bluuebunny/crossref_metadata_2025_split huggingface dataset:
A Marine Turbocharger Compressor Multi-Point 3D Design Optimization Tool
Authors: Ntonas Konstantinos , Aretakis Nikolaos , Mathioudakis Konstantinos 
Published: September 2021

Abstract
A marine turbocharger 3D compressor design tool, implemented on an existing marine turbocharger retrofit platform is presented. It produces 3D centrifugal compressor geometry for optimal compressor retrofit. It encompasses two modules, allowing the design process to become fully automatic.
First, a 1D compressor multi-point design optimization process is carried out, aiming to provide a fast and reliable solution based on Turbocharged diesel Engine range of operation. Structural integrity is ensured by using simplified structural analysis. Dimensionless parameters are used as optimization variables, for a given nominal compressor mass flow and power. Then a CFD compressor multi-point design optimization process is carried out, producing optimized 3D compressor geometry. It complies with the Turbocharged diesel Engine range of operation, while structural integrity is ensured by using Finite Element analysis.
A turbocharger compressor design case study is presented. First, a turbocharger 1D compressor design is carried out, aiming to at least reconstituting the original diesel engine performance. This first module provides a reliable compressor initial geometry for the 3D design module. A fully 3D compressor design is then performed, using a CFD-FEA optimization process, in order to provide an improved retrofitting solution.
Comparison between the multi-point and the traditional one-point design method, shows that the multi-point method provides a wider SFC reduction in the range that the Diesel engine normally operates.
Challenges With Measuring Supercritical CO2 Compressor Performance When Approaching the Liquid-Vapor Dome
Authors: Mortzheim Jason , Hofer Doug , Priebe Stephan , McClung Aaron , Moore J. Jeffery , Cich Stefan 
Published: September 2021

Abstract
A team led by General Electric Research (GER) and Southwest Research Institute (SwRI) was tasked to design, build and test an advanced 4MW CO2 compressor that would operate near the liquid-vapor dome for Carbon Dioxide (CO2). The US Department of Energy (DoE) Solar Technologies Office (SETO) funded program was targeted towards a Concentrated Solar Power (CSP) plant where optimum power cycle efficiency can be obtained when operated close to the liquid-vapor dome where CO2 is a supercritical fluid (sCO2) as compression power is reduced in the main compressor. However, the CSP cycle and other related supercritical CO2 cycles (fossil, nuclear, waste heat recovery) have considerable compression challenges both mechanically and aerodynamically when operating with a high density fluid that exceeds 70% the density of water. The subject of this paper is highlighting the challenge in determining compressor performance using industry standard measurements. This application is the highest density industrial-scale centrifugal compressor in the world at 720 kg/m3.
This paper will investigate the uncertainty when measuring compressor efficiency using ASME PTC-10 instrumentation and the effect of the strong CO2 property variation when operating as a supercritical fluid, near the fluid-vapor dome. Prior work in this area by Wahl will be summarized and compared with the current compressor test program uncertainty. It will be shown that Wahl predicted high uncertainty as well although, the current testing program is even closer to the liquid-vapor dome than the test program under Wahl.
The uncertainty analysis has shown that traditional PTC-10 temperature measurements lead to high levels of uncertainty for sCO2 compression near the liquid-vapor dome. The uncertainty is driven by the large changes in thermodynamic properties of sCO2. These property changes are affected by the measured pressure and temperature; however, temperature measurement error is the primary contributor to uncertainty. Because of this, looking at alternate sCO2 property measurements was investigated. Higher quality localized pressure calibration, improving flow measurement accuracy, and measuring density in addition to temperature all significantly improved efficiency uncertainty. The authors confirmed the most significant measurement change is to measure pressure and density through either a densitometer or a Coriolis flow meter which provides a density measurement in conjunction with flow rate accuracy.
Implementation of Vortex Generator and Ramp to Improve Film Cooling Effectiveness on Blade Endwall
Authors: Hussain Sadam , Yan Xin 
Published: September 2021

Abstract
With the arrangements of vortex generators (VG) and ramp, film cooling effects on endwall near leading edge were numerically investigated at two blowing ratios (i.e. M = 0.5 and M = 1). To determine suitable numerical methods, mesh independency analysis and turbulence model selection were carried out based on the existing experimental data and LES results. With the numerical methods, flow fields near the leading edge were visualized to illustrate the influence of VG and ramp on coolant coverage on blade endwall. Film cooling effectiveness distributions on endwall and coolant trajectories near leading edge were compared among five different configurations with VG and ramp. The results show that the attachment of coolant on blade endwall is improved with the implement of VG between shaped-hole and leading edge. With the implementation of ramp on endwall between cooling hole and leading edge, the coolant spreads wider on endwall along pitchwise direction than the baseline case. With the implementation of VG and ramp, film cooling effect on endwall near leading edge is significantly improved as compared with the only ramp and only VG cases. Compared with the baseline case, pitchwise-averaged film cooling effectiveness on blade endwall near leading edge is increased by about 9%, and the film cooling effectiveness distributions on endwall along pitchwise direction become much uniform, for the case with both ramp and VG at M = 1.
Prediction of CO Emission Index for Aviation Gas Turbine Combustor Using Flamelet Generated Manifold Combustion Model
Authors: Patwardhan Saurabh , Nakod Pravin , Orsino Stefano , Yadav Rakesh , Xu Fang , Verma Vishwas 
Published: September 2021

Abstract
Carbon monoxide (CO) has been identified as one of the regulated pollutants and gas turbine manufacturers target to reduce the CO emission from their gas turbine engines. CO forms primarily when carbonous fuels are not burnt completely, or products of combustion are quenched before completing the combustion. Numerical simulations are effective tools that allow a better understanding of the mechanisms of CO formation in gas turbine engines and are useful in evaluating the effect of different parameters like swirl, fuel atomization, mixing etc. on the overall CO emission for different engine conditions like idle, cruise, approach and take off. In this paper, a thorough assessment of flamelet generated manifold (FGM) combustion model is carried out to predict the qualitative variation and magnitude of CO emission index with the different configurations of a Honeywell test combustor operating with liquid fuel under idle condition, which is the more critical engine condition for CO emission. The different designs of the test combustor are configured in such a way that they yield different levels of CO and hence are ideal to test the accuracy of the combustion model. Large eddy simulation (LES) method is used for capturing the turbulence accurately along with the FGM combustion model that is computationally economical compared to the detailed/reduced chemistry modeling using finite rate combustion model. Liquid fuel spray breakup is modeled using stochastic secondary droplet (SSD) model. Four different configurations of the aviation gas turbine combustor are studied in this work referring to earlier work by Xu et al. [1]. It is shown that the FGM model can predict CO trends accurately. The other global parameters like exit temperature, NOx emissions, pattern factor also show reasonable agreement with the test data. The sensitivity of the CO prediction to the liquid fuel droplet breakup model parameters is also studied in this work. Although the trend of CO variation is captured for different values of breakup parameters, the absolute magnitude of CO emission index differs significantly with the change in the values of breakup parameters suggesting that the spray has a larger impact on the quantitative prediction of CO emission. An accurate prediction of CO trends at idle conditions using FGM model extends the applicability of FGM model to predict different engine operating conditions for different performance criteria accurately.
Coupled Time and Passage Spectral Method for an Efficient Resolution of Turbomachinery Far Upstream Wakes
Authors: Wang Dingxi , Zhang Sen , Huang Xiuquan , Huang Huang 
Published: September 2021

Abstract
The paper proposes a novel numerical method called coupled time and passage spectral method for an efficient resolution of far upstream wakes in an unsteady analysis of flow field within generic multiple blade rows. The proposed method is a very simple and natural extension of the time spectral form harmonic balance method. By including inter blade phase angle and passage index in a truncated Fourier series, the proposed method is capable of circumventing the limitations of the harmonic balance method in dealing with zero frequency harmonics and time harmonics with same frequency but different inter blade phase angles. Different from the harmonic balance method, which seeks solution at different time instants of the same passage, the coupled spectral method seeks solutions at different passages and time instants. Same as the harmonic balance method, all these solutions are connected via a spectral operator. Coupled time and passage sampling is performed using the modified Gram Schmidt process to choose the time and passage pairs which give the most orthogonal rows of an inverse Fourier transform matrix. The coupled time and passage spectral method requires minimum change to an existing harmonic balance solver. A numerical case study has been provided in the paper to demonstrate the expected capability against the harmonic balance method.
Rotordynamic Characteristics of the Straight-Through Labyrinth Seal Based On the Applicability Analysis of Leakage Models Using Bulk-Flow Method
Authors: Wang Tianhao , Li Zhigang , Li Jun 
Published: September 2021

Abstract
Labyrinth seals are widely applied in the turbomachinery to control the leakage flow through the clearance between the stationary and rotating components. The fluid excitation induced by the labyrinth seal would deteriorate the stability of turbomachinery shaft. Developing an accurate and rapid prediction approach is crucial for the analysis of the fluid excitation rotordynamics of the labyrinth seal. The objective of this study is to analyze the applicability of leakage models using Bulk-Flow method and investigate the factors affecting the rotordynamic characteristics of the labyrinth seal. An elliptical orbit for rotor whirling was assumed in the one-control-volume Bulk-Flow model considering an isentropic process to predict the frequency-dependent rotordynamic coefficients of the labyrinth seal. The optimal leakage model was determined by comprehensively analyzing the applicability of 72 leakage models. Employing the optimal leakage model in the Bulk-Flow method, the effects of sealing clearance, pressure ratio, preswirl ratio and rotational speed on the rotordynamic characteristics of the labyrinth seal were investigated. The conclusions show that the Bulk-Flow method has an average prediction error of around 10% for the leakage flow rate, cross-coupled stiffness and direct damping when equipped with the optimal leakage model. Increasing preswirl ratio has a significantly destabilizing effect on the rotor stability, while the influence of increasing rotational speed is strongly related to preswirl direction. The effective damping of the labyrinth seal is sensitive to the inlet pressure, but insensitive to the outlet pressure and sealing clearance. The crossover frequency is almost impervious to the inlet pressure, outlet pressure and sealing clearance.
Correlating Time-Resolved Pressure Measurements With Rim Sealing Effectiveness for Real-Time Turbine Health Monitoring
Authors: DeShong Eric T. , Peters Benjamin , Berdanier Reid A. , Thole Karen A. , Paynabar Kamran , Gebraeel Nagi 
Published: September 2021

Abstract
Purge flow is bled from the upstream compressor and supplied to the under-platform region to prevent hot main gas path ingress that damages vulnerable under-platform hardware components. A majority of turbine rim seal research has sought to identify methods of improving sealing technologies and understanding the physical mechanisms that drive ingress. While these studies directly support the design and analysis of advanced rim seal geometries and purge flow systems, the studies are limited in their applicability to real-time monitoring required for condition-based operation and maintenance. As operational hours increase for in-service engines, this lack of rim seal performance feedback results in progressive degradation of sealing effectiveness, thereby leading to reduced hardware life.
To address this need for rim seal performance monitoring, the present study utilizes measurements from a one-stage turbine research facility operating with true-scale engine hardware at engine-relevant conditions. Time-resolved pressure measurements collected from the rim seal region are regressed with sealing effectiveness through the use of common machine learning techniques to provide real-time feedback of sealing effectiveness. Two modelling approaches are presented that use a single sensor to predict sealing effectiveness accurately over a range of two turbine operating conditions. Results show that an initial purely data-driven model can be further improved using domain knowledge of relevant turbine operations, which yields sealing effectiveness predictions within three percent of measured values.
Impact of Ceramic Matrix Composite Topology on Friction Factor and Heat Transfer
Authors: Cory Trevor M. , Edelson Ryan D. , Thole Karen A. , Vincent Tyler , Quach San , Mongillo Dominic 
Published: September 2021

Abstract
Ceramic matrix composites (CMCs) are of interest for hot section components of gas turbine engines due to their low weight and favorable thermal properties. To implement this advanced composite in a gas turbine engine, characterizing the influence of CMC’s surface topology on heat transfer and cooling performance is critical. However, very few published studies have reported the flow and heat transfer effects caused by this unique surface topology. This study is an experimental and computational investigation to evaluate the effect of weave orientations, relevant to CMC surfaces, on the resulting pressure loss and convective heat transfer within an internal channel. The weave pattern was additively manufactured as the walls of a scaled-up coupon containing a single channel. For each of the three weave orientations, bulk pressure losses and convective heat transfer coefficients were measured over a range of Reynolds numbers.
Scaling the pressure losses in terms of a friction factor and convective heat transfer coefficients in terms of a Nusselt number showed the importance of choosing the appropriate definition of the hydraulic diameter, which was particularly important for the friction factor. A coupon having one wall with the weave surface increased pressure loss and heat transfer compared to a smooth wall with the largest increases occurring when the CMC weave strands were perpendicular to the flow. Friction factor augmentations were much higher than heat transfer augmentations. When adding the weave to a second channel wall, pressure loss and heat transfer were further increased. Orienting the CMC strands perpendicular to the flow consistently showed the largest augmentations in heat transfer over a smooth channel, but at a much higher pressure loss penalty than that seen with the CMC strands parallel to the flow.
Comprehensive Performance Improvement for a 16-Stage Axial Compressor
Authors: Popov Grigorii , Miheev Maxim , Vorobyev Alexey , Baturin Oleg , Zubanov Vasilii 
Published: September 2021

Abstract
The paper describes the process of gas-dynamic modernization of a 16-stage axial compressor of an industrial gas turbine unit. Tests of the baseline variant of the compressor revealed a significant shortfall of efficiency, pressure ratio, and stability margins. In addition, the ongoing work on the modernization of the entire engine sets the task to the authors of not just achieving design parameters but significantly exceeding them (air mass flow rate by 6%, pressure ratio by 2%, adiabatic efficiency by 1% relative to the design values).
To achieve these goals, a numerical model of the compressor was developed and validated. The characteristics obtained with its help were carefully analyzed. It was found that the front stage group has low efficiency, and the rear stage group is significantly oversized in terms of mass flow rate.
Modernization works were significantly hampered by the presence of many stages and many independent variables. For this reason, the problem was solved in several stages. A separate modernization of the first and rear groups of stages was performed. Moreover, methods of mathematical optimization were used when developing the rear block of 10 stages. Then the working processes of the compressor parts were matched.
As a result of the research, a variant was found to modernize the existing 16-stage axial compressor, providing an increase in the air mass flow rate by 18%, adiabatic efficiency by 3.5%, and margins of gas-dynamic stability up to 16%.
Recursive Sequential Combustion: A Concept Study About a Momentum-Enhanced Blend of the Reactants With Recirculated Burnt Gases
Authors: Giuliani Fabrice , Paulitsch Nina , Hofer Andrea 
Published: September 2021

Abstract
Over the last decade, new concepts have evolved to promote a significant azimuthal flow in annular combustors of gas turbines. The benefits are better flame propagation at ignition, positive flame-flame interaction, and better interaction with the burnt gases. Other advantages in terms of size, congestion and conditioning of the turbine inlet flow are also significant. The technical challenges reported by the literature are often related to the higher thermal stress of the flames on the walls compared to a conventional frame. Other sources of inspiration for this work are the principles of burnt gas recirculation, sequential combustion and flameless combustion.
This contribution focuses on a novel tangential burner arrangement inspired by the previous references. It offers a synthesis of key features and properties of the latter and goes even further. Here, a significant part of the burnt gases produced by one burner intentionally enters the inlet of the next burner, and so on along the azimuthal direction. This takes advantage of the closed loop aspect of an annular combustor when considering the toroidal direction. It also proposes a solution to the thermal load problem. We named this principle Recursive Sequential Combustion (RSC).
While the flame alignment is organised along the generatrix of the combustor’s annulus, one difficulty lies in the design of the lateral feeds of reactants and the lateral exit of the exhaust gases. A double-spiral combustor design is proposed, which has similarities with the Swiss Roll Combustor concept. It directs the flow in the toroidal direction, as well as it creates the favourable conditions for a dynamically stabilised premixed flame centred along the torus’ generatrix at some distance from the walls. This design maximises the interaction between the fresh reactants and the burnt gases. The technical challenge is to find the right balance in terms of momentum flux of the incoming and outgoing flows to keep the flame in the middle of the torus. If this concept is successful, a lean flame could be operated with an unmatched trade-off between stability, flexibility and low-emissions (including soot). The paper reports about the RSC concept, the design, and the early results.
Effect of a Ceramic Matrix Composite Surface on Film Cooling
Authors: Wilkins Peter H. , Lynch Stephen P. , Thole Karen A. , Quach San , Vincent Tyler , Mongillo Dominic 
Published: September 2021

Abstract
Ceramic matrix composite (CMC) parts create the opportunity for increased turbine entry temperatures within gas turbines. To achieve the highest temperatures possible, film cooling will play an important role in allowing turbine entry temperatures to exceed acceptable surface temperatures for CMC components, just as it does for the current generation of gas turbine components. Film cooling over a CMC surface introduces new challenges including roughness features downstream of the cooling holes and changes to the hole exit due to uneven surface topography. To better understand these impacts, this study presents flowfield and adiabatic effectiveness CFD for a 7-7-7 shaped film cooling hole at two CMC weave orientations. The CMC surface selected is a 5 Harness Satin weave pattern that is examined at two different orientations. To understand the ability of steady RANS to predict flow and convective heat transfer over a CMC surface, the weave surface is initially simulated without film and compared to previous experimental results. The simulation of the weave orientation of 0°, with fewer features projecting into the flow, matches fairly well to the experiment, and demonstrates a minimal impact on film cooling leading to only slightly lower adiabatic effectiveness compared to a smooth surface. However, the simulation of the 90° orientation with a large number of protruding features does not match the experimentally observed surface heat transfer. The additional protruding surface produces degraded film cooling performance at low blowing ratios but is less sensitive to blowing ratio, leading to improved relative performance at higher blowing ratios, particularly in regions far downstream of the hole.
Measurement of Heat Transfer and Flow Structures in a Closed Rotating Cavity
Authors: Jackson Richard W. , Tang Hui , Scobie James A. , Owen J. Michael , Lock Gary D. 
Published: September 2021

Abstract
Buoyancy-induced flow occurs inside the rotating compressor cavities of gas turbines. These cavities are usually open at the inner radius, but in some industrial gas turbines, they are effectively closed. This paper presents measurements of the disc heat transfer and rotating flow structures in a closed cavity over a wide range of engine relevant conditions. These experimentally derived distributions of disc temperature and heat flux are the first of their kind to be published. The radial distribution of the non-dimensional disc temperature virtually collapsed onto a single curve over the full experimental range. There was a small, monotonic departure from this common curve with increasing Reynolds number; this was attributed to compressibility effects where the core temperature increases as the rotational speed increases. These results imply that, if compressibility effects are negligible, all rotating closed cavities should have a disc temperature distribution uniquely related to the geometry and disc material; this is of important practical use to the engine designer. Unsteady pressure sensors detected either three or four vortex pairs across the experimental range. The number of pairs changed with Grashof number, and the structures slipped relative to the rotating discs by less than 1% of the disc speed.