bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and Manufacturing of a Metal 3D Printed kW Scale Axial Turboexpander
Authors: Novotny Vaclav , Vitvarova Monika , Kolovratnik Michal , Stunova Barbora Bryksi , Vodicka Vaclav , Spale Jan , Zikmund Petr , Drasnar Martin , Schastlivtseva Elizaveta 
Published: November 2019

Abstract
Greater expansion of distributed power and process systems based on thermodynamic cycles with single to hundred kW scale power output is limited mainly there are not available cost-effective expanders.
Turboexpanders have a perspective of high efficiency and flexibility concerning operating parameters even for the micro applications. However, they suffer from a high manufacturing cost and lead time in the development of traditional technologies (such as casting and machining processes).
Additive manufacturing provides a possibility to overcome some of the issues. Manufacturing parts with complicated shapes by this technology, combining multiple components into a single part or rapid production by 3D printing for development purposes are among the prospective features with this potential. On the other hand, the 3D printing processes come with certain limitations which need to be overcome.
This paper shows a design and manufacturing process of a 3 kW axial impulse air turbine working with isenthalpic drop 30 kJ/kg. Several samples to verify printing options and the turbine itself has been manufactured from stainless steel by the DMLS additive manufacturing method. Manufactured are two turbine variations regarding blade size and 3D printer settings while maintaining their specific dimensions. The turboexpanders testing method and rig is outlined. As the surface quality is an issue, several methods of post-processing of 3D printed stator and rotor blading to modify surface quality are suggested. Detailed experimental investigation is however subject of future work.
A Study on the Leakage and Rotordynamic Coefficients of a Long-Smooth Seal With Laminar-Two-Phase, Mainly-Oil Mixtures
Authors: Zhang Min , Childs Dara W. , Tran Dung L. , Shrestha Hari 
Published: November 2019

Abstract
This paper conducts a comprehensive study on the effects of the air presence in the oil on the leakage and rotordynamic coefficients of a long-smooth seal (inner diameter D = 89.306 mm, radial clearance Cr = 0.140 mm, and length-diameter ratio L/D = 0.65) under laminar-two-phase flow conditions. The mixture consists of air and silicone oil with inlet GVF (gas volume fraction) up to 10%.
Tests are performed at inlet temperature Ti = 39.4 °C, exit pressure Pe = 6.9 bars, pressure drop PD = 31 and 37.9 bars, and rotor speed ω = 5, 7.5, and 10 krpm. The test seal is always concentric with the rotor, and no intentional fluid pre-rotation is provided at the seal inlet.
The complex dynamic stiffness coefficients Hij of the test seal are measured and fitted by the frequency-independent direct stiffness K, cross-coupled stiffness k, direct damping C, cross-coupled damping c, direct virtual-mass M, and cross-coupled virtual-mass mq coefficients.
Under laminar flow conditions, increasing inlet GVF has negligible effects on K, k, C, and effective damping Ceff, while it decreases c and M. These trends are correctly predicted by San Andrés’s bulk-flow model with laminar flow friction formula. As inlet GVF increases, measured leakage flow rate ṁ increases slightly. In general, the predictions of K, k, C, c, Ceff, and ṁ are reasonably close to measurements.
Influence of Temperature Distribution on Radial Growth of Compressor Discs
Authors: Luberti Dario , Tang Hui , Scobie James A. , Pountney Oliver J. , Owen J. Michael , Lock Gary D. 
Published: November 2019

Abstract
For the next generation of aero-engines, manufacturers are planning to increase the overall compressor pressure ratio from existing values around 50:1 to values of 70:1. The requirement to control the tight clearances between the blade tips and the casing over all engine-operating conditions is a challenge for the engine designer attempting to minimise tip-clearances losses. Accurate prediction of the tip clearance requires an accurate prediction of the radial growth of the compressor rotor, which depends on the temperature distribution of the disc. The flow in the rotating cavities between adjacent discs is buoyancy-driven, which creates a conjugate heat transfer problem: the disc temperature depends on the radial distribution of Nusselt number, which in turn depends on the radial distribution of disc temperature.
This paper focuses on calculating the radial growth of a simplified compressor disc in isolation from the other components. Calculations were performed using one-dimensional (1D) theoretical and two-dimensional finite-element computations (2D FEA) for overall pressure ratios (OPR) of 50:1, 60:1 and 70:1. At each pressure ratio, calculations were conducted for five different temperature distributions; the distribution based on an experimentally-validated buoyancy model was used as the datum case, and results from this were compared with those from linear, quadratic, cubic and quartic power laws.
The results show that the assumed distribution of disc temperature has a significant effect on the calculated disc growth, whereas the pressure ratio has only a relatively small effect. The good agreement between the growth calculated by the 1D theoretical model and the FEA suggests that the 1D model should be useful for design purposes.
An Evidence Based Process Facilitating Engineering Education and Innovation in the Field of Turbomachinery
Authors: Otto Marcel , Kapat Jayanta S. , Phelps Robin , O’Neal Thomas , Gramatikas George 
Published: November 2019

Abstract
A confluence of disruptive trends in the energy industry is creating an imperative for providers as well as all companies throughout the value-chain to innovate. Due to the physical and intellectual proximity of universities to cutting edge technology development universities are at the epicenter for the next generation of energy innovation and innovators. However, through traditional disciplinary coursework and research activities, today’s engineering faculty and students do not gain the skills to be effective innovators and advance their inventions from the lab to the market. As a result, new methods of education and training is required to meet the energy innovation imperative.
The National Science Foundation Innovation Corps (I-Corps) program, which aims to develop critical innovator skills while aiding in the process of developing innovations that have potential to solve a market-based problems. The program is an intense workshop with the goal to develop a scalable business model around the invention by “getting out of the building” and conducting more than 100 interviews with potential customers and other key stakeholders to test hypotheses related to problems and value propositions. The evidence from those interviews is used to validate or invalidate hypotheses about the business model.
The present paper examines the I-Corps program as an evidence-based process to facilitate engineering education and innovation in the field of turbomachinery. Utilizing a case study approach, we analyze the experiences of PDCC Technologies, a university based startup trying to commercialize a high temperature material as a potential component of gas turbine engines. The journey through the program including key “aha” moments and lessons learned is retold based on the specific example. The paper concludes with a summary of value for students and faculty and remarks on the improvement of the engineering program itself.
Heat Transfer Coefficient Augmentation for a Shaped Film Cooling Hole at a Range of Compound Angles
Authors: Haydt Shane , Lynch Stephen 
Published: November 2019

Abstract
Shaped film cooling holes are used to efficiently deliver coolant to the surface of a gas turbine part to keep metal temperatures low. The ultimate goal of film cooling is to reduce the heat flux into a component, relative to a case with no coolant injection. This reduction in heat flux is primarily achieved via a lower driving temperature at the wall for convection, represented by the adiabatic effectiveness. Another important consideration, however, is how the disturbance to the flowfield and thermal field caused by the injection of coolant augments the heat transfer coefficient. The present study examines the spatially-resolved heat transfer coefficient augmentation for a shaped film cooling hole at a range of compound angles, using a constant heat flux foil and IR thermography. Results show that the heat transfer coefficient increases with compound angle and with blowing ratio. Due to the unique asymmetric flowfield of a compound angle hole, a significant amount of augmentation occurs to the side of the film cooling jet, where very little coolant is present. This causes local regions of increased heat flux, which is counter to the goal of film cooling. Heat transfer results are compared with adiabatic effectiveness and flowfield measurements from a previous study.
Advantages and Experience of Using SSS (Synchro-Self-Shifting) Clutches in Hybrid Propulsion Such As CODELOG or CODELAG Naval Marine Systems
Authors: Hendry Morgan L. , Bellamy Nicholas 
Published: November 2019

Abstract
Hybrid marine ship propulsion systems are currently being used, and many more are being considered worldwide, including for commercial ships as well as for navies worldwide. These hybrid propulsion systems offer extended ship range and potentially quiet operation with propulsion on propeller shaft line electric motors. When high power and / or speed may be required, the main engines or turbines can be quickly started, and propeller shaft line clutches provide quick and reliable transition from or back to the electric motors.
In the naval marine sector, several ship programs currently use “Combined Diesel Electric or Gas Turbine” (CODELOG) or “Combined Diesel Electric and Gas Turbine” (CODELAG) propulsion. Some utilize Synchronous Self-Shifting Clutches, and some utilize other types of non-automatic friction clutches. Many navies worldwide are considering this type of hybrid propulsion, but variations in machinery arrangements and components can result in significant differences in fuel efficiency, weight, space, first time cost, ship performance, and propulsion machinery lifecycle maintenance with associated cost.
Therefore, serious investigation of the alternatives early in the ship design phase is important and accessing the experience of these existing systems with these components is vital, before settling on a machinery arrangement and its components for a future ship program.
As the old cliché says, “The Devil is in the Details!” Like any system, the success, the reliability, and the ultimate capability often come down to design details and the components chosen. Naval ships are designed to operate, even when damaged or when control or oil supply systems fail. Simplicity and the ability to improvise is often the key to mission success or failure. Synchronous Self-Shifting Clutches, or SSS Clutches, have proven to be “fit and forget” in these propulsion systems, have performed without fail in battle conditions, and this paper will describe the systems, explore the alternatives for propulsion clutches, provide advantages and disadvantages, and will provide experience of SSS Clutches in hybrid propulsion systems.
Impact of Fuel Composition on Gas Turbine Engine Performance
Authors: Burnes Dan , Camou Alejandro 
Published: November 2019

Abstract
An industrial gas turbine can run on a wide variety of fuels to produce power. Depending on the fuel composition and resulting properties, specifically the hydrogen-carbon ratio, the available output power, operability, and emissions of the engine can vary significantly. This study is an examination of how different fuels can affect the output characteristics of Solar Turbines Incorporated industrial engines, and highlights the benefits of using fuels with higher hydrogen-carbon ratios including higher power, higher efficiency, and lower carbon emissions. This study also highlights critical combustion operability issues that need to be considered such as autoignition, flashback, blowout and combustion instabilities that become more prominent when varying the hydrogen-carbon ratio significantly. Our intent is to provide a clear and concise reference to edify the reader examining attributes of fuels with different properties and how natural gas is superior to other fossil fuels with lower hydrogen carbon ratios in terms of carbon emissions, power, and efficiency.
Performance Comparison of Internal and External Reforming for Hybrid SOFC-GT Applications by Using 1D Real-Time Fuel Cell Mode
Authors: Chen Hao , Yang Chen , Zhou Nana , Harun Nor Farida , Tucker David 
Published: November 2019

Abstract
Solid oxide fuel cells integrated with gas turbine (SOFC-GT) systems are considered among the most promising power generation units, not only because of the high efficiency, low emissions and carbon capture ability, but also the flexibility to use different kinds of fuels such as natural gas, syngas and biogas directly. In the case of natural gas, Previous researches have demonstrated that solid oxide fuel cells possess the ability to utilize natural gas directly by reforming it inside the anode because of the high operating temperature. But the major problem of internal reforming is that it increases the temperature gradient at the leading edge of fuel cell which may lead to high thermal stress and damage the cells. On the other side, external reforming requires an additional reformer outside of fuel cell, which may increase the investment costs. Also, the amount of air needed to cool the fuel cell is doubled, compared with internal reforming. A full comparison between internal reforming and external reforming of the pressurized SOFC is needed for the hybrids application.
In this paper, a real time equilibrium reformer model based on minimization of Gibbs free energy was built to couple with 1D real time solid oxide fuel cell model. An internal on-anode reforming SOFC stack configuration for hybrid SOFC-GT system application was compared with external reforming configurations with 800K, 900K and 1000K reforming temperatures. The results show that internal reforming provides better performance of SOFC stack in the case of high fuel utilization. However, the external reforming showed a higher stack efficiency and smaller stack size compared with on-anode reforming when keeping a relatively lower SOFC stack fuel utilization, necessarily for high hybrid efficiency. Results indicated that external and internal reforming of fuel needs to be optimized depending on different design conditions of the entire hybrid system in terms of efficiency and investment cost. This paper shows that the hybrid system provides the opportunities for thermal integration on performance and efficiency improvement over fuel cell anode reforming.
A Bayesian Framework for Estimation of Strain Life Lower Bounds and its Application to IN617
Authors: Dourado Arinan , Irmak Firat , Viana Felipe A. C. , Gordon Ali P. 
Published: November 2019

Abstract
The practice of applying strain-life relationships to model materials subjected to low cycle fatigue conditions has been widely-accepted for the past seventy years. The Coffin-Manson rule employs a double, two-parameter power law equation to correlate cycles to failure to strain range (or vice versa). Plastic strain range dominates low life, while elastic strain dominates high life. In some settings with well-established materials, copious amounts of test data are available. The median response and the Coffin-Manson parameters are determined through regression. Scatter in both strain amplitude and fatigue life values are a consequence of material and specimen variation, test technician attributes or more. Recent initiatives have endeavored to transition deterministic approaches over to probabilistic analogies. Confidence bands, lower ones in particular, are useful for understanding reliability curves and implementing reliability-based design and optimization. In settings with accelerated product development schedules, intentionally sparse sets of test data are used to play “what if” scenarios in the context of life prediction. We propose a non-stationary variance to model deviations from the Coffin-Manson rule and use Bayesian statistical methods to estimate model parameter uncertainties. The proposed approach is applied to the calibration of strain-life parameters of the candidate material Inconel 617, a Ni-base alloy used is combustion equipment. When compared with constant variance (such as in traditional regression), the results show an improved characterization of the confidence bounds for fatigue life. This is important as it indicates that the methodology can be used to manage the number of coupon test to achieve an acceptable convergence.
Auto Ignition Study of Methane and Bio Alcohol Fuel Blends
Authors: Zheng Xuan , Jouzdani Shirin , Akih-Kumgeh Benjamin 
Published: November 2019

Abstract
Methane (CH4) and bio alcohols have different ignition properties. These have been extensively studied and the resulting experimental data have been used to validate chemical kinetic models. Methane is the main component of natural gas, which is of interest because of its relative availability and lower emissions compared to other hydrocarbon fuels. Given growing interest in fuel-flexible systems, there can be situations in which the combustion properties of natural gas need to be modified by adding biofuels, such as bio alcohols. This can occur in dual fuel internal combustion engines or gas turbines with dual fuel capabilities. The combustion behavior of such blends can be understood by studying the auto ignition properties in fundamental combustion experiments. Studies of the ignition of such blends are very limited in the literature.
In this work, the auto ignition of methane and bio alcohol fuel blends is investigated using a shock tube facility. The chosen bio alcohols are ethanol (C2H5OH) and n-propanol (NC3H7OH). Experiments are carried out at 3 atm and 10 atm for stoichiometric and lean mixtures of fuel, oxygen, and argon. The ignition delay times of the pure fuels are first established at conditions of constant oxygen concentration and comparable pressures. The ignition delay times of blends with 50% methane are then measured. The pyrolysis kinetics of the blends is further explored by measuring CO formation during pyrolysis of the alcohol and methane-alcohol blends. The resulting experimental data are compared with the predictions of selected chemical kinetic models to establish the ability of these models to predict the disproportionate enhancement of methane ignition by the added alcohol.
Governing Parameters Influencing CMAS Adhesion and Infiltration Into Environmental/Thermal Barrier Coatings in Gas Turbine Engines
Authors: Ghoshal Anindya , Walock Michael J. , Murugan Muthuvel , Mock Clara , Bravo Luis , Pepi Marc , Nieto Andy , Wright Andrew , Luo Jian , Jain Nishan , Flatau Alison , Fehrenbacher Larry 
Published: November 2019

Abstract
Sand particulate ingestion into modern gas turbine engines for fixed wing and vertical lift aircraft is a significant challenge for both military and civilian missions. ARL as part of a DoD funded Laboratory University Collaborative Initiative (LUCI) and Vannevar Bush Fellowship at UCSD are investigating the governing parameters that primarily influences the CMAS adhesion kinetics and infiltration on the standard Yttria Stabilized Zirconia (YSZ) as part of metallic single crystal Nickel superalloys TBC and SiC/SiC CMC T/EBCs. Current research shows various parameters including CMAS viscosity, porosity, adhesion strength, contact angle (wettability factor), geological factors affecting sand formation, coating and structural substrate roughness and surface temperature, internal flow Reynolds number, temperature, pressure, Mach number, boundary layer and bleed air, coating process (columnar vs splat morphology), tortuosity factor et al affects the CMAS adhesion and infiltration. This paper is a summary of our current research to identify and study the governing parameters that affects the CMAS formation, adhesion and infiltration and the underlying interfaces between CMAS and T/EBC, bond coat and the structural substrate. This work is aligned with Army Modernization Priority Future Vertical Lift and PEO Aviation Advanced Turbine Engine (ATE) Program.
Design and Numeric Simulation of a Thermoacoustic Bi-Directional Turbine Test Rig
Authors: Liu Dongdong , Chen Yanyan , Dai Wei , Luo Ercang 
Published: November 2019

Abstract
As a new type of acoustic-electric conversion method, bi-directional impulse turbine provides great potential for developing large scale and economic thermoacoustic power generators. A test rig for turbine tests in acoustic fields, which are provided through two reciprocating pistons, has been introduced. A three-dimensional numerical model has been used to simulate the whole system. The fundamental characteristics of the turbine in oscillating flow are analyzed. Impact of acoustic field features on the turbine performance has been studied. The results show that the performance is sensitive to the acoustic field. For the test rig, a typical result is that with a shaft power of 187 W, the turbine can reach an efficiency around 32%.