bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design of a Cooled sCO2 Combustion Test Rig for Steady-State Kinetics Testing
Authors: Katcher Kelsi M. , Allison Timothy C. , Marshall Michael , Jin Yuin , Lim Chansun , Chang Sungho 
Published: September 2021

Abstract
Within the research area of sCO2 power cycles, the direct-fired oxy-combustion cycle is of great interest because the inherent carbon capture makes it a desirable option for clean power generation. In order to better understand the combustion kinetics of the direct-fired cycle in sCO2, a laboratory-scale combustion test rig was designed. The design and thermal-mechanical analysis of the combustor test rig for steady-state open-loop combustion testing is presented. The test rig is designed for operating conditions of 265 bar and full-scale oxy-combustion temperatures. The test rig incorporates a laser igniter and modular fully premixed injector to enable testing with step- or swirl-style flame holders. The rig also employs an existing dense-phase sCO2 pump to provide a closed-loop high-flow cooling circuit to enable cost-effective short-lead manufacturing of liner and pressure casing components. Finally, the test rig’s multi-zone copper alloy C18150 liner design minimizes thermal stresses and allows for independent control of dilution flow in each zone to vary combustion temperatures. Planned measurements include exit temperature profile and chamber dynamic pressures. The sensitivity of CO oxidation and other reaction rates to temperature will be indirectly evaluated using post-combustion gas sampling for comparison with combustion simulations.
Assessment of Non-Standard Procedure in Field Testing of Gas Turbine Driven Centrifugal Compressors
Authors: Casari Nicola , Fadiga Ettore , Pinelli Michele , Suman Alessio , Kurz Rainer , Davis Kevin C. , Marin Flavio 
Published: September 2021

Abstract
Gas turbine driven centrifugal compressors often undergo a detailed performance analysis either for the acceptance by the user or to evaluate their existing condition. Often, the tests are conducted at site, where the compressor and its driver must prove their capability to fulfill the requirements of the project specifications. Typical field testing of gas turbine compressor packages requires the evaluation of head, efficiency, capacity, fuel consumption, as well as the available driver power. The process is not straightforward since the conditions at which the compressor package is tested are typically different from the originally agreed upon conditions. In particular, the ambient conditions, as well as the load conditions at the test are usually different. There are a number of standard procedures for carrying out a field test. In this work, one of them is considered for quantifying how the variation in some parameters can impact the result of the field test. Particular attention is given to the evaluation and data correction for the gas turbine. The results of the test can be affected by several factors. Some of them are related to the installation, such as the array of RTDs used. Further, the influence of the accuracy of the input data that are used for the calculations must be considered by determining the effect of test uncertainty. Other parameters that can affect the results are related to the modeling: The natural gas exhibits real gas behavior at the test conditions, and an equation of state has to be used for data conversion. The choice of an equation of state can translate into a differences in the test results. An assessment of the impact of these factors on the outcome of a field test is reported. From the results of this work, the expected error as consequence of deviation from the specification can be quantified.
Design and Validation of a Novel Test-Rig for RQL Flame Dynamics Studies
Authors: March Martin , Renner Julian , Hirsch Christoph , Sattelmayer Thomas 
Published: September 2021

Abstract
In this paper a novel test-rig for the investigation of low-frequency thermoacoustic instabilities in aero-engines with air-staging RQL (rich-quench-lean) is presented. The new approach is to separate the rich primary zone from the lean secondary zone to allow for an isolated thermoacoustic characterization of each combustion zone. In addition the test-rig offers the possibility to combine both zones to judge the transferability of the findings from the separated to the compact configuration. The high modularity of the test-rig is already considered in the design-phase and allows a cost and time efficient manufacturing. Heat losses in the primary zone and the transition duct between the two zones play a crucial role for the functionality of the facility and are estimated during design to guarantee a stable re-ignition in the secondary zone. The main design steps in the secondary zone for achieving complete burn-out of the hot primary combustion gases are described. The realization of the acoustic excitation via loudspeakers is described and damping measures to improve combustor stability are explained. The operation of both zones, their acoustic behavior and the operational limits of the test-rig are demonstrated experimentally. They include first thermoacoustic measurement data of naturally occurring instabilities, the corresponding eigenfrequencies and the validation of the test-rig design. Finally an outlook on the future work in the research project concludes this paper.
On the Experimental Dynamic Force Performance of a Squeeze Film Damper Supplied Through a Check Valve and Sealed With O-Rings
Authors: San Andrés Luis , Rodríguez Bryan 
Published: September 2021

Abstract
In rotor-bearing systems, squeeze film dampers (SFDs) assist to reduce vibration amplitudes while traversing a critical speed and also offer a means to suppress rotor instabilities. Along with an elastic support element, SFDs are effective means to isolate a rotor from its casing. O-rings (ORs), piston rings (PRs) and side plates as end seals reduce leakage and air ingestion while amplifying the viscous damping in configurations with limited physical space. ORs also add a centering stiffness and damping to a SFD. The paper presents experiments to quantify the dynamic forced response of an O-rings sealed ends SFD (OR-SFD) lubricated with ISO VG2 oil supplied at a low pressure (0.7 bar(g)). The damper is 127 mm in diameter (D), short in axial length L = 0.2D, and the film clearance c = 0.279 mm. The lubricant flows into the film land through a mechanical check valve and exits through a single port. Upstream of the check valve, a large plenum filled with oil serves to attenuate dynamic pressure disturbances. Multiple sets of single-frequency dynamic loads, 10 Hz to 120 Hz, produce circular centered orbits with amplitudes r = 0.1c, 0.15c and 0.2c. The experimental results identify the test rig structure, ORs and SFD force coefficients; namely stiffness (K), mass (M) and viscous damping (C). The ORs coefficients are frequency independent and show a sizeable direct stiffness, KOR ∼ 50% of the test rig structure stiffness, along with a quadrature stiffness, K0∼0.26 KOR, demonstrative of material damping. The lubricated system damping coefficient equals CL = (CSFD + COR); the ORs contributing 10% to the total. The experimental SFD damping and inertia coefficients are large in physical magnitude; CSFD slightly grows with orbit size whereas MSFD is relatively constant. The added mass (MSFD) is approximately four-fold the bearing cartridge mass; hence, the test rig natural frequency drops by ∼50% once lubricated. A computational physics model predicts force coefficients that are just 10% lower than those estimated from experiments. The amplitude of measured dynamic pressures upstream of the plenum increases with excitation frequency. Unsuspectedly, during dynamic load operation, the check valve did allow for lubricant backflow into the plenum. Post-tests verification demonstrates that, under static pressure conditions, the check valve does work since it allows fluid flow in just one direction.
Reconstruction of a Steam Turbine Blade Using Piecewise Bernstein Polynomials and Transfinite Interpolation
Authors: Pérez Rubio Luis David , Galván González Sergio Ricardo , Domínguez Mota Francisco Javier , Cerriteño Sánchez Angel , Tamayo Soto Miguel Angel , Delgado Sánchez Giovanni 
Published: September 2021

Abstract
Turbine blades are designed to achieve its maximum efficiency, but deformations caused by the exposition to extreme operating environments provokes reduction in the engine performance. Often, operators choose to repair a damaged blade instead of replacing it to save money, however, reconstructing its virtual model, commonly the first step in the repairing process, can be challenging due to the geometrical complexity of the blades, variability in deformations and the requirement to meet the dimensions specified by the manufacturer. This paper presents the reconstruction methodology of the clean virtual model of a steam turbine blade through numerical tools, as a previous step for regenerating a worn blade. First, few cross-sectional airfoil profiles are extracted from the damaged blade and are regenerated using Bernstein polynomials; then, using the previously obtained data, many more profiles are interpolated and stacked along the spanwise direction of the blade via Transfinite Interpolation in order to obtain a smooth and continuous representation of the reference blade. Final deviation between the reference and reconstructed model resulted in an average value of 1.5496 × 10−3 % and 9.685 × 10−5 % relative to the rotor diameter in the pressure and suction sides respectively, showing an accuracy that could be considered to be used in industrial applications or optimization.
On the Effect of Noise Induced Dynamics on Linear Growth Rates of Oscillations in an Electroacoustic Rijke Tube Simulator
Authors: Vishnoi Neha , Wahi Pankaj , Saurabh Aditya , Kabiraj Lipika 
Published: September 2021

Abstract
Suppressing self-excited thermoacoustic oscillations in combustion chambers is essential for gas turbine system stability. Passive acoustic damping devices such as Helmholtz resonators are commonly employed in modern combustors to address the problem of thermoacoustic instabilities. The estimation of deterministic parameters characterizing flame-acoustic coupling, specifically the stability margins and linear growth/decay rates, is a prerequisite for designing these devices. As gas turbine combustors are typically noisy systems due to the presence of highly turbulent flows and unsteady combustion, it is essential to understand the role of noise and its impact on the estimated system stability. Recently several new results on the stochastic dynamics of thermoacoustic systems and the use of noise-induced dynamics to estimate system stability characteristics have been reported. In the present work, we study the different approaches previously reported on the estimation of linear growth/decay rates from noise-induced dynamics on an electroacoustic Rijke tube (a prototypical thermoacoustic system) simulator. We estimate the growth rates from noisy data obtained from the subthreshold, bistable, and linearly-unstable regions of the observed subcritical Hopf bifurcation and investigate the effect of additive noise intensity. We find that the noise intensity affects the stability boundaries and the estimated growth rates.
Noise Reduction Analysis of Electronic Device Cooling Fan With Duct and Its Application Under Variable Working Conditions
Authors: Sun Zonghan , Tian Jie , Liśkiewicz Grzegorz , Du Zhaohui , Ouyang Hua 
Published: September 2021

Abstract
A noise reduction method for axial flow fans using a short inlet duct is proposed. The pattern of noise reduction imposed by the short inlet duct on the axial flow cooling fan under variable working conditions was experimentally and numerically examined. A 2-cm inlet duct was found to reduce tonal noise. As the tip Mach number of the fan increased from 0.049 to 0.156, the reduction in the total average sound pressure level at 1 m from the fan increased from 0.8 dB(A) to 4.3 dB(A), and further achieved 4.8 dB(A) when a 1-cm inlet duct was used. The steady computational fluid dynamics (CFD) showed that the inlet duct has little effect on the aerodynamic performance of the fan. The results of the full passage unsteady calculation at the maximum flow rate showed that the duct has a significant influence on the suction vortexes caused by the inlet flow non-uniformity. The suction vortexes move upstream to weaken the interaction with the rotor blades, which significantly reduces the pulsating pressure on the blades. The sound pressure level (SPL) at the blade passing frequency (BPF) contributed by the thrust force was calculated to reduce by 36 dB at a 135° observer angle, reflecting the rectification effect of the duct on the non-uniform inlet flow and the improvement in characteristics of the noise source. The proper orthogonal decomposition (POD) of the static pressure field on the blades verified that the main spatial mode is more uniformly distributed due to the duct, and energy owing to the rotor-inlet interaction decreases. A speed regulation strategy for the cooling fan with short inlet duct is proposed, which provides guidance for the application of this noise reduction method.
Reduced-Order Modeling of Extreme Speed Turbochargers
Authors: Fellows David W. , Bodony Daniel J. , McGowan Ryan C. 
Published: September 2021

Abstract
In order to improve their efficiency and performance, aircraft intermittent combustion engines often incorporate turbochargers that are adapted from ground-based applications. These turbochargers experience conditions outside of their design operating envelope and are found to experience high-cycle fatigue brought on by aerodynamically-induced blade resonances. The onset of fluid-structural interactions, such as flutter and forced response, in turbochargers at these conditions has not been extensively studied. A reduced-order model of the aeroelastic response of the turbine is developed using the Euler-Lagrange equation informed by numerical data from uncoupled computational fluid dynamic (CFD) and computational structural dynamic (CSD) calculations. The structural response of the reduced-order model is derived from a method of assumed modes approach. The unsteady fluid response is described by a modified version of piston theory as a first step towards including inhomogeneous aerodynamic forcing. Details of the reduced order model are given. The capability of the reduced-order model to predict the presence of flutter from a subset of the uncoupled numerical simulation data is discussed.
A Discussion: Issue Improving the Accuracy of Turbine Blade Heat Transfer Simulation
Authors: Zhang Shenghui , Ding Shuiting , Liu Chuankai , Zhao Gang , Wang Jie 
Published: September 2021

Abstract
To be able to set uniform inlet boundary conditions in simulation, there must be an inlet extension at the first guide vane. In the inlet extension, turbulence experiences strong numerical dissipation, which has not been paid attention to. In the current paper, the influence of the numerical dissipation of turbulence on accuracy in predicting heat transfer was discussed. Two cases, where the numerical dissipation of turbulence was neglected, were analysed. In the first case, wrong conclusion about effect of turbulence scale on heat transfer was drawn: blade heat transfer increases with inlet turbulence scale under the same inlet turbulence intensity. The mechanism for the wrong conclusion is that turbulence with larger scale numerically dissipates more slowly in the inlet extension so that turbulence intensity at blade leading edge is greater under turbulence with larger scale, it is the turbulence intensity not turbulence scale itself really affects heat transfer. In the second case, when the numerical dissipation of turbulence is neglected and turbulence parameters at measuring plane of inlet are directly as input for turbulence boundary condition, flow transition is postponed downstream and heat transfer error is greater, however, when the numerical dissipation of turbulence is considered and turbulence parameters at measuring plane are regard as benchmark and matched by adjusting parameters of inlet turbulence boundary condition, the result shows better agreement with experiment. Thus, the correct way to set turbulence boundary condition is to match turbulence parameters at measuring plane by adjusting parameters of inlet turbulence boundary.
Experimental Study on Lean Blowout Limits of Turbulent Premixed Hydrogen/Ammonia/Air Mixtures
Authors: Goldmann Andreas , Dinkelacker Friedrich 
Published: September 2021

Abstract
As the demand for greenhouse gas neutral transportation and power generation solutions is growing, alternative carbon-free fuel such as hydrogen (H2) and ammonia (NH3) are gaining more attention. Mixtures of both fuels allow the adjustment of combustion properties. With future fuels also the vision of very clean combustion can be taken into the focus, being for instance based on lean premixed and for liquid fuels prevaporized combustion for gas turbines. For the utilization of such concepts, however, flame stability is essential. In this study the upper stability limits, i.e. lean blowout of turbulent hydrogen/ammonia/air flames, is experimentally investigated in a generic non-swirl premixed burner at atmospheric conditions. Special focus is laid on a measurement setup with fully automatized measurement procedure, to reach the stability limits, as these limits tend to depend for instance on the approach speed towards the limit. The ammonia content was varied from 0 vol% to 50 vol% in 10 vol% steps with the rest being hydrogen, for a broad range of fuel-air-equivalence ratios. The lean blowout limit is increasing almost linearly with increasing fuel-air-equivalence ratios, whereas with increasing ammonia content the limit is decreasing. Furthermore, a model for the lean blowout limits were derived, which is able to predict the acquired experimental data with high accuracy.
Impact of Plant Siting on Performance and Economics of Indirect Supercritical CO2 Coal Fired Power Plants
Authors: Pidaparti Sandeep R. , White Charles W. , Weiland Nathan T. 
Published: September 2021

Abstract
Indirect-fired supercritical CO2 (sCO2) power cycles are being explored as an attractive alternative to steam Rankine cycles for a variety of heat sources including fossil, concentrated solar power (CSP), nuclear, waste heat, etc. Due to the near-ambient CO2 critical temperature of 31°C, the effects of ambient temperature on sCO2 power cycles performance are expected to be more significant than for steam Rankine cycles.
This study presents the impact of plant siting on the performance and economics of coal-fired utility scale power plants based on indirect sCO2 power cycles with carbon capture and storage (CCS). Four different plant sites across the United States have been selected for investigation: Chicago, IL; Kemmerer, WY; Houston, TX; Knoxville, TN. For each plant site, local parameters such as design ambient conditions, coal type and prices, captured CO2 transportation and storage (T&S) costs are considered for the techno-economic analyses (TEA). To determine the optimum plant design for each location, two power cycle configurations (recompression cycle, partial cooling cycle with reheat) and two cooling technologies (dry and adiabatic cooling) are examined. The optimization was conducted using automated derivative-free optimization (DFO) algorithms available under NETL’s Framework for Optimization and Quantification of Uncertainty and Sensitivity (FOQUS) platform. The optimization design variables include parameters such as turbine inlet temperatures and pressure, sCO2 cooler outlet temperatures, recuperators approach temperature and pressure drop etc. The study demonstrates the variability in optimal plant design for different ambient and fuel input conditions. The results will be used in future sCO2 technology market analyses.
AI Assisted High Fidelity Multi-Physics Digital Twin of Industrial Gas Turbines
Authors: Krishnababu Senthil , Valero Omar , Wells Roger 
Published: September 2021

Abstract
Data driven technologies are revolutionising the engineering sector by providing new ways of performing day to day tasks through the life cycle of a product as it progresses through manufacture, to build, qualification test, field operation and maintenance. Significant increase in data transfer speeds combined with cost effective data storage, and ever-increasing computational power provide the building blocks that enable companies to adopt data driven technologies such as data analytics, IOT and machine learning. Improved business operational efficiency and more responsive customer support provide the incentives for business investment. Digital twins, that leverages these technologies in their various forms to converge physics and data driven models, are therefore being widely adopted.
A high-fidelity multi-physics digital twin, HFDT, that digitally replicates a gas turbine as it is built based on part and build data using advanced component and assembly models is introduced. The HFDT, among other benefits enables data driven assessments to be carried out during manufacture and assembly for each turbine allowing these processes to be optimised and the impact of variability or process change to be readily evaluated. On delivery of the turbine and its associated HFDT to the service support team the HFDT supports the evaluation of in-service performance deteriorations, the impact of field interventions and repair and the changes in operating characteristics resulting from overhaul and turbine upgrade. Thus, creating a cradle to grave physics and data driven twin of the gas turbine asset.
In this paper, one branch of HFDT using a power turbine module is firstly presented. This involves simultaneous modelling of gas path and solid using high fidelity CFD and FEA which converts the cold geometry to hot running conditions to assess the impact of various manufacturing and build variabilities. It is shown this process can be executed within reasonable time frames enabling creation of HFDT for each turbine during manufacture and assembly and for this to be transferred to the service team for deployment during field operations.
Following this, it is shown how data driven technologies are used in conjunction with the HFDT to improve predictions of engine performance from early build information. The example shown, shows how a higher degree of confidence is achieved through the development of an artificial neural network of the compressor tip gap feature and its effect on overall compressor efficiency.
Understanding the Dynamics of Critical Transitions in a Contra-Rotating Fan
Authors: Madasseri Payyappalli Manas , Pradeep A. M. 
Published: September 2021

Abstract
In this experimental study, we investigate the fundamental behaviour of a low speed contra-rotating fan and describes the reasons leading to the instabilities in the fan at low mass flow rates. A contra-rotating fan is a possible alternative to conventional fans and has potential aerodynamic advantages. This study identifies certain features that are unique to a contra-rotating configuration. Rotor-1 and rotor-2 behaves differently at low mass flow rates. Though rotor-1 is stable up to low mass flow rates, rotor-2 enters into an unstable mode of operation at mass flow rates close to the design mass flow rate. The critical region where the instability arise in rotor-1 is its tip and in rotor-2 is its hub. The instability is also found to change the structure as it propagates along the annulus. It is identified that the presence of rotor-2 downstream of rotor-1 under-loads rotor-1 and thus significantly affects the loading on rotor-1. The instability arises due to the tip-leakage vortex at high frequencies and due to modal waves at low frequencies. The study thus identifies the major regions of the rotors which are the sources of instabilities and also identifies the process of transition to instability in the contra-rotating fan.