bluuebunny/crossref_metadata_2025_split huggingface dataset:
Forced Response Analysis of a Radial Turbine With Different Modelling Methods
Authors: Gao Yang , Gutierrez Salas Mauricio , Petrie-Repar Paul , Gezork Tobias 
Published: November 2019

Abstract
Forced response analysis is a critical part in the radial turbine design process. It estimates the vibration mode and level due to aerodynamic excitations and then enables the analysis of high-cycle fatigue (HCF) to determine the life span of the turbine stage. Two key aspects of the forced response analysis are the determination of the aerodynamic forcing and damping which can be calculated from unsteady 3D computational fluid dynamics (CFD) simulations. These simulations are problematic due to the high level of complexity in the simulations (multi-row, full annular, tip gap, etc.) and the consequent high-computational cost. The aim of this paper is to investigate and compare different CFD methods applied to the forced response analysis of a radial turbine. Full annular simulations are performed for the prediction of the excitation force. This method is taken as the baseline and is usually the most time-consuming one. One method of reducing the computational effort is to use Phase-lag periodic boundary conditions. A further reduction can be obtained by using a frequency-based method called nonlinear harmonic. For the prediction of aero-damping, the Phase -lag periodic boundary condition method is also available. Moreover, a frequency-based method called harmonic balance can further accelerate the aero-damping calculation. In this paper, these CFD methods will be applied to the simulations of an open-geometry radial turbine with a vaned volute. A comparison of unsteady results from different methods will be presented. These unsteady results will also be implemented to a tuned forced response analysis in order to directly compare the corresponding maximum blade vibration amplitudes.
Experimental and Numerical Analysis of Additively Manufactured Inconel 718 Coupons With Lattice Structure
Authors: Parbat Sarwesh , Min Zheng , Yang Li , Chyu Minking 
Published: November 2019

Abstract
In the present paper, lattice geometries have been developed and tested for application in internal cooling of gas turbine blades. These geometries are suitable for embedding within a near surface or double wall cooling configuration. Two types of unit cells with variation in number of ligaments and porosity, were used to generate two lattice configurations. The first type of unit cell consisted of six ligaments of 0.5 mm diameter joined at a common vertex situated at the middle. As such, three ligaments were located on each side of the common middle vertex. In addition, the top half of the unit cell was rotated 60 degrees compared to the bottom half of the unit cell. The second type of unit cell was derived from the first type but with four mutually perpendicular ligaments added in the middle plane. Two lattices, referred to as L1 and L2, were obtained by repeating the type 1 and type 2 unit cells, respectively, in both streamwise and spanwise directions. The test coupons consisted of these lattice structures embedded inside a channel of 2.54 mm height, 38.07 mm width and 38.1 mm in length. The coupons were fabricated using Inconel 718 powder through selective laser sintering (SLS) process. The heat transfer and pressure drop performance was evaluated using steady state tests with constant wall temperature boundary condition and for channel Reynolds number ranging from 2,800 to 15,000. In addition, steady state numerical conjugate heat transfer simulations were conducted to obtain a detailed insight into the prevalent flow field and temperature distribution. Experimental results showed a heat transfer enhancement of upto 3 times at the highest Reynolds number compared to a smooth channel. Both the heat transfer and pressure drop increased with a decrease in the porosity from L1 to L2. The numerical results revealed formation of prominent vortical structures in the inter-unit cell spaces. These vortical structures were located in the upper half of the channel causing an increased heat transfer on the top end wall. As a result, these lattice structures provided an augmented heat transfer with a potential for favorable redistribution of the coolant.
Study on the Smart Diagnosis of Gas Turbine With Distributed Computing Technique
Authors: Wu Hang , Chen Jinwei , Zhang Huisheng 
Published: November 2019

Abstract
Monitoring and diagnosis of a gas turbine is a critical issue in equipment maintenance field. Traditional diagnosis methods are established on the basis of physical models. However, the complexity and degradation of gas turbine limit both comprehensiveness and accuracy of these physical models, making the diagnosis less effective. Therefore, data-driven models are introduced to supplement and revise previous models.
Benefitting from the prosperous development of machine learning, neural network has been greatly improved and widely used in various fields of data mining. Three neural networks, Multilayer Perceptron, Convolutional Neural Network and Long Short-term Memory Network are applied in data-driven model establishment. Their training time and prediction accuracy are the two most important factors in judging the effectiveness.
An active real time training which means training and predicting simultaneously is applied as the main modelling method for an on-line diagnosis system. Three periods are defined according to the time line: data preparation period, model establishing period and stable prediction period. From the three above neural networks, the most effective data-driven models that corresponding to the last two periods are tested and selected, the purpose is to ensure the high level of accuracy.
When high level of accuracy is demanded, neural network always need large computing time and memory space in data learning process. To avoid prediction delay and keep rapid response for the coming fault, distributed training on a 1-master 2-workers computer cluster is designed and applied in this system. Two types of data parallelism are realized on the cluster through Apache Spark and Shell Script for Linux. Comparing with each other and the local training mode, the results shows that dispensing data at first and averaging parameters at last reaches a better outcome both in high accuracy and low training time.
Accurate Field Compressor Inlet Flow Measurement System
Authors: McConkey Joshua , Bunce Richard H. , Claussen Heiko 
Published: November 2019

Abstract
Understanding the amount of air that enters a gas turbine is important for calculating their performance and efficiency. Flow meters are almost never used to measure that flow in production engines. Typical flow meters are impractical because the air flow into the compressor is very large, up to 1400 lbs/s (635 kg/s) or 1,000,000 ft3/min (28,300 m3/min), and typically an intentional pressure drop is involved in the measurement. This pressure drop negatively impacts the performance of the engine. If inlet air mass flow were known accurately without negatively impacting the engine performance, then engines could be run more efficiently. Currently, inlet mass flow is typically inferred, rather than measured. This leads to increased safety margins which require engines to be run more conservatively, i.e., at lower power. This paper describes a novel, inexpensive, and accurate air mass flow measurement system with negligible impact on engine performance.
AeroEngineS: Multi-Platform Application for Aero Engine Simulation and Compressor Map Operating Point Prediction
Authors: Pontika Evangelia C. , Kalfas Anestis I. , Aslanidou Ioanna 
Published: November 2019

Abstract
This paper presents the development of AeroEngineS (Aircraft Engine Simulation), a multi-platform app with graphical user interface for aero engine simulation and compressor map operating point prediction.
Gas turbine performance simulation is a crucial part of the design process. It provides information about the required operating conditions of all the components and the overall performance of the engine so that engineers can determine whether the current engine configuration meets the performance requirements. Some gas turbine simulation programs have been developed in the last decades, however, there was a lack of an open-source, lightweight, user-friendly, but still very accurate, application which would be easily accessible from all platforms.
AeroEngineS can be used as a user-friendly preliminary design tool, since, during this design phase, details about the geometry are not known yet. The main aim is to calculate simply and quickly the basic parameters of the thermodynamic cycle and the performance, in order to determine which design is able to meet the required specifications. AeroEngineS constitutes a free and simple app which can primarily serve educational purposes as it is easily accessible by students from any platform to assist them in aero engine technology courses. Secondarily, it has the potential to be used even by engineers as a quick tool accessible from all devices.
The app consists of two basic stand-alone functions. The first function is aero engine simulation at Design Point which solves thermodynamic calculations. The second function is compressor map operating point prediction using a novel method of combining scaling techniques and Artificial Neural Networks.
High Pressure Novel Single Hub Multi-Rotor Centrifugal Compressor: Performance Prediction and Loss Analysis
Authors: Muppana Sai , Siddappaji Kiran , Abdallah Shaaban 
Published: November 2019

Abstract
Blade loading on a single stage high pressure centrifugal compressor is limited due to separation that might occur on the suction side of the airfoil at mass flow rates lower than design point. A novel configuration of centrifugal compressor is designed and analyzed to overcome this issue by placing multiple rotors on the same hub with a stator vane in between similar to a multi-stage axial compressor blade arrangement. By having independent rotors, blade loading can be distributed more efficiently and higher pressure rise can be achieved through this design. As the blade chord length is reduced due to splitting of single impeller blade, the effective turning angle is divided through several stages thereby lowering the adverse pressure gradient reducing the chance of separation. Stator vanes are placed in between the rotors so that the successive rotor receives the flow at desired incidence angle. The attempt here is to apply the same principle of axial compressor multi-staging on a centrifugal compressor and compare the performance with single stage using low to high fidelity analysis framework developed in-house. A low fidelity 1D analysis tool CIMdes is used for evaluating blade angles and stage degree of reaction which are exported to T-blade3, in-house parametric geometry tool, for 3D blade generation. These blades are further analyzed using 3D CFD analysis using an in-house automated multifidelity framework. Loss quantification revealed that diffuser losses are higher in singlestage and the novel design increased the backsweep angle resulting in lower diffuser losses. Splitting the single rotor facilitated the increase in backsweep angle to a larger range as compared to single rotor impeller configurations. Two configurations with different shroud height for the single stage compressors are investigated and compared with the novel compressor with respective flowpaths at 100% speedline using a multi-fidelity design analysis suite. The flow capacity is extended near the stall with a penalty in efficiency for configuration-1. Configuration-2 showed an improvement in efficiency at design mass flow rate. The preliminary analysis demonstrates the advantages of the multi-staging on the same hub and extends the design space for performance range improvement with some trade-offs.
Combustion Characterization of a Fuel-Flexible Piloted Liquid-Spray Flame Apparatus Using Advanced Laser Diagnostics
Authors: Wang Yejun , Paschal Tyler , Kulatilaka Waruna D. 
Published: November 2019

Abstract
Primary energy sources for aviation gas turbines as well as direct-injection gasoline and diesel engines come in the form of liquid hydrocarbon fuels. These liquid fuels are atomized and mixed with air, prior to highly turbulent combustion and heat release processes inside engine hardware. Designing more efficient and cleaner gas turbine engines is hence dependent on the in-depth understanding of spray formation, mixing, heat release, combustion dynamics, and pollutant formation pathways in liquid-fuel spray flames. As compared to gaseous fuels, the additional steps of atomization, dispersion, and evaporation prior to turbulent mixing need to be considered for a variety of liquid fuels to enable fuel-flexible operation of these combustion hardware. Such studies can be largely facilitated by advanced laser diagnostics applied to simplified piloted liquid-spray flame configurations that can also be numerically modeled using well-defined boundary conditions. In this work, a modified configuration of a fuel-flexible piloted liquid-spray flame apparatus is used for detailed laser diagnostics studies using hydroxyl (OH) planar imaging. The configuration consists of a modified McKenna flat-flame burner fitted with a direct-injection high-efficiency nebulizer. OH radical is a primary marker of the reaction zone and a key indicator of the heat release process in flames. OH is abundant in the high-temperature combustion regions providing high signal-to-noise ratio single-laser-shot images revealing flame dynamics and instabilities. Therefore, OH planar laser-induced fluorescence (PLIF) is employed to characterize the dynamic structures of a range of piloted liquid-spray flames operated with methanol (CH3OH), n-Heptane (C7H16), iso-Octane (C8H18), dodecane (C12H26), gasoline (C4–C12), diesel (C12–C20), and kerosene (C6–C16). Single-shot and averaged OH-PLIF images show the presence of strong turbulence in the core region above the surface of the McKenna burner. The reaction zone mainly occurs around the periphery of this region, then it spreads more uniformly due to evaporation of liquid droplets downstream of the spray flame. Two-color OH PLIF thermometry in liquid spray flames operated with gasoline, diesel and kerosene, has been shown that the combustion temperature is in the range of 1200–2000 K. Overall, OH PLIF has been demonstrated to be an efficient approach for dynamic structures and temperature measurements in piloted liquid-spray flames operated with realistic fuels.
Response Surface Mapping and Multi-Objective Optimization of Crowning and Tapers in Water-Lubricated Thrust Bearings
Authors: Deng Xin , Watson Cori , He Minhui , Fittro Roger , Wood Houston 
Published: November 2019

Abstract
Fluid film bearings for turbomachinery are designed to support the loads applied by the rotor system. Oil-lubricated bearings are widely used in high speed rotating machines. However, environmental issues and risk-averse operations have made water lubricated bearings increasingly popular. Due to different viscosity properties between oil and water, the low viscosity of water decreases film thickness significantly. Crowning and tapers are two main ways to maintain the film thickness requirements in water lubrication, but no studies about the influence of these parameters on the film thickness in water-lubricated bearings have been reported. Therefore, further understanding of the performance associated with optimizing the bearing design with different weighted performance and their relationships to bearing design variables could be invaluable to bearing design engineers.
This study explores the impact of three crowning and taper design variables on the performance of one tilting pad thrust bearing using the design of experiments techniques applied to a thermoelastohydrodynamic (TEHD) bearing model. The bearing design variables analyzed in this study include the radius of the ground-in crown, taper circumferential angle offset, and the vertical taper distance at the inner and outer radii. Each of the design variables is first varied over five levels, each in central composite design. The outputs from the TEHD numerical simulations used as performance measures for each bearing design point were the minimum film thickness, the film thickness at the pivot location, maximum film pressure and power loss.
Multi-objective optimization was performed. A range of weighting parameters was selected for the optimization function to find a bearing design that maintains the minimum film thickness criterion while minimizing power loss. The resulting optimum design points allowed for a comparison between the design optimization at different weightings. This study demonstrates how designers can use these approaches to view the relationships between design variables and important performance metrics to design better bearing for a wide range of applications.
Numerical Investigation of Pin-Fin Influences on Cooling Air Flow Characteristics in Blade Trailing Edge Region
Authors: Wu Weilong , Xu Huazhao , Wang Jianhua , Wu Xiangyu , Wang Lei 
Published: November 2019

Abstract
This paper numerically investigated the influences of pin-fin size and layout on the flow characteristics of cooling air in the trailing edge of a real low pressure turbine blade. The discussion was given first for the baseline model without pin fins (denoted as M0) under a turbine design condition and two off design conditions. Then a comparison of the flow fields in the turbine blade especially in the trailing edge region was performed with three more trailing edge models, with the purpose of discovering the benefits of using pin fin configurations in a real low pressure turbine blade. The other three models (denoted as M1, M2, M3) have pin fins in different diameters and arrangements. The M1 model has a row of 13 pin fins with a diameter of 2mm, and the M2 and M3 models have two rows of pin fins arranged in a staggered pattern with a diameter of 1.2mm. Compared to the baseline model M0, it is shown that an addition of pin fin configurations helps greatly to improve cooling flow distributions and to mitigate the blockage of coolant in trailing slots. Meanwhile, the adoption of pin fins has not only affected significantly the flow field in the trailing passage but also has moderately affected flow fields in the middle and forward cooling passages. Increasing pressure ratio can increase total mass flow rate with no significant change in flow patterns. The baseline blade Model M0 shows a high value of 6 for a friction loss related performance function at the turbine design condition. However, only a moderate increase in the value of the performance function is discovered for all the three blades with pin fins.
Design and Maintenance Issues of Being Able to Repair Marine Gas Turbines Without Removal From the Ship
Authors: Thompson Bruce D. , Hartranft John J. , Groghan Dan 
Published: November 2019

Abstract
When the concept of aircraft derivative marine gas turbines were originally proposed, one of the selling points was the engine was going to be easy to remove and replace thereby minimizing the operational impact on the ship. Anticipated Mean Time Between Removal (MTBR) of these engines was expected to be approximately 3000 hours, due mostly to turbine corrosion damage. This drove the design and construction of elaborate removal routes into the engine intakes; the expected time to remove and replace the engine was expected to be less than five days. However, when the first USN gas turbine destroyers started operating, it was discovered that turbine corrosion damage was not the problem that drove engine maintenance. The issues that drove engine maintenance were the accessories, the compressor, combustors and engine vibration. Turbine corrosion was discovered to be a longer term affect. This was primarily due to the turbine blade and vane coatings used and intake air filtration. This paper discusses how engine design, tooling development, maintenance procedure development and engine design improvements all contributed to extending the MTBR of USN propulsion and electrical power generation gas turbines on the DD 963, CG 47, DDG 51 and FFG 7 classes to greater than 20,000 hours. The ability to remove the gas turbine rapidly or in most cases repair the engine in-place has given the USN great maintenance flexibility, been very cost effective and not impacted operational readiness.
Structural Optimization of Fir-Tree Root and Groove for Turbine Blade With Superellipse and P-Norm Aggregation Function
Authors: Yu Deqi , Zhang Xiaojuan , Yang Jiandao , Cheng Kai , Li Ming 
Published: November 2019

Abstract
Due to its finite size and the large centrifugal load, the fir-tree root is highly stressed, which leads to the possible early failure of the gas turbine and steam turbine. To find an optimized fir-tree root is an important issue for the design of the turbine structures. In this paper, a superellipse-based design optimization approach is proposed for the fir-tree root. Rather than the straight line and arc used in literature, the combination of the superellipse curve and line are employed to characterize the fir-tree root since the superellipse curve represents a large family of curves with limited parameters, which makes the design optimization easy and economic. For the design optimization, the objective function is to minimize the peak stress, which is a typical min-max problem with possible severe iterative oscillation and subsequent convergence difficulty. To avoid this problem, a P-norm aggregation function is proposed. The superellipse parameters are defined as design variables, while the stress concentration factor and the stress at root neck are specified as optimization constraints. With the P-series fir-tree root design as example, it is proved that our approach is effective to find the optimized configuration with better stress distribution and lower stress concentration.
The Influence of Geometric and Aerodynamic Boundary Conditions on Fuel Injector Feed and External Aerodynamics for Lean Burn Combustors
Authors: Li Y. , Denman P. A. , Walker A. D. 
Published: November 2019

Abstract
Lean burn combustion is currently a preferred technology to meet the future low emission requirements faced by aero gas turbines. Previous work has shown that the increased air mass flow and size of lean burn fuel injector alters the necessary redistribution of the airflow leaving the high-pressure compressor. This can lead to flow field non-uniformities in the feed to combustor annuli and the fuel injectors which have the potential to impact the overall performance of the combustion system. This paper presents a systematic assessment of the effect of several aerodynamic parameters on the air flow feed to the fuel injectors and the external combustion system aerodynamics for a generic lean burn system. This includes the effect of changes to the flow splits between various combustor cooling features and annulus flows and the effect of a biased compressor exit profile. Flow field data are generated using an isothermal RANS CFD model which is validated against test rig data. The data show that changes in the flow split between the annuli modified the flow uniformity and loss to both the combustor annuli and the fuel injector feed. Changes in the compressor exit profile have a larger effect introducing more notable variations in both flow uniformity and loss. Changes to the angle of the flame tube did not greatly affect the pre-diffuser but did modify annulus loss. Further analysis showed that changes to the combustor annulus flow split, compressor exit profile and flame tube angle modified the location, at compressor exit, of the flow captured by the annuli or each fuel injector passage. The loss to each of these depends on the flow quality (total pressure and uniformity) and from the source more than the flow uniformity delivered.