bluuebunny/crossref_metadata_2025_split huggingface dataset:
Measurement and Abatement of PM Emitted by Stationary Gas Turbines: Experience Gained With Different Fuels and Combustor Types
Authors: Komodromos Aristotelis , Moniatis George , Kontopoulos Frixos , Zaimis George , Vierling Matthieu , Aboujaib Maher , Sokolov Dmitry , Montagne Pierre , Catrin Sven , Karpouzas Dimitris , Vamvarapis Panagiotis , Molière Michel 
Published: August 2018

Whichever the type of combustion installation, liquid fuels burned in gas turbines tend to generate particulate matter (PM) emissions, which consist in soot only or in ash plus soot, according to their ash-free or ash-forming character.
Standard diffusion flame combustion systems are known as “universal” combustors, capable to burn both ash-free (naphtha, light and heavy distillates) and ash-forming (crude and heavy) fuels. In contrast, DLN systems are designed to burn gaseous fuels and light distillates.
PMs in the range of a few parts per million represent a solid micropollutant, the measurement and abatement of which creates specific technical challenges.
In order to fully characterize soot emission and investigate their reduction, GE has undertaken a multi-year investigation program covering (i) an exploratory engineering study starting from the EN13284-1 standard and (ii) the testing of a number of inorganic oxidation catalysts used in the form of fuel additives (“soot inhibitors”).
In this framework, a joint work involving GE and Electricity Authority of Cyprus has been conducted in the first half of 2017 and a full-scale test plan has been performed at the Vasilikos power plant in Cyprus, involving a Frame 6F.03 DLN2.6 that burns light distillate oil and is equipped with a DeNOx water injection system. Four types of soot inhibitor additives: cerium (IV) and (III), iron (III) and (II) were tested. This paper reviews the results of this field test and compares them with data previously acquired at other power plants featuring different liquid fuels and combustion systems.
Its goal is to provide the gas turbine community with a better understanding of PM emissions and their abatement using various soot inhibitor candidates, in function of liquid fuel type and combustion system.
Optimization of Fuel Two-Stage Screw Centrifugal Pump of Rocket Powerful Turbopump Unit
Authors: Zubanov Vasilii , Volkov Andrei , Matveev Valeriy , Popov Grigorii , Baturin Oleg 
Published: August 2018

The article describes a refining method for a fuel pump of rocket powerful turbo-pump unit by the joint usage of mathematical optimization software IOSO, meshing complex NUMECA and CFD complex ANSYS CFX. The optimization software was used for automatic change of the geometry of low-pressure impeller, transition duct and high-pressure impeller to find the optimal design. It was mandatory to keep the original variant of the remaining parts of the pump. For this reason, only geometrical parameters of the blades were varied without changing the contours of the pump meridional flow part.
The investigated pump consists of five parts: inlet duct, low-pressure screw centrifugal stage, transition duct, high-pressure screw centrifugal stage and volute outlet duct. The pump main parameters with water as the working fluid (based on experiment data) were the following: high-pressure stage rotor speed was 13300 rpm; low-pressure rotor speed was 3617 rpm by gearbox; inlet total pressure was 0.4 MPa; outlet mass flow was 132.6 kg/s at the nominal mode.
Creation of vane unit mesh (rotors and stator transition duct) was performed using NUMECA AutoGrid5. Sector models were used for the calculation simplification. The flow around only one blade or screw was considered. Setting up and solution of the task were carried out in the ANSYS CFX solver. Comparison of calculated characteristics of the basic pump with the experimental data was performed before the optimization.
The analysis of characteristics for the obtained optimized pump geometry was carried out. It was found that pump with optimized geometry has greater efficiency in comparison with the original pump variant. The obtained reserve can be used to boost the rocket engine, and/or to reduce the loading of the main turbine, which operates in aggressive oxidizing environment.
Unsteady Flow Effects on Steam Turbine Last Stage Blades at Very Low Load Operating Condition
Authors: Tanuma Tadashi , Ogawa Michio , Okuda Hiroshi , Hashimoto Gaku , Shibukawa Naoki , Okuno Kenichi , Tsukuda Tomohiko 
Published: August 2018

Unsteady aerodynamic and structural interactive analysis method for design and development of highly efficient low pressure last stage blades and results of its main application on very low load conditions are reported in this paper.
Main features of this method are the enhanced analysis scope including very low load conditions and validations using measured data of real steam turbines including very low load conditions as well. Our schemes for this project were introducing boundary conditions from measured data in real steam turbines, full annulus all blade unsteady aerodynamic analysis and large scale parallel computing for unsteady structural analysis.
The aerodynamic analysis results indicate that one root cause of the relatively large blade vibration at low load conditions seems to be a tip vortex induced by the blade windage.
A modified method that introduced accurate structural analysis boundary condition data from aerodynamic analysis results is demonstrated. The structural analysis of a six-blade group with lacing wire dumping structure was performed.
Compressor Instability Analysis Within an Hybrid System Subject to Cycle Uncertainties
Authors: Cuneo Alessandra , Traverso Alberto , Massardo Aristide F. 
Published: August 2018

The transient/dynamic modeling of energy systems can be used for different purposes. Important information can be obtained and used for the design phase. The control system and strategies can be safely tested on transient/dynamic models in simulation, increasing the confidence during experimental phase. Furthermore, these models can be used to acquire useful information for safety case. The analysis of energy systems in dynamic conditions is generally performed considering fixed values for both geometrical and operational parameters such as volumes, orifices, but also initial temperatures, pressure, etc. However, such characteristics are often subject to uncertainty, either because they are not known accurately or because they may depend on the operating conditions at the beginning of the relevant transient. With focus on a micro-gas turbine fuel cell hybrid system, compressor surge may or may not occur during transients, depending on the aforementioned cycle characteristics; hence compressor surge events are affected by uncertainty.
In this paper, a stochastic analysis was performed taking into account an emergency shut-down in a fuel cell gas turbine hybrid system, modelled with TRANSEO, a deterministic tool for the transient and dynamic simulations of energy systems. The aim of the paper is to identify the main parameters that impact on compressor surge margin. The stochastic analysis was performed through the RSA (Response Sensitivity Analysis) method, a sensitivity-based approximation approach that overcomes the computational burden of sampling methods such as MCS (Monte-Carlo Simulation). The results show that the minimum surge margin occurs in two different ranges of rotational speed: a high-speed range and a low-speed range, the latter being more sensitive for surge occurrence. The temperature and geometrical characteristic of the outer pressure vessel, where the fuel cell is installed, are the two main parameters that affect the surge margin during an emergency shut down.
Development of a Robust LP Blade Family for Variable Speed Applications
Authors: Schubert Martin , Tusche Johannes 
Published: August 2018

Industrial steam turbine applications require a high flexibility in terms of aerodynamically as well as mechanically operating conditions. Mechanical drives run at variable rotor speeds and often face high backpressure levels, which is a particularly challenging aspect for the last-stage moving blade (LSMB) row of a low-pressure (LP) steam turbine. As speed synchronous blade resonances cannot be excluded over the entire operating speed range, the LSMB needs to be designed resonance proof from viewpoint of dynamics and mechanical strength.
The subsequent paper describes a new developed LP stage group for variable speed applications, which is available as fully scaled blade family with distinct exhaust area and rotational speed limit reaching from conventional 3000rpm up to high speed utilities for special purposes. It consists of two standard stages, which can be operated at off resonance as well as resonance conditions. For that reason frictional elements were implemented in both moving blade rows. They are loosely assembled into pockets, which are placed on the pressure as well as suction side of each airfoil. Basically, this feature was already introduced for certain Siemens LP blades, see [1], [2], [3] and [4]. However, the recent development on this field utilizes several design changes for the benefit of robustness and reliability. The present paper focuses on the non-linear dynamic behavior of the friction damped, coupled blade rows and outlines the underlying design method as well as calculation process.
Incremental Modeling of Rotor Lifetime Consumption During Gas Turbine Operation
Authors: Sistaninia M. , Winge T. , Ugel D. 
Published: August 2018

In order to enable customers to operate gas turbines (GT) closer to the life limits, a life monitoring tool has been developed which computes rotor life consumption based on operation history of the GT. The tool can account for both creep and fatigue life consumption. The creep module can be applied to extend GTs creep life at high operational gas temperatures, whereas the fatigue module enables more flexible operations meaning more frequent operation at varying load conditions.
For creep monitoring a new incremental modeling approach has been developed to calculate rotor radial elongation based on the actual operation history of GTs. In this method the rate of elongation during GT operation is calculated based on a correlation with the total radial elongation and gas temperature. The results of this modeling approach have been validated against the field data of several GTs. A good agreement has been obtained between the simulation and measurement results for different rotor axial positions.
For fatigue life monitoring, the temperature based monitoring approach developed in a former publication [1] by the authors has been further adapted to rotating components in particular the rotor for which metal temperature measurement is very challenging. In this method life consumption is calculated based on the gas temperature history and GT power instead of metal temperature.
By considering the real-time data, the rotor life consumption can be more precisely calculated and as a result the GT can be operated closer to its life limits. Hence, this method can be used to increase the intervals between inspections and therefore to extend the service life of the GTs.
Digital Compressor Analytics
Authors: Bakken Martin , Lunde Erling , Bakken Lars E. 
Published: August 2018

Norwegian gas export is a high value business, where small and transient disturbances may cause substantial production losses. Process experience has shown that the compressor system may suffer considerably owing to surge and rotating stall in situations where the compressor is forced to trip. One of the main challenges concerns analysis of the actual trip trajectory to validate whether the compressor has entered the unstable area of the performance characteristics. This type of analysis is paramount with regard to compressor operation and tuning of the compressor safety system. Recent advances in data analytics and digitalization capabilities give promise of new ways to handle and analyse such challenges.
The current work presents data from a real compressor trip. The investigation reveals that plant data alone may not be sufficient for analysis of the trip trajectory. Hence, the trip scenario was analysed in light of experimental data, fan law principles and utilization of a detailed dynamic model. The results reveal that utilization of a dynamic model gives fruitful insight into the compressor system dynamics during a trip. These findings form a basis for future digitalization of the plant.
This idea will be developed into the specification of a concept called a Digital Compressor. The digital compressor may run in off-line or on-line mode with the aim of providing: high resolution estimates (soft sensors) for non-measured or inaccurate process variables; or identification of process parameters and characteristics, such as gas density. Use cases include: off-line “what happened” analysis; identifying the minimal viable instrumentation; on-line advanced condition and performance monitoring.
A digital compressor laboratory setup will be introduced, containing both a dynamic simulation system as well as a complete gas compressor rig — with all necessary computational and communication infrastructure.
A Parametric Study of the Effects of Inlet Distortion on Fan Aerodynamic Stability
Authors: Zhang Wenqiang , Vahdati Mehdi 
Published: August 2018

The performance and aerodynamic stability of fan blades operating in a circumferentially non-uniform inlet flow is a key concern in the design of turbofan engines. With the recent trends in the design of civil engines with shorter inlet ducts (such as low-speed fans), or boundary layer ingesting engines, quick and reliable modelling of rotor/distortion interactions is becoming very important. The aim of this paper is to study the effects of inlet distortions on the aerodynamic stability of a fan blade and to identify the parameters that have a major impact on the stability of the blade. NASA rotor 67, for which a significant amount of measured data is available, was used for this study.
In the first part of this study, the behavior of the fan with inlet distortion at near stall condition is analyzed, and it is shown how rotating stall is triggered. In the second part of this study, unsteady simulations with inlet distortion were performed to study how parameters, such as exit duct length and distortion strength, influence the stall margin of the blade.
A Novel Experimental Technique for Investigating Natural Convective Heat Transfer in a Gas Turbine Annulus
Authors: Fahy Daniel D. , Ireland Peter T. , Lewis Leo V. , Raya Emile 
Published: August 2018

When a gas turbine is shut down it cools asymmetrically due to natural convection. After some time, a thermal gradient develops across the rotor drum as the top section cools slower than the bottom. This induces a thermal stress that causes the shaft to deflect — a phenomenon known as rotor or thermal bow. In some cases, this can lead to compressor tip rubs. All engines are affected by rotor bow to some degree. However, the mechanisms of natural convective heat transfer and impact of design features on rotor bow is not well understood; thus, the issue is not identified until late in the design stage, hampering an engines development.
A novel experimental technique and facility has been developed that allows for accurate, detailed measurements of natural convective heat transfer in a gas turbine annulus to be made. The apparatus has the capacity to test circumferential and axial variations in temperature distribution, in addition to an isothermal wall boundary. An IR camera looking directly at the rotor surface is used to provide high-resolution heat transfer measurements. The test piece for this study consisted of a cylinder section and a conical section.
Results from the isothermal cylinder test cases agreed quite well with previously published data, which gives confidence to the method that has been employed. The addition of a conical section had a profound effect on the results; however, more work is required before a method can be developed which will accurately predict the heat transfer coefficients based on initial temperature distribution. A 2D concentric cylinder methodology has also been developed that gives results in strong agreement with previously published data. Going forward, this new facility and the CFD method will be further developed to help quantify the effect of various design features on the natural convective heat transfer performance of a large civil gas turbine.
Forced Response Sensitivity Analysis Using an Adjoint Harmonic Balance Solver
Authors: Engels-Putzka Anna , Backhaus Jan , Frey Christian 
Published: August 2018

This paper describes the development and initial application of an adjoint harmonic balance solver. The harmonic balance method is a numerical method formulated in the frequency domain which is particularly suitable for the simulation of periodic unsteady flow phenomena in turbomachinery. Successful applications of this method include unsteady aerodynamics as well as aeroacoustics and aeroelasticity. Here we focus on forced response due to the interaction of neighboring blade rows.
In the CFD-based design and optimization of turbomachinery components it is often helpful to be able to compute not only the objective values — e.g. performance data of a component — themselves, but also their sensitivities with respect to variations of the geometry. An efficient way to compute such sensitivities for a large number of geometric changes is the application of the adjoint method. While this is frequently used in the context of steady CFD, it becomes prohibitively expensive for unsteady simulations in the time domain. For unsteady methods in the frequency domain, the use of adjoint solvers is feasible, but still challenging. The present approach employs the reverse mode of algorithmic differentiation (AD) to construct a discrete adjoint of an existing harmonic balance solver in the framework of an industrially applied CFD code. The paper discusses implemen-tational issues as well as the performance of the adjoint solver, in particular regarding memory requirements. The presented method is applied to compute the sensitivities of aeroelastic objectives with respect to geometric changes in a turbine stage.
Experimental Study on Acoustic Performances of Notched Nozzle Using a Subscale Turbofan Engine
Authors: Ishii Tatsuya , Nagai Kenichiro , Oinuma Hideshi , Kagaya Ryo , Oishi Tsutomu 
Published: August 2018

This paper describes an experimental study on the acoustic performance when mixer nozzles were applied to the core of a subscale turbofan engine. The primary concern of the mixer nozzle is how to satisfy both less jet mixing noise emission and minimum impact on engine performance parameters such as thrust and fuel consumption. A notched nozzle, a nozzle with tiny dents on the trailing edge, initiates small disturbances in the shear layer, weakens the shear stress, and suppresses jet noise. The Japan Aerospace Exploration Agency (JAXA) and IHI Corporation have studied notched nozzles and found that finer and more notches are preferable for both acoustic and aerodynamic performance.
As a next step, it is necessary to maintain the tradeoff between noise suppression and impact on engine performance. To evaluate both the acoustic and aerodynamic performance with the notched nozzle, a subscale turbofan engine, DGEN380, was adopted as a demonstration engine. Experiments with this engine were conducted both in a test cell and in an open test site. The notched nozzle, together with a baseline conical nozzle and a referential serrated nozzle, i.e., a chevron nozzle, was applied to the core exhaust of the engine.
The experiment in the test cell clarified that the notched nozzle possibly provides better thrust specific fuel consumption than the referential chevron nozzle. The acoustic measurement in the open environment confirmed that the notched nozzle has the noise suppression characteristics expected from previous test results. The perceived noise levels are attenuated by 1.5 dB, which is the same as or better than the referential mixer nozzle.
Numerical Simulation of the Blade Aging Process in an Induced Draft Fan due to Long Time Exposition to Fly Ash Particles
Authors: Castorrini Alessio , Corsini Alessandro , Rispoli Franco , Venturini Paolo 
Published: August 2018

Erosion issues usually affect fans used for the extraction of exhaust gas in fluid power plants. Because of the presence of fly ash within the exhaust flow, fan blades are subjected to material wear at the leading edge, trailing edge and blade surface, and this may cause a modification of the blade aerodynamic profile, a reduction of blade chord and effective camber. All these effects results in a deterioration of the aerodynamic performance of the blade.
Prediction of erosion process in industrial applications helps to better schedule the maintenance and predict the blade life. To this aim, we report a numerical simulation of the blade aging process due to particle erosion in an induced draft fan. This is done using in-house numerical tools able to iteratively simulate the flow field, compute the particle tracking/dispersion/erosion, and modify the geometry (and mesh) according to the predicted erosion rate. A scale factor is introduced to align the simulation time and particle concentrations to a real application, and compare the results with the on-field observation.
Robust Multiphysics Optimization for Fan Blade Aerodynamic Efficiency, Structural Properties and Flutter Sensitivity
Authors: Vinogradov Kirill A. , Kretinin Gennady V. , Leshenko Igor A. , Otriakhina Kseniia V. , Fedechkin Konstantin S. , Vinogradova Olga V. , Bushmanov Vyacheslav V. , Khramin Roman V. 
Published: August 2018

A fan blade is a complicated object and obviously it is subjected to geometrical uncertainties from manufacture tolerances and other production deviations. In spite of all uncertainties a fan blade should provide stable aerodynamic efficiency and strength properties. That is why it is considered to solve a multidimensional and multidisciplinary optimization task (aerodynamics, strength and flutter sensitivity) in robust statement under geometrical uncertainties. In the proposed test case geometrical uncertainties from the fan blade manufacture tolerances and deviations are considered. The probability density function (pdf) was obtained as a result of statistical operation upon the results of blade coordinate measurements. Approximately 2500 fan blades were measured by means of CMM process to reconstruct the pdf for more than 40 geometrical uncertainties (there are blade thicknesses for different airfoil locations in several cross-sections). CFD and FEM calculations were carried out in NUMECA FINE/Turbo and ANSYS software, correspondingly.
The surrogate model technique (the response surface and the Monte-Carlo method implemented to RSM results) was applied for the uncertainty quantification and the robust optimization process for the task under consideration. APPROX software was used for surrogate model construction. The IOSO technology was employed as one of the robust optimization tools. This technology is also based on a widespread application of the response surface technique.
As a result, robust optimal solutions (the Pareto set) for all 4 considered criteria (aerodynamic efficiency, structural properties, stall margin and flutter sensitivity) were obtained. The probabilistic criteria were assessed based on the results obtained. The robust optimization results were compared with the deterministic optimization results.