By comparing calibration maps across a wide range of Re, we demonstrate that the Oxford Probe can be employed without much loss of accuracy at lower Re levels than initially (conservatively) suggested, and quantify the errors in the extreme low-Re regime.
Overall we demonstrate the robustness of the Oxford Probe concept across a wide range of Re conditions, we more clearly defined the low-Re limit for the probe design and quantify errors below this limit, and we illustrate the fundamental mechanisms for Re-sensitivity of multi-hole probes.
Enhanced Early Warning Diagnostic Rules for Gas Turbines Leveraging on Bayesian Networks
Authors: Escobedo Ernesto , Arguello Liliana , Sepe Marzia , Parrella Ilaria , Cioncolini Stefano , Allegorico Carmine 
Published: January 2021

Abstract
The monitoring and diagnostics of Industrial systems is increasing in complexity with larger volume of data collected and with many methods and analytics able to correlate data and events.
The setup and training of these methods and analytics are one of the impacting factors in the selection of the most appropriate solution to provide an efficient and effective service, that requires the selection of the most suitable data set for training of models with consequent need of time and knowledge.
The study and the related experiences proposed in this paper describe a methodology for tracking features, detecting outliers and derive, in a probabilistic way, diagnostic thresholds to be applied by means of hierarchical models that simplify or remove the selection of the proper training dataset by a subject matter expert at any deployment.
This method applies to Industrial systems employing a large number of similar machines connected to a remote data center, with the purpose to alert one or more operators when a feature exceeds the healthy distribution.
Some relevant use cases are presented for an aeroderivative gas turbine covering also its auxiliary equipment, with deep dive on the hydraulic starting system.
The results, in terms of early anomaly detection and reduced model training effort, are compared with traditional monitoring approaches like fixed threshold.
Moreover, this study explains the advantages of this probabilistic approach in a business application like the fleet monitoring and diagnostic advanced services.
Parameter Estimation and Performance Seeking of a Marine Gas Turbine Based on Extended Kalman Filter
Authors: Wang Zhitao , Zhang Junxin , Qi Wanling , Li Shuying 
Published: January 2021

Abstract
Marine gas turbines have been widely used and developed in the field of marine power. It is important to make them operated safely and efficiently. In this paper, a marine triaxial gas turbine is taken as an example to study the method of estimating the health state of the gas path using extended Kalman filter (EKF). To verify the accuracy of EKF, a comparison was made between linearized Kalman filtering (LKF) and EKF. In addition, the sequential quadratic programming (SQP) algorithm is used to seek the performance in case of gas path abnormal. The combination of parameter estimation and performance seeking forms a comprehensive method for diagnosis and optimization of marine gas turbines.
The results show that the EKF method is an effective method for combining nonlinear systems with traditional Kalman filter. EKF has a good estimation effect on the gas path health state under different operating conditions. Also, the marine triaxial gas turbine achieved the target performance under the constraints of the SQP algorithm. Performance seeking restores the output power of the marine gas turbine and reduces the inlet and outlet temperatures of turbines. It can effectively prevent the problem of excessive combustion and ensure the safe and stable operation of the marine gas turbine.
Soot Emission Optimization of a Helicopter Engine: From Injector Design to Engine Tests Validation
Authors: Duchaine Patrick , Bouyssou Quentin , Pascaud Stéphane , Exilard Gorka , Viguier Christophe 
Published: January 2021

Abstract
Even though no regulation currently exists on helicopter gas turbines, soot production in aeronautic engines is of paramount importance to comply with future rules, as well as to offer environmental-friendly products on the market. Thus, design modifications of the combustion liner and fuel injectors are one way to explore in order to reduce soot emission levels of existing combustors. These design changes are driven both by fundamental knowledge of soot production mechanisms and by advanced combustion and pollutants modelling. The major difficulty is to reduce soot emissions while not deteriorating other combustion performances: NOx and CO emissions, lean blow-off limits and service lifetime.
The objective of the present study is to optimize fuel injectors of a recent Safran Helicopter Engines research combustor. The injector design modifications are driven by one main guideline: reducing soot emissions can be achieved by lowering the equivalence ratio downstream of the injector. Detailed designs are achieved thanks to advanced RANS injector and LES combustion computations.
Then, in order to mitigate main identified risks — management of soot emissions and lean blow-off limits — engine tests were performed very early in the demonstration process. A combustor is successively equipped with one standard and two modified geometries of fuel injectors on an engine test bench. Experimental results show that the two modified injector geometries reduce smoke numbers by a factor of respectively 2 and 9 and slightly deteriorates lean blow-off limits. These measurements are also compared to CFD computations. Leung et al. model (Combust Flame 1991), relying on phenomenological descriptions of soot formation combined with a LES computation of the combustor, well predicts a significant decrease in smoke level, even if it does not perfectly match engine data. Concerning lean blow-off limits, LES modelling predict a decrease in lean blow-off limits, which do not agree qualitatively with engine test results.
As a conclusion, this study identifies a design driving factor for soot reduction, with possibly acceptable impacts on other combustion performances like lean blow-off limits.
Experimental and Numerical Investigation of Ultra-Wet Methane Combustion Technique for Power Generation
Authors: Zhang Kai , Dybe Simeon , Shen Yazhou , Schimek Sebastian , Paschereit Christian Oliver , Duwig Christophe 
Published: January 2021

Abstract
Using steam as a heat carrier and working media has merits to increase electric efficiency up to 60% and decrease NOx emission to single-digit compared to dry gas turbine cycles. These attribute primarily to the physical properties of steam as having high heat capacity to reduce local flame temperature, and hence reduce emissions by inhibiting the thermal NOx forward reaction rate. In this work, ultra-high steam content with a steam-to-air mass ratio of up to 40% is premixed with methane-air mixture before entering into a swirl-stabilized HP-burner for combustion. A significant change of flame from V-shape (attached) to M shape (detached) is observed through a transparent combustion chamber whilst changing steam content. The measurement of chemiluminescence OH* is conducted with an intensified CCD-camera band-pass filtered at 320nm. Following these measurements, large eddy simulation is used to capture reacting flow features. Reasonably well agreements between experimental data and numerical results are obtained for both attached and detached flames in terms of the OH* distribution. Slight inconsistency of OH* intensity is mainly due to uncollected wall temperature which leads to either over- or under-prediction of chemical reaction rate depending on the experimental flame positions. Distributed flame front is clearly identified with LES for wet methane combustion associated with 35% steam-to-air ratio corresponding to a high Karlovitz number flame. Slightly unstable combustion is observed when the steam-to-air ratio exceeds 40% featuring an onset of flame blow-off. In addition, interaction between precessing vortex core and the flame is presented for different level of steam dilution, and conclusions are drawn regarding the flame stabilization. The in-depth understanding of the ultra-wet combustion is an important step towards the use of sustainable, steam-diluted biosyngas for electricity production.
Very Large Eddy Simulation of Flow and Heat Transfer in a Pulsating Impinging Jet
Authors: Liu Fangyuan , Mao Junkui , Han Xingsi , Xia Zhaoyang 
Published: January 2021

Abstract
The steady impinging jets applied in turbomachine have been comprehensively studied but the pulsating jets still need to be further researched. The flow field and heat transfer characteristics of pulsating impinging jet impinging on a flat plate have been simulated using the improved very large eddy simulation established with SST k–ω model. Two time-mean Reynolds numbers (6,000 and 23,000) in the conditions of frequency = 10Hz and steady state at the constant jet–to–surface distance (6D) were considered. The velocity, vortices, and Nusselt number distributions on the plate surface were investigated to emphasize on the vortex structures in the flow and its relation to the heat transfer. The investigation has revealed the advantage of the improved very large eddy simulation for predicting the dynamical generating process of flow structures in pulsating jets. Calculated results showed pairs of vortices were organized and induced from the jet exit, and propagated along with the jet region periodically. The vortices grew with the entrainment towards the ambient fluid and resulted in accelerated interaction in the wall jet region. Meanwhile, the vortices had strong interaction with the core region and weakened velocity in the core region. Results showed that the time–mean local Nusselt number of pulsating jet was lower in the stagnation region at both investigated Re numbers but not reduced in the wall jet region.
Numerical Simulation Model of Electrothermal De-Icing Process on Composite Substrate
Authors: Guo Xiaofeng , Guo Zhiqiang , Yang Qian , Dong Wei 
Published: January 2021

Abstract
A numerical simulation model of electrothermal de-icing process on carbon fiber reinforced polymer (CFRP) composite is conducted to study the effect of thermal properties of the substrate on the ice melting process. A novel melting model which is based on the enthalpy-porosity method is applied to study the transient ice melting process and heat transfer of the de-icing sys-tem. Multi-layered electrothermal de-icing systems including composites with different fiber orientation are used to analyze the effects of orthotropic heat conductivity of the CFRP composite on the ice melting process and heat transfer. Movement of the ice-water interface, the melted zone thickness and the melted zone area on CFRP composite are investigated on the three-dimensional electrothermal de-icing unit. The effects of thermal properties of substrate on the temperature distribution of the ice-airfoil interface are analyzed. The computational results show that the thermal properties of substrates affect the temperature on the ice-airfoil interface, the temperature distribution in the substrate, ice melting area, ice melting rate and ice melting volume significantly. The time that ice starts to melt on the CFRP composite substrate is earlier than that on the metal substrate. However, it takes more time for the ice to melt completely on the ice-CFRP interface than that on the ice-metal inter-face. The orthotropic heat conductivity of CFRP composite results in strong directivity of the melting area on the ice-CFRP in-terface. A ratio parameter is defined to represent the matching degree of substrate materials and geometry model of de-icing system. The simulation model can be applied to study electrothermal de-icing system of nacelle inlet and airfoil made of composite. The results in present work is also helpful to predict the change of temperature during de-icing process and provide guidelines for the optimizing the electrothermal de-icing system to reduce power consumption according to the fiber structure of composite.