bluuebunny/crossref_metadata_2025_split huggingface dataset:
Lateral Equilibrium Position Analysis Program With Applications to Electric Submersible Pumps
Authors: Norrbin Clay S. , Childs Dara W. 
Published: August 2017

The long length of sub-sea Electric Submersible Pumps (ESPs) requires a large amount of annular seals. Loading caused by gravity and housing curvature changes the Static Equilibrium Position (SEP) of the rotor in these seals. This analysis predicts the SEP due to gravity and/or well curvature loading. The analysis also interfaces displays the rotordynamics around the SEP.
A static and rotordynamic analysis is presented for a previously studied ESP model. This study differs by first finding the SEP and then performing a rotordynamic analysis about the SEP. Predictions are shown in a horizontal and a vertical orientation. In these two configurations, viscosities and clearances are varied through 4 cases: 1X 1cP, 3X 1cP, 1X 30cP, and 3X 30cP.
In a horizontal, straight-housing position, the model includes gravity and buoyancy on the shaft. At 1cP-1X and 1cP-3X, the horizontal statics show a moderate eccentricity ratio for the shaft with respect to the housing. With 30cP-1X, the predicted static eccentricity ratio is low at 0.08. With 30cP-3X, the predicted eccentricity ratio increases to 0.33.
Predictions for a vertical case of the same model are also presented. The curvature of the housing is varied in the Y-Z plane until rub or close-to-wall rub is expected. The curvature needed for a rub with a 1X 1cP fluid is 7.5 degrees of curvature. Curvature has little impact on stability. With both 1X 30cP and 3X 30cP, the maximum curvature for a static rub are over 25 degrees of curvature. Both 1X 30cP and 3X 30cP remain unstable with increasing curvature.
Experimental and Numerical Investigation of the Mutual Interaction Between Liner Film Cooling and Combustor Swirl Flow
Authors: Andreini Antonio , Becchi Riccardo , Facchini Bruno , Mazzei Lorenzo , Picchi Alessio , Vitale Ignazio , Tolpadi Anil 
Published: August 2017

In the continuous demand of increasing cooling efficiency for novel combustor liners, it is necessary to have a comprehensive understanding of the interaction of hot gases with coolant flows. The aim of the present study is the experimental characterization of the flow field and the measurement of liner heat transfer coefficient in a combustion chamber model equipped with an axial swirler and a liner slot cooling scheme.
The test rig geometry consists in a linear three sector chamber fed by an open loop blower. The system is operated at isothermal conditions. A highly swirled main stream flow is achieved by considering an injector geometries that produce flow structures which interact with film cooling flow delivered by a simplified slot at the inner wall of the liner. To study the effects of this mutual interaction, the flow field and the liner heat transfer are investigated at different slot cooling and injector flow rates.
A 2D PIV (Particle Image Velocimetry) technique is employed to investigate the test section flow field on two different planes. An experimental campaign focused on liner heat transfer measurement is carried out using a TLC (Thermochromic Liquid Crystals) steady state technique with a thin Inconel heating foil fed by two copper bus bars.
Results obtained indicate an appreciable role of film cooling flow on both swirler aerodynamics and the liner heat transfer coefficient. When the slot cooling flow rate is increased, the observed peak of heat transfer coefficient, due to liner-swirl flow interaction, gradually reduces. This is a consequence of a reduction in swirling jet expansion when slot cooling is increased, which also affects the amount of flow recirculation due to vortex breakdown.
Numerical Research on Effects of Shroud Contraction on Tip Leakage Flow and Overall Performance of Axial Compressors
Authors: Zhang Yufan , Li Jiabin , Ji Lucheng 
Published: August 2017

In the design of an axial compressor, many designers take advantage of this technology and employ contracted shroud. What is its impact on tip leakage flow and overall performance of the axial compressor? What is its mechanism? In this paper, the NASA Rotor67 is taken as a research case, and parameterized study is conducted to investigate the effects of shrouds with different inclined angles. The inclined angles range from 0° to 13°. Based on the above described plan, numerical simulations are conducted to the original rotor67 and its modified versions with inclined shroud. To remove factors that might interfere the results, original Rotor 67 and all the blades with modified shroud should be compared to their optimal design status. Adjoint optimization is used to give the optimum blade corresponding to each shroud with different blade inclined angles.
Then adjoint optimization was used again to give the optimum meridional flowpath for all the cases with different shroud inclined angles. This provides a powerful tool to evaluate the accuracy of the aforementioned prediction. A detailed comparison is made between the original flowpath and the optimized ones.
Numerical results are analyzed in detail between original Rotor67 and its modified versions. The results show that the shroud inclined angle has an effect on the overall performance of the blade. It will also redistribute the velocity triangles and the chordwise distribution of aero load in the tip region. Hence it exerts great influence on the tip leakage flow field in the meantime. Shroud with suitable inclined angles can suppress the developing of leakage vortex , and the best-inclined angle for rotor 67 is found to be roughly 11°.
A Thermodynamic Model to Quantify the Impact of Cooling Improvements on Gas Turbine Efficiency
Authors: Uysal Selcuk Can , Liese Eric , Nix Andrew C. , Black James 
Published: August 2017

Cooling of turbine hot-gas-path components can increase engine efficiency, reduce emissions, and extend engine life. As cooling technologies evolved, numerous blade cooling geometries have been, and continue to be proposed by researchers and engine builders for internal and external blade and vane cooling. However, the impact of these improved cooling configurations on overall engine performance is the ultimate metric. There is no assurance that obtaining higher cooling performance for an individual cooling technique will result in better turbine performance because of the introduction of additional second law losses, e.g. exergy loss from blade heat transfer, cooling air friction losses, fluid mixing, etc. and thus the higher cooling performance might not always be the best solution to improve efficiency.
To quantify the effect of different internal and external blade cooling techniques and their combinations on engine performance, a cooled engine model has been developed for industrial gas turbines and aero-engines using MATLAB Simulink®. The model has the flexibility to be used for both engine types, and consists of uncooled on-design, turbomachinery design and a cooled off-design analysis in order to evaluate the engine performance parameters by using operating conditions, polytropic efficiencies, material information and cooling system information. The cooling analysis algorithm involves a Second Law analysis to calculate losses from the cooling technique applied.
The effects of variations in engine parameters such as turbine inlet temperature, by-pass ratio, and operating temperature are studied. The impact of variations in metal Biot number, thermal barrier coating Biot number, film cooling effectiveness, internal cooling effectiveness and maximum allowable blade temperature on engine performance parameters are analyzed. Possible design recommendations based on these variations, and direction of use of this tool for new cooling design validation, are presented.
Electrochemical Carbon Separation in a SOFC-MCFC Poly-Generation Plant With Near-Zero Emissions
Authors: Mastropasqua Luca , Campanari Stefano , Brouwer Jack 
Published: August 2017

High temperature fuel cells have been studied as a suitable solution for Carbon Capture and Storage (CCS) purposes at a large scale (>100 MW). However, their modularity and high efficiency at small-scale make them an interesting solution for Carbon Capture and Utilisation at the distributed generation scale when coupled to appropriate use of CO2 (i.e., for industrial uses, local production of chemicals etc.). These systems could be used within low carbon micro-grids to power small communities in which multiple power generating units of diverse nature supply multiple products such as electricity, cooling, heating and chemicals (i.e., hydrogen and CO2).
The present work explores fully electrochemical power systems capable of producing a highly pure CO2 stream and hydrogen. In particular, the proposed system is based upon integrating a Solid Oxide Fuel Cell (SOFC) with a Molten Carbonate Fuel Cell (MCFC). The use of these high temperature fuel cells has already been separately applied in the past for CCS applications. However, their combined use is yet unexplored. Moreover, both industry and US national laboratories have expressed their interest in this solution.
The reference configuration proposed envisions the direct supply of the SOFC anode outlet to a burner which, using the cathode depleted air outlet, completes the oxidation of the unconverted species. The outlet of the burner is then fed to the MCFC cathode inlet which separates the CO2 from the stream. Both the SOFC and MCFC anode inlets are supplied with pre-reformed and desulfurized natural gas. The MCFC anode outlet, which is characterised by a high concentration of CO2, is fed to a CO2 separation line in which a two-stage Water Gas Shift (WGS) reactor and a PSA/membrane system respectively convert the remaining CO into H2 and remove the H2 from the exhaust stream. This has the significant advantage of achieving the required CO2 purity for liquefaction and long-range transportation without requiring the need of cryogenic or distillation plants. Moreover, the highly pure H2 stream can either be sold as transportation fuel or a valuable chemical.
Furthermore, different configurations are considered with the final aim of increasing the Carbon Capture Ratio (CCR) and maximising the electrical efficiency. Moreover, the optimal power ratio between SOFC and MCFC stacks is also explored.
Complete simulation results are presented, discussing the proposed plant mass and energy balances and showing the most attractive configurations from the point of view of total efficiency and CCR.
Analysis of the Influence of Geometric Structure on the Rotationally Induced Ingress
Authors: Zhenxia Liu , Jun Ma , Jianping Hu , Lifen Zhang 
Published: August 2017

Rotating air inside the wheel-space creates a radial gradient of pressure which drives the gas ingress through the rim seal. This kind of reason for the gas ingestion is called rotationally induced ingress (RI). The minimum sealing flow rate was proportional to the seal-clearance. The geometric structure, including the position of the seal-clearance, is also important to predict the minimum sealing flow rate for RI ingestion. This paper gets the sealing efficiency and the flow results of different geometric structure through the method of 3D steady compressible CFD (Computational Fluid Dynamics). Because the analysis of the influence of geometry is given under the condition of RI ingestion, a 3D model without turbine blades has been chosen.
Some experiments initially revealed that the different seal-clearance positions have different sealing efficiency. However, what position would have best sealing efficiency was not given. If the position of seal-clearance is selected in the rotor disc or the static disc, the effect of the “pump” of the rotor disc is more obvious, which makes the gas ingestion serious. When the position of seal-clearance is near the rotor disc, the gas is fully mixed with the cooling air after the ingestion and then flows to the side of the static disc. Therefore, the sealing efficiency of the structure, whose seal-clearance position is near the rotor disc, will be higher than that, whose seal-clearance position is close to the static disc. When the fluid flows to the static disc, the velocity triangle shows that a barrier will be created between the cavity and mainstream in a particular seal-clearance position, which makes the efficiency higher than other positions.
Heat and Mass Transfer Characteristics of Water Droplets in Wet Compression Process
Authors: Liu Chunlei , Li Xiang , Zhang Hai , Zheng Qun 
Published: August 2017

Wet compression technology is an economic and effective approach to improve the performance of gas turbine. In the process of wet compression, the gas turbine engine will ingest a certain amount of water, which can influence the overall performance of the engine. Thermodynamic process and performance of compressor are influenced significantly by heat and mass transfer of the injected water droplets.
This study is a new research of investigating theoretically the water droplets effects on the heat and mass transfer characteristics. It focuses on the aerodynamic and thermodynamic effects of the two-phase flow in the compressor stage. The application of Computational Fluid Dynamics (CFD) is the basic method to examine the details of the flow in an axial compressor stage and how it is affected by the presence of water, especially by the water droplets. The computation of water droplets characteristics, are provided by a simulation model of the code named CFX. Considering the change in aerodynamics and thermodynamics feature due to the water droplets, the compressor stage’s performance variations are analyzed. The movement and the evaporation of the water droplets in a compressor stage are simulated and analyzed by using unsteady numerical methods under different water injecting conditions in this paper. The movement characteristics of water droplets in compressor passage are investigated to understand the flow mechanisms responsible for wet compression formation process.
The investigation of water droplets in compression can help to understand some phenomenons by using wet compression technology. The flow of water droplets between rotor blades are analyzed by using computational fluid dynamics method. Full coupling between gas and water droplets are adopted, allowing gas and water droplets to affect each other. Many motion parameters of water droplets are researched, such as slip velocity, Weber number and Reynolds number. The forces acting on water droplet are also discussed. Aerodynamic breakup of water droplets and interactions between water droplets and wall are taken into consideration at the same time.
The results indicate that: (1) The motion of water droplets in compression areor mainly controlled by drag force. The motion parameters of water droplets changes mostly at the entrance of flow passage between rotor blades, and the turbulence intensity and breakup strength of water droplets reaches their maximum at the entrance. (2) The flow angle of water droplets is bigger than gas in rotor region due to their inertia, which can explain why water droplets have bigger separation degree and are easier to flow toward blade pressure surface. (3) The motion of water droplets in stator region is also important to be investigated for wet compression, and the motion analysis of single water droplets between blades is still needed to be developed, so more investigation will be carried out.
An Integral Type µ Synthesis Method for Temperature and Pressure Control of Flight Environment Simulation Volume
Authors: Zhu Meiyin , Wang Xi 
Published: August 2017

Flight Environment Simulation Volume (FESV) is the most important part of Altitude Ground Test Facilities (AGTF). It’s temperature and pressure control precision determines the level of test ability of AGTF. Therefore, in order to study the temperature and pressure control problem of FESV and improve the modeling precision of FESV, the energy equation and gas state equation are used to deduce the temperature and pressure differential equations of FESV. Meanwhile, the heat transfer influence of FESV has been taken into account in this paper and the transient heat conduction of FESV is established by using a discretizing method. The temperature and pressure differential equations of FESV are linearized around a balance point and the uncertainty of actuators has been considered in multiplicative uncertainty. The augmented system of linear model of FESV and the actuators are obtained. For the sake of making the controller design and weighting function choice more easily, a normalization method is used to normalize the augmented system. For the purpose of achieving the temperature and pressure synchronic control of FESV, a two-degree-of-freedom integral type μ synthesis control design method is proposed. What’s more, for guaranteeing the designed μ synthesis controller has servo tracking and disturbance attenuation performance, the performance weighting functions are designed according to the frequency division weighting principle and the control weighting functions are designed by using the principle of low frequency free limit, medium frequency gradually increase the limit, and high frequency maximum limit. The MATLAB Robust Control Toolbox function dksyn is used to design the μ controller.
In order to verify the effectiveness of designed μ controller, we assume two types of engine test conditions. The simulation results show, for the engine test condition one, the biggest relative tracking error of temperature is less than 0.5% and the relative steady state error of pressure is less than 0.1% and the relative tracking error of pressure slope signal is less than 3%. For the engine test condition two, the relative steady state error of temperature is less than 0.1% and the relative tracking error of temperature slope signal is less than 1%. To verify the advantage of designed μ controller, we designed a PID controller and compared the simulation results with μ controller. The comparison results showed that the designed μ controller provided better performance than the PID controller.
A Physics-Based Dynamic Model for Boilers: Part 2 — Model Reduction in a Cogeneration Application
Authors: Blom Matthew J. , Brear Michael J. , Manzie Chris G. , Wiese Ashley P. 
Published: August 2017

This paper is the second part of a two part study that develops, validates and integrates a one-dimensional, physics-based, dynamic boiler model. Part 1 of this study [1] extended and validated a particular modelling framework to boilers. This paper uses this framework to first present a higher order model of a gas turbine based cogeneration plant. The significant dynamics of the cogeneration system are then identified, corresponding to states in the gas path, the steam path, the gas turbine shaft, gas turbine wall temperatures and boiler wall temperatures. A model reduction process based on time scale separation and singular perturbation theory is then demonstrated.
Three candidate reduced order models are identified using this model reduction process, and the simplest, acceptable dynamic model of this integrated plant is found to require retention of both the gas turbine and boiler wall temperature dynamics. Subsequent analysis of computation times for the original physics-based one-dimensional model and the candidate, reduced order models demonstrates that significantly faster than real time simulation is possible in all cases. Furthermore, with systematic replacement of the algebraic states with feedforward maps in the reduced order models, further computational savings of up to one order of magnitude can be achieved. This combination of model fidelity and computational tractability suggest suggests that the resulting reduced order models may be suitable for use in model based control of cogeneration plants.
Quantitative CFD Analyses of Particle Deposition in a Heavy-Duty Subsonic Axial Compressor
Authors: Aldi Nicola , Casari Nicola , Dainese Devid , Morini Mirko , Pinelli Michele , Spina Pier Ruggero , Suman Alessio 
Published: August 2017

Solid particle ingestion is one of the principal degradation mechanisms in the compressor and turbine sections of gas turbines. In particular, in industrial applications, the micro-particles not captured by the air filtration system can cause deposits on blading and, consequently, result in a decrease in compressor performance.
In literature there are some studies related to the fouling phenomena in transonic compressors, but in industrial applications (heavy-duty compressors, pump stations, etc.) the subsonic compressors are widespread. It is highly important for the manufacturer to gather information about the fouling phenomenon related to this type of compressor.
This paper presents three-dimensional numerical simulations of the micro-particle ingestion (0.15 μm – 1.50 μm) in a multistage (i.e. eight stage) subsonic axial compressor, carried out by means of a commercial computational fluid dynamic code. Particles of this size can follow the main air flow with relatively little slip, while being impacted by flow turbulence. It is of great interest to the industry to determine which zones of the compressor blades are impacted by these small particles. Particle trajectory simulations use a stochastic Lagrangian tracking method that solves the equations of motion separately from the continuous phase.
The adopted computational strategy allows the evaluation of particle deposition in a multistage axial compressor thanks to the use of a mixing plane approach to model the rotor/stator interaction. The compressor numerical model and the discrete phase model are set up and validated against the experimental and numerical data available in literature.
The number of particles and sizes are specified in order to perform a quantitative analysis of the particle impacts on the blade surface. The blade zones affected by particle impacts and the kinematic characteristics (velocity and angle) of the impact of micrometric and sub-micrometric particles with the blade surface are shown. Both blade zones affected by particle impact and deposition are analyzed.
The particle deposition is established by using the quantity called sticking probability, adopted from literature. The sticking probability links the kinematic characteristics of particle impact on the blade with the fouling phenomenon.
The results show that micro-particles tend to follow the flow by impacting on the compressor blades at full span. The suction side of the blade is only affected by the impacts of the smallest particles. Particular fluid dynamic phenomena, such as corner separations and clearance vortices, strongly influence the impact location of the particles.
The impact and deposition trends decrease according to the stages. The front stages appear more affected by particle impact and deposition than the rear ones.
Prediction of Stress Relaxation in Power Plant Components Based on a Constitutive Model
Authors: Kostenko Y. , Naumenko K. 
Published: August 2017

Many power plant components and joint connections are subjected to complex thermo-mechanical loading paths under severe temperature environments over a long period. An important part in the lifetime assessment is the reliable prediction of stress relaxation using improved creep modeling to avoid possible integrity or functionality issues and malfunction in such components.
The aim of this work is to analyze the proposed constitutive model for advanced high chromium steels with the goal of predicting stress relaxation over the long term. The evolution equations of the constitutive model for inelastic material behavior are introduced to account for hardening and softening phenomena. The material properties were identified for 9–12%CrMoV steels in the creep range.
The model is applied to the stress relaxation analysis of power plant components. The results for long-term assessment, which are encouragingly close to reality, will be presented and discussed. An outlook on further developments of the model and assessment procedure is also provided.