bluuebunny/crossref_metadata_2025_split huggingface dataset:
Waste Heat Recovery Driven Turbocharger System for Gas Turbine
Authors: Sammak Majed , Jupudi Maruthi , Dawood Alaaeldin , Khalidi Abdurrahman 
Published: October 2022

Abstract
This paper introduces a novel concept for power augmentation by waste heat recovery turbocharger system. The turbocharger system, coupled to an external air compressor, is driven by the exhaust gases waste heat. The air compressor then compresses additional air that will be injected into the gas turbine compressor discharge and boost the gas turbine power. As the heat recovery system drives the turbocharger with heat recovered from the exhaust gas stream, the power produced by the power generation system increases without decreasing the efficiency.
Compressed air injection helps with resorting the missing gas turbine compressor air at high ambient temperatures and thus the compressed air injection is more suitable for gas turbines operating at hot ambient conditions. The paper also investigates utilizing the waste heat recovery turbocharger system at gas turbine part load operation for fuel saving and heat rate improvements.
This paper analyzes the gas turbine simple cycle power improvements at different ambient conditions and compressed air injection percentage. The gas turbine power proved to increase by around 2% at 1% air injection and 10% at 5% air injection at high ambient temperatures 30°C, 40°C and 50°C. Furthermore, the gas turbine heat rate improvement landed at 6.5% at 50°C and 5% air injection.
This study also compares the waste heat recovery system with other power augmentation technologies, namely the inlet mechanical chiller and the evaporative cooler.
Compared to a gas turbine with waste heat recovery turbocharger air injection system at 5% air injection, the electrical chiller system increases the gas turbine heat rate by around 2% assuming chiller COP of 5.
The waste heat recovery turbocharger system offers both power augmentation and heat rate improvements for simple cycle gas turbines. Additionally, this system can extend the hot gas path life by lowering the firing temperature without losing power.
Analysis of Turbomachinery Averaging Techniques
Authors: Frey Christian , Ashcroft Graham , Müller Michael , Wellner Jens 
Published: October 2022

Abstract
In this paper, various averaging techniques commonly used in turbomachinery applications are analyzed. It is shown how the work average relates to Miller’s mechanical work potential and that it is, in a certain way, consistent with Hartsel’s cooled turbine efficiency. It is found that a key to understand these approaches is to analyze the impact that entropy variations at inflows have on them.
Second-order asymptotics of mixing entropy are used to establish a close relationship between flux and work averages. It is found that the mixing entropy asymptotic due to entropy modes is identical for both averages. The work average, along with Miller’s mechanical work potential analysis, is as optimistic as the entropy average for vorticity and acoustic modes, but as pessimistic as the flux averaging for entropy variations. This explains why mechanical work potential based analysis is pessimistic about the inflow and thus optimistic about the efficiency of a turbine for high entropy variations in the inflow, e.g. in the presence of hot streaks or film cooling.
Radial averaging techniques are discussed and their impact on turbine performance is shown. Our findings are illustrated by means of the analysis of steady and unsteady flow simulations of a 1.5 stage turbine configuration.
Crosswind Aerodynamic Analysis Using Quasi 3D Ducts
Authors: Sarvankar Sumit Shankar , Issai Arasu Adrin , Vadlamani Nagabhushana Rao 
Published: October 2022

Abstract
In this paper, we address the aerodynamics of the nacelle subjected to severe crosswinds. A series of numerical simulations are carried out on a Quasi 3D duct which has been extracted from a 3D axisymmetric nacelle. The operating characteristics of the Q3D duct, total pressure profiles at fan-face and isentropic Mach number distributions over the intake lip, are demonstrated to be in encouraging agreement with the experiments. Some of the strategies to predict two different types of hysteresis which are either observed at low mass flow rates or at lower operating pressures within the duct (and hence at low Reynolds numbers) are discussed. Contrasting trends in the turbulent kinetic energy predictions of k-ω and γ-Reθ models at low system pressures are observed, which indicate that the boundary layers on the windward side of the intake lip are transitional. Finally, we discuss the possibilities of improving the off-design nacelle performance using active plasma flow control. While a low-speed separation can be eliminated using plasma actuator, controlling high speed separation remains a challenging task.
Acoustic Signature of Flow Instabilities Present in Industrial Centrifugal Compressor
Authors: Liskiewicz Grzegorz , Jaeschke Andrzej , Kryłłowicz Władysław 
Published: October 2022

Abstract
In this paper the possibility of diagnosing the compressor flow stability by acoustic measurements is explored. A correlated acoustic signal was measured together with pressure in the flow channel. The method allowed to evaluate the applicability of acoustic measurements for simple diagnostics of machine working conditions. The advantage of acoustic study is that it can be conducted ad-hoc without installing any special equipment, does not interfere with the machine setting and does not require changing the working conditions. The biggest downside is the method accuracy, possible reflections and interference with the noise coming from another machines present in the room. Study was performed on a low speed industrial compressor. A set of acoustic measurements was conducted in 7 locations to observe the influence of possible reflections. Study included continuous voice recording made at constant flow conditions and signals gathered during continuous closure of the throttling valve - on the way to the surge. Study confirmed that the microphone noise measurement allows to distinguish the main unstable flow phenomena. It could be potentially used as an initial test of flow stability in industrial centrifugal compressor or even predict the surge proximity.
Rotor37 Aerodynamic Optimization: A Machine Learning Approach
Authors: Beqiraj Klajdi , Perrone Andrea , Sanguineti Marco , Ratto Luca , Ricci Gianluca 
Published: October 2022

Abstract
The present paper presents an enhanced method for aerodynamic optimization of NASA Rotor37 row based on Machine Learning (ML) algorithms. An aerodynamic database has been developed using a commercial 3D (three dimensional) computational fluid dynamics (CFD) solver; a RANS (Reynold Averaged Navier Stokes) steady approach with a two-equation SST (Shear Stress Transport) model has been adopted for the aerodynamic computations.
The database geometries have been parametrized through autoencoders with the aim of automatically extracting characteristic geometric features and obtaining extensive parameterization of the blade. Autoencoders are a specific type of Neural Network which allow to feed non-parametric CAD designs into ML models. The autoencoder latent parameters describe the blade 3D geometry and can be used as an alternative to the standard geometric parameters in describing the shape of each sample. The main advantage is that autoencoders enable an automatic parameterization of 3D geometries, thus overcoming the limits imposed by manual parameterization.
A Neural Network has been used in order to predict global performance (e.g., pressure ratio, efficiency) and 3D field quantities (pressure and temperature distribution).
The optimization through reinforcement learning algorithms has been carried out in order to maximize the blade efficiency; geometries have been generated by exploiting the latent parameterization obtained by autoencoder. The accuracy of the ML algorithm forecast has been evaluated through CFD simulations carried out on the optimal sample. The results related to the optimized sample have been presented and highlight all the benefits of the proposed approach.
Experimental Investigation of a High-Speed Turbine With Rainbow Rotor and Rim Seal Purge Flow
Authors: Cernat Bogdan , Pinho Jorge , Okada Mizuki , Lavagnoli Sergio 
Published: October 2022

Abstract
The present paper addresses the experimental and numerical study of the unsteady flow established in a high-pressure turbine stage with rim seal purge. The HPT test section, operated at engine-relevant flow conditions in the high-speed turbine rig of the von Karman Institute, is heavily instrumented for high-resolution, high-bandwidth aerothermal measurements. A rainbow rotor setup allows the simultaneous testing of six different sectors, each hosting a specific tip and platform geometry optimized for enhanced aerodynamic performance. This paper focuses on the flow over the baseline sector, equipped with an axisymmetric hub platform and a squealer tip, with a purge flow rate matching 1.74% and 1% of the stage mass flow. The numerical study relies on Reynolds-averaged Navier Stokes computations with test-calibrated boundary conditions.
Unsteady pressure and heat transfer measurements are performed at the rotor shroud. The maximum heat transfer is achieved along the front pressure side rim, whereas the squealer cavity generates a region of uniformly low static pressure and heat flux. The experimental adiabatic wall temperature is derived to quantify the thermal contribution to the global heat flux, demonstrating an increase in over-tip gas temperature up to 1.2 T01 above the pressure side rim. A Euler-based model is proposed to evaluate the temperature-driving work-exchange mechanism in the tip gap. The peak in casing heat transfer coefficient (750 W/m2) is found at the tip leading edge.
Time-resolved measurements of outlet total pressure, Mach number, and flow angle confirm the predicted phase and intensity of the tip leakage and upper passage vortex in the near-casing region. At 20% hr, the total pressure minimum is highly under-predicted by the RANS, indicating an inaccurate modeling of the interaction between rim seal purge and main flow. The measured impact of the purge flow variation is more significant than predicted by the RANS computations, with a negative offset of about 0.5% P01 in the lower 50% hr at lower purge flow rate.
Effects of Turbine Conditions on Rim Seal Performance and Prediction
Authors: Burden Shaun , Chew John W. , Gao Feng , Marxen Olaf 
Published: October 2022

Abstract
Predicting the degree of hot gas ingestion into turbine disc cavities is a challenge for computational fluid dynamics due to the complex unsteady flow dynamics in turbine rim seals and sensitivity to operating condition and seal geometry. This paper reports research aimed at clarifying the effect of operating conditions on seal performance and turbulence modelling requirements. A systematic study of sealing performance for an axial rim seal is reported, comparing an unsteady Reynolds-averaged Navier-Stokes (URANS) model and wall-modelled large-eddy simulation (WMLES). The conditions considered are classed as rotation-driven ingestion, pressure-driven ingestion, and combined mechanism ingestion. WMLES and URANS results showed similar ingestion levels and seal flows within the pressure-driven regime. For the rotationally-driven condition URANS displays larger, more coherent vortical flow structures than the WMLES. The larger vortices in the URANS drive ingress into the wheel-space resulting in higher levels of ingestion than indicated by the WMLES. For the combined ingestion condition, WMLES shows higher levels of ingestion and flow unsteadiness than URANS. The present results give some explanation for the mixed results reported for the performance of URANS models in previous studies.
Mooring System Design and Analysis for a Floating Offshore Wind Turbine in Pantelleria
Authors: Ghigo Alberto , Niosi Francesco , Paduano Bruno , Bracco Giovanni , Mattiazzo Giuliana 
Published: October 2022

Abstract
The mooring system plays a key role in a floating offshore wind turbine: it connects the floating structure to its anchor on the seabed and it is designed to prevent the platform from drifting under the action of wind, waves and currents. The layout of the mooring system is strictly connected to the installation site: in the first place it depends on the bathymetry and the type of seabed which conditions the type of anchor that can be used; secondly by the wind and waves loads in extreme sea states.
To properly design the mooring system, three different configurations are proposed and discussed, respectively adapting catenary, taut leg and semi-taut methodologies for a floating offshore wind turbine located near the island of Pantelleria, in Sicily. For each configuration, the Hexafloat foundation, developed by Saipem, is considered. Important design constraints such as how large the nominal sizes are, how long the mooring lines are, how far the anchor points are located, are demonstrated in detail. The material used will range from steel chains and wires to polyester ropes, to grant economically viable solutions.
A New Health Evaluation Approach for Gas Turbine Using Its Component Performance Parameters
Authors: Luan Junqi , Cao Yunpeng , Ao Ran , Han Xiaoyu , Li Shuying 
Published: October 2022

Abstract
Nonlinear gas path analysis (NGPA) is an important method for gas path fault diagnosis, and it is also the main technology for component performance estimation of gas turbine engines. However, the solution speed of the nonlinear gas path model is difficult to meet the time requirements of realtime performance evaluation due to the strong nonlinearity of the gas turbine model. In response to this problem, this paper proposes a new approach to gas turbine health evaluation based on component performance parameters. A nonlinear gas path model is established to realize the offline estimation of the performance parameters of the gas turbine components. The general regression neural network (GRNN) is introduced to realize the mapping between the operating data of the compressor wash cycle and the performance parameters of the components. The dimension of component performance parameters was reduced by principal component analysis (PCA) to extract degraded features by simplifying the complexity of the evaluation, and the health value (HV) is proposed to characterize the gas turbine health status. A health evaluation testing for the marine gas turbine was carried out. Compared with the NGPA method, the maximum average absolute percentage error, and root mean square error of the component performance parameters estimated by the proposed method are 0.384% and 0.336, respectively. The testing results show that the proposed method can estimate the component performance parameters of the gas turbine online, and realizes the evaluation of the health status of the gas turbine.
Establishing a Generic Stress-Life Framework for Single-Crystal Nickel-Base Superalloys
Authors: Irmak Firat , Karim Sahil , O’Nora Nathan , Gordon Ali P. 
Published: October 2022

Abstract
Selection of materials to be used for components experiencing extreme conditions is a critical process in the design phase. Nickel-base superalloys have been frequently used for hot gas path components in the turbomachinery industry. These components are required to withstand both fatigue and creep at extreme temperatures during their service time. In general, the extreme temperature materials mostly embody polycrystalline, directionally solidified, and single crystal superalloys. Single crystallization has been utilized with nickel-base superalloys since 1980s. This method forms one grain by eliminating all of the grain boundaries, which has resulted with thermal, fatigue and creep properties superior to conventional alloys. It is essential for design engineers to predict accurate damage behavior and lifespan for these components to prevent catastrophic failures. This study presents generic elastic and stress-life models for single crystal nickel-base superalloys based on observed trends. Despite the development of over 50 variations of single crystal Nickel-base superalloys, the behavior of these alloys nominally follows similar mechanical behavior trends with respect to temperature and orientation. Temperature-, rate-, and orientation-dependence of these materials are studied. In this study, [001], [011] and [111] orientations are mainly considered. The goal is to eliminate extensive time and cost of experiments by creating parameters to be used in life calculations for generic single crystal alloys. While the stress-based approach to fatigue analysis of materials was the first to be developed, it continues to endure with broad usage in a wide variety of engineering applications. These models tend to be used for the cases with high number of cycles to failure behavior or called high-cycle fatigue (HCF) conditions. In this work, the total damage is divided into two different modules; fatigue and creep damages. Miner’s Rule is utilized to combine these modules. Models which can predict the cycles to failure data with the most usage-like conditions and require least amount of data are preferred. Parameters for the models are built on regression fits in comparison with a comprehensive material database. This database includes elastic, plastic, creep, and fatigue properties.
Techno-Economic Comparison of Supercritical CO2, Steam, and ORC Cycles for WHR Applications
Authors: Baglietto Giovanni , Maccarini Simone , Traverso Alberto , Bruttini Paolo 
Published: October 2022

Abstract
Supercritical CO2 (sCO2) is taking a growing interest in both industry and academic communities as a promising technology capable of high efficiency, flexibility, and competitive capital costs. Many possible applications are studied in the energy field, from nuclear power plants to CSP and waste heat recovery (WHR).
To evaluate the competitiveness of sCO2 cycles relative to other competing technologies, mainly steam and ORC, a specific techno-economic analysis is needed to fairly compare the different technologies for each application, in order to find the most appropriate market position of the innovative sCO2 plants, compared to the existing steam and ORC solutions.
In the present study, techno-economic analysis and optimization have been conducted focusing on WHR applications, for different sizes and cycle parameters operating conditions using an in-house simulation tool. The analyzed cycles were first optimized by aiming at maximizing the net electrical power and then aiming at minimizing the specific capital cost. As a result, compared to traditional plants, we obtained that in the first case, the more complex sCO2 cycle configuration shows competitive performance, while in the second case, the simpler sCO2 cycle configuration has a lower specific cost for the same electrical power produced (with a difference of approximately −130 €/kW compared to the steam cycle). In general, while traditional technologies confirmed a good trade-off between performance and cost, supercritical CO2 cycles show attractive characteristics for applications requiring simplicity and compactness, guaranteeing in the meantime other technical advantages such as water-free operation.
ICME Computational Framework for Ceramic APS Coatings
Authors: Abdi Frank , Achanta Surekha , Baid Harsh , Harik Vasyl , Yaghmaie Reza , Morscher Gregory N. , Balint Daniel , Zawada Larry , Jefferson George 
Published: October 2022

Abstract
Integrated Computational Material Engineering (ICME) framework for Air Plasma Spray (APS) process for ceramic coatings is developed for optimizing multifunctional coatings and APS process for Thermal Barrier Coating (TBC) system. ICME simulations of APS process for TBC, the burner rig test and furnace test of TBC have been performed along with the test validation of ICME predictions for Yttria-stabilized-zirconia (YSZ) TBC with APS 8YSZ top coating with / NiCoCrAlY bond over Waspaloy substrate. ICME predictions for residual deflection of TBC due to thermal loads after APS process, burner rig test and furnace test are in close agreement with the test results. Both test and ICME predictions show the as-manufactured TBC specimens exhibit bending after APS process and bending after Burner Rig and Furnace testing. Finite element model for TBC specimens shows bending induced by APS process, its thermal gradients and residual thermal stress. Microscale thermal models for APS process, burner rig test and furnace test have been used to predict thermal processes, porosity and stresses. Rumpling analysis of TBC predicts rumpling amplitude due to thermal stresses and thermal oxidation growth (TGO) in TBC, thickness of TGO, bond stress during rumpling and stresses in TGO layer. Predictions for the thickness of TGO compares well with experimental data. Progressive damage analysis revealed that failure is due to tension and out of plane shear, delamination growth due to oxidation penetrating YSZ TBC from the bond.
Near Critical Point Testing and Performance Results of a sCO2 Compressor for a 10MWe Brayton Cycle
Authors: Pelton Robert , Bygrave Jon , Wygant Karl , Wilkes Jason , Revak Thomas , Kim Kilyoung 
Published: October 2022

Abstract
Development and commercial acceptance of sCO2 Brayton cycles for power generation applications are growing rapidly as they offer performance advantages over other cycles. To maximize the cycle performance, the compressors are designed to operate near the critical point of the working fluid. At the critical point the fluid properties change rapidly with variations in inlet conditions. This makes it challenging to both accurately predict the performance and guarantee the operability of the compressor, as the behavior is affected by these slight variations in inlet conditions. A full scale 1st stage main compressor for a 10MWe-Class recompression Brayton cycle was built and tested to validate performance and operability in this unique operating range.
The compressor was tested in a laboratory environment with additional instrumentation, beyond what is required by PTC-10, to minimize the uncertainty in the measured performance. Complete constant speed characteristics were collected at multiple supercritical points, operating at constant inlet conditions for each speed line covering a range of compressor inlet densities from 400 to 600 kg/m3. Variations in the compressor stage efficiency and choke margin were observed, and the overall operability and stability of the compressor in response to changes in operating condition were also monitored. The compressor was shown to have excellent performance that closely matched the original design prediction. The performance at various inlet conditions showed minimal change in isentropic head coefficient at the design flow, but did show some variation in efficiency and choke margin across the map. These changes in performance were observed to be minimal, and did not affect the stable operation of the compressor. The results demonstrate that a commercial scale sCO2 compressor can operate near the critical point and achieve the high levels of performance and stability required for power generation applications.