bluuebunny/crossref_metadata_2025 huggingface dataset:
Analytical Expression for Concentration Overpotential of Anode-Supported Solid Oxide Fuel Cell Based on the Dusty Gas Model
Authors: Das Sandipan Kumar
Published: January 2020

The Dusty Gas model (DGM), despite being arguably the most accurate representation of gas diffusion in electrodes, is not readily adopted in the literature as it entails relatively expensive numerical integration of differential equations for concentration polarization calculations. To address this issue, this article demonstrates an analytical procedure to solve the DGM equations in a fuel cell electrode setting. In the process, it highlights the differences with previous attempts in the literature and improves upon the shortcomings. This paper specifically provides explicit expressions of concentration overpotentials of anode-supported solid oxide fuel cells (SOFCs) for binary and ternary gas systems via the analytical solution of DGM equations in one dimension without considering the viscous effects. The model predictions match very well with the experimental data available in the open literature. This paper also provides a semi-analytical framework for higher-order multicomponent systems. Finally, the effect of the pore-size distribution in the porous electrode on the concentration polarization is thoroughly explored.
Retracted: “Application of Proper Orthogonal Composition Method in Unsteady Flow Field Analysis of Axial High Bypass Fan” [ASME 2019 Gas Turbine India Conference, Volume 1: Compressors, Fans, and Pumps; Turbines; Heat Transfer; Structures and Dynamics, Chennai, India, December 5–6, 2019, Conference Sponsors: International Gas Turbine Institute, ISBN: 978-0-7918-8352-5, Copyright © 2019 by ASME. Paper No: GTINDIA2019-2305, pp. V001T01A001; 6 pages; doi: 10.1115/GTINDIA2019-2305]
Authors: ASME
Published: January 2020

The above referenced paper has been removed from publication. (April 21, 2020)

Copyright © 2020 by ASME
CFD Based Taguchi Optimization of the Performance of a Gas Turbine Combustor
Authors: Pandey Mukund Kumar , Sivaramakrishna G. , Navindgi R. D. , Muthuveerappan N.
Published: January 2020

Achieving minimum pressure loss and exit temperature pattern factors are the two important, but conflicting performance goals of a gas turbine combustor. In this study, Taguchi method was used to design CFD (Computational Fluid Dynamics) analysis based experiments in order to arrive at optimized liner hole sizes (primary and dilution) of an annular gas turbine combustor. The CFD experiments were steady & three-dimensional Reynolds Averaged Navier-Stokes (RANS) based analyses performed on a 20-degree sector combustor model. Nine CFD analyses were performed as per the Taguchi L-9 orthogonal array, based on which, an optimal hole configuration was arrived. An additional CFD run was carried out to verify the predicted result. The optimized hole size combination reduces the Circumferential Pattern Factor (CPF) by 28% and pressure loss by 0.06% (difference between absolute values of percentage pressure losses) in comparison to the baseline configuration.
Parametric Analysis and Performance Evaluation of 2D Scramjet Inlet
Authors: Kane Aniruddha Ajay , Peetala Ravi K.
Published: January 2020

The air breathing propulsion system used for hypersonic vehicle cruising is a scramjet. Inlet design is one of the important step in overall design of scramjet. The initial steps in the inlet design process consist of identification of shock angles, shock hitting points and there after evaluation of performance parameters using inviscid flow consideration at a given Mach number called design Mach number. During the flight, the vehicle operates on the off-design conditions. The current study focusses on the effect of these off-design conditions such as variation of freestream Mach number, angle of attack, total temperature on the flow field and performance parameters using inviscid flow assumption. The performance parameters considered in the present study are total pressure recovery, static pressure ratio, static temperature ratio, kinetic energy efficiency, adiabatic compression efficiency, non-dimensional entropy increase.
Case Study of a Gas Turbine Chronic Failure at Saudi Arabia
Authors: AlKhudhayr Abdullah N. , AlAdel Abdulrahman M.
Published: January 2020

A gas turbine is a reliable type of rotating equipment, utilized in various applications. It is well known in power generation and aviation. In the oil and gas industry, gas turbines are utilized in locations with limited electrical power or a high power driven load requirement, such as offshore or a high-rated power 20MW compressor.

Five gas turbines are used as mechanical drive equipment. After a few years of operation, the gas turbines were experiencing high operating temperatures in bearings, turbine compartments, high spread temperature, and the presence of smoke in the exhaust. During a major overhaul of the turbines, oil was found to have accumulated internally in the wrapper casing, along with damage to several internal combustion components. In one case, the exhaust casing experienced severe damage with deformation. This paper presents a case study of a gas turbine failure and its contributors. The paper explains the mitigated solution to overcome the challenges related to the gas turbine operation, maintenance, and machine design.
Sealing in Fabricated Shrouds of Aero-Derivative Power Turbine for Marine and Industrial Applications
Authors: Katti Srinidhi , Colantoni Simone , Tripoli Girolamo
Published: January 2020

Gas Turbine shroud is a static component, which forms the outer flow path surface and sealing clearances to turbine blade tip. It also protects the casing from hot gases ingestion and radiation. Shrouds are segmented circumferentially to accommodate the large thermal gradients. The sealing between adjacent segments and the hook clearances play an important role in controlling hot gas ingestion and loss of efficiency. Heavy duty engine shrouds are typically bulky and machined from either forged ring or investment casting. They have tight tolerance-controlled hooks and hence controlled clearances with casing. It incorporates intersegment seals to control leakages between adjacent segments. On the other hand, Aero-derivative shrouds are typically thin and sheet metal fabricated. Tight tolerance control is not possible in sheet metal hooks and use of intersegment seal is also not feasible in these thin structures. Hence both the design features and approach to address sealing criteria will be different. In this article, it presents the challenges like manufacturing constraints and life requirements and the optimization study that was performed to meet the sealing criteria considering these challenges.
Exergy Analysis of a Combined Gas Turbine and Organic Rankine Cycle Based Power and Absorption Cooling Systems
Authors: Nondy Joy , Gogoi Tapan Kr.
Published: January 2020

In this paper, a combined power and cooling system is thermodynamically analyzed. The system consists of a natural gas-fired gas turbine (GT) plant integrated with a heat recovery steam generator (HRSG), two steam turbines (STs), one organic Rankine cycle (ORC) and two absorption cooling systems (ACSs). With certain given input parameters, the GT plant produces net power of 36.06 MW, the two STs contribute 17.07 MW while from the ORC, 7.18 MW of net power was obtained. From the steam-operated ACS-I, a net 10.36 MW of cooing could be produced. Again, from the GT exhaust operated ACS-II, it was possible to generate additional 3.37 MW of cooling. From exergy analysis, it was found that the total irreversibility was the highest in the GT cycle with a net contribution of 180.412 MW followed by 4.178 MW from the HRSG, 3.561 MW from the ORC, 1.743 MW from ACS-I, 1.186 MW from ST-I, 0.812 MW from ACS-II, 0.175 MW from ST-II. The exergy efficiencies of the GT cycle, ORC, ACS-I and ACS-II were found 22.00%, 65.48%, 18.95% and 14.4% respectively. Regarding the power and cooling output, it can be concluded that these results are specific to the selected operating parameters. Further investigation is required, where, other similar configurations may be considered to make a final comment on the suitability of the proposed configuration from energy output and economic point of view.
Online Automatic Degradation Diagnosis of Gas Turbine Bearings Based on Unsupervised Machine Learning
Authors: Kakati Pallabi , Dandotiya Devendra , Savanur Rajendrakumar
Published: January 2020

The bearing prognostic analysis plays a critical role in improving the reliability of any rotational engine. In data-driven methods, used in such bearing prognosis, real time bearing vibrational data can be acquired from a set of sensors. In literature, many supervised learning techniques have been proposed to analyze this data. However, the labelled training data required for such a supervised technique is not always available in real life. Therefore, in this work, an unsupervised learning technique based on adaptive resonance theory 2 (ART2) has been used for bearing vibrational signal analysis. The benefit of this method is that no separate training is required for the prognosis purpose. The gas turbine is studied in this work is a GE MS 3002 used in natural gas transportation in Algeria. This method is used to study the bearing vibrational signal emitted at the high-pressure turbine side. The use of online method helps us updating the model, as new observations are available. This method also offers better performance under noisy environment.
Advanced Models for Fatigue Life Estimation of Combustor Components for Gas Turbine Application
Authors: Sivarama Iyer Dileep , Chandran Pillai Nikhil
Published: January 2020

Modern day combustors operate at very high temperatures which are close to combustor material softening temperatures. At the same time, to meet stringent emission legislations there is a strong drive to improve upon the rich burn combustor technology or shift to advanced lean burn combustor technologies. One of the key driver to improve emission is to save the cooling air budget and use the saved air for primary combustion but this approach would require more advanced and efficient cooling techniques. Fan shaped effusion cooling technology is a very promising technique as it offers high film cooling effectiveness. However, complex cooling features associated with this technology can lead to higher stress concertation and localized triaxial stress state. This stressstrain field in combination with a typical gas turbine engine operating cycle makes such effusion holes highly vulnerable to the thermo-mechanical fatigue failure. Hence to ensure the safety and reliability of combustor liners with such innovative features, it is essential to have thorough understanding of the stress-strain field in the vicinity and accurate prediction of life to first crack. The biggest challenge the designers and engineers face while predicting the initiation life of a structure is selecting the appropriate fatigue damage model for an application. This is due to following reasons: (a) The scatter in fatigue life predicted using different models and experimental values are very huge (b) There is no general universal method which can predict the multiaxial fatigue life accurately for all the materials and loading conditions (c) No general consensus exits among the researchers on which model have to be used for a particular application, material, loading and geometry (d) Application level studies are seldom available on this subject, most of the studies are restricted to laboratory level specimens with very limited implications to industry. Ideally, the fatigue damage model which has to be used for a particular application has to be validated through experiments. To meet this objective, several test specimens featuring novel fan shaped hole geometries were mass-produced using state of the art laser drilling technology. All these specimens were subjected to strain controlled isothermal low cycle fatigue test and the cycles to crack initiation was monitored using potential drop method. Six different multiaxial fatigue damage models (which can be used in low cycle fatigue regime) viz. Walker model, Smith Watson and Topper model (SWT), Fatemi Socie model (FS), Wang and Brown model (WB), Shang model (SW) and Xu model were selected and the life estimated by these models were compared with the experimental values. From the study it is observed that Xu model in which the damage parameter is built using the concept of shear strain energy looks most promising for this application.
Estimation of the Hydraulic Losses in the Inlet Shaft of a Land-Based Gas Turbine
Authors: Baturin Oleg V. , Kolmakova Daria A. , Krivtsov Alexander V. , Popov Grigorii M. , Volkov Andrei A.
Published: January 2020

The paper presents the results of numerical simulation of air flow through a modernized variant of the inlet filter unit (IFU) of the gas compressor unit GPA-Ts-16. A feature of the IFU design is that to reduce the load on the filter unit, it is proposed to be as compact as possible, which determines its complex shape.

The goal of the study is to study the hydraulic losses and to develop the measures to reduce them, since it is found that every 100 Pa of losses in the inlet unit increases the consumption of fuel gas by 2.5 kg/h or reduces the engine power by 10.5 kW.

Calculations of hydraulic losses in IFU are carried out for cases of absence or presence of wind with a velocity from 0 to 35 m/s, blowing from 5 main directions (0°, 45°, 90°, 135°, 180°). Studies are also carried out on the effect of the weather shield shape, presence of baffles under it, and the rack in the shaft on the hydraulic losses.

As a result of the research, recommendations are provided for designing (changing the shape) of the inlet filter unit that eventually allow to propose a design that will reduce the hydraulic losses in IFU by 15% relative to the originally suggested variant.
The Concept of a Multi-Level Optimization Model of the Centrifugal Compressor Workflow
Authors: Popov Grigorii M. , Egorov Igor , Marchukov Evgenii , Volkov Andrei A. , Baturin Oleg V.
Published: January 2020

The paper presents the main ideas of the virtual test bench concept for rapid obtaining of the reliable characteristics of compressors based on a multi-level mathematical model with a two-step identification using data obtained from mathematical models with a high order of accuracy. One of the possible identification algorithms and the results of its successful testing are given on the example of a centrifugal compressor stage developed and tested at NASA.
A Comprehensive Analysis of the Fiber Laser Application in Cleaning Process of Corrosion Layers for Iron-Based Samples
Authors: Shelar Mayur , Bawankar Kaushik , Madake Shailesh , Dhamangaonkar P. R.
Published: January 2020

This paper describes the comprehensive review of the gradual layer removal of reactive corrosion products from Iron sample to establish the methodology for less intrusive and exacting laser cleaning approach. Effects of laser radiation on substrate, factors affecting the efficiency of graffiti removal and laser parameters such as wavelength, focal length, pulse duration effect, speed, power constant, line space and laser pattern are investigated. Nano-second pulse fiber laser, operating in the near-IR at a wavelength of 1064 nm and power capacity of 30W was used in the study. The laser system was coupled via computer with EzCAD 2.9.9 UNI, a vector graphic editor, with a CAD-like capability that enables users to perform rapid, precise and complex surface scanning treatments in a repeatable way. A series of laser cleaning studies has been performed on corroded iron reference samples along with analyzing the effects of various parameter changes on the corroded surface using Alicona 3-D surface analyzer. Chemical composition, microscopic analysis and oxide content test for the various layers of sample is been determined with SEM. The results obtained from various tests are providing reliable base to understand laser cleaning mechanism and their effect on different laser characteristics.
Effect of Guide Vane Fillets on Wave Energy Harvesting Impulse Turbine
Authors: Maurya Gautam , Das Tapas K. , Dudhgaonkar P. V. , Samad Abdus
Published: January 2020

Oscillating water columns (OWC) are widely used devices for the extraction of wave energy through self -rectifying impulse air turbines. To improve the performance of any turbo-machinery, guide vanes (GV) play an essential role in deciding turbine characteristics in terms of efficiency and torque. The concept of filleting is used in the GVs of bidirectional impulse turbine (BDI) with five different types of GV fillets for different radii, and the performance was analyzed. The numerical simulation was done using the commercial code ANSYS CFX 16.2, which solves the three-dimensional Reynolds-Averaged Navier-Stokes equation by finite volume explicit Runge-Kutta scheme with the k-ω SST closure model. There is a close agreement between the experimental and the numerical model. The detailed flow physics of filleted GVs have been included in the present work, and it was found that the efficiency increases at higher flow coefficients.
Studies on the Characteristics of Three-Inline Non-Premixed Turbulent Oxy-Methane Flame Jets
Authors: Jana Tamal , Kaushik Mrinal
Published: January 2020

In the present study, the characteristics of three-inline non-premixed Oxy-Methane turbulent flame jets, with Methane jet at the center and two Oxygen jets on either side, are computationally investigated. For all the jets, the velocity is varied from 10.13 m/s to 108 m/s. It is found that, in the presence of central jet, the mixing of lateral jets are delayed further downstream. In contrast, the central jet diffuses at a faster rate. At far-field locations, all the jets merge with each other and form a single jet, which can be seen from the uniformity of the radial velocity distribution. The turbulent intensity is found to be more at the jet periphery, where jets interact with the surrounding fluid. The temperature of the flame is found to be higher at the periphery of the methane and the oxygen jets, due to the existence of most appropriate equivalence ratio. Also, the flame lift-off height is found to be increasing with the jet velocity. The concentration of methane is reduced along the streamwise direction due to the penetration of combustion products towards the jet centerline.
Leakage and Windage Heating in Stepped Labyrinth Seals
Authors: Nayak Kali Charan , Kandaswamy Nomesh P. , Faheemulla Syed
Published: January 2020

Stepped labyrinth seals are used in multiple locations in the gas turbine with the intent to reduced leakage compared to straight labyrinth seals. However the selection of geometric factors in stepped labyrinth seals is critical to allow lower leakage in its operating envelope. Particularly the step height and axial position during the running condition play a vital role. The influence of these factors on the leakage, swirl development and windage heating in stepped labyrinth seal has not been thoroughly investigated in the previously published work. This paper focuses to study above effects with numerical simulations in a smooth four-fin stepped labyrinth seal. Specifically, a 2D axi-symmetric computational fluid dynamics (CFD) model is developed utilizing commercial finite volume-based software incorporating the standard k-ε turbulence model. Using this model, a broad parametric study is conducted by varying step height, axial position of the knife from the step, radial clearance and pressure ratio for a four-teeth stepped labyrinth seal. It has been observed that the seal leakage reduces with increase in step height to pitch ratio up to 0.35 and with further increase it tails off. The axial position of the tooth has strong influence on the flow structure and swirl development in the seal pocket.
Towards Visualisation of Capacity, Bearing Thrust Load and Reaction Variation With Aerofoil Skew in a Gas Turbine
Authors: Srinivasan Karthik , Bhaumik Soumyik K. , Valliappan Lakshmanan
Published: January 2020

The requirements in the design of aerofoils for gas turbines are not limited to only meeting the aerothermal performance. A typical scenario for a turbine is to understand the impact of aerofoil skew on capacity, reaction and bearing thrust load. A means to achieve the target capacity could be by skewing the aerofoil. This, however, changes the stage reaction which in turn impacts the bearing thrust load. In the case of a multi stage turbine, the work split between the stages impacts the ratio of pressure drops and hence the contribution of the individual aerofoil rows to the overall capacity and bearing thrust load variation. This paper deals with a generic approach to visualise the variation of capacity and bearing thrust load with aerofoil skew for a stage of interest along with the Constraints that could be potentially imposed on the stage.

This methodology provides a useful mapping between parameters which are directly under the aerodynamicist’s control (i.e. aerofoil skew) to module- and system-level behaviours (i.e. capacity, bearing thrust load). It thereby allows informed choices to be made throughout the design process which deliver the turbine aerodynamic performance targets whilst respecting wider system-level constraints. Suitable optimisation within this design space will yield a design that is fundamentally robust to small deviations in skew angle. Additionally, qualitative variation of the gas path static pressure and reaction based on aerofoil skews are explained pictorially to facilitate the understanding.
Comparison of Showerhead Jet Impingement Configurations on Leading Edge of a Gas Turbine Blade
Authors: Singh Alankrita , Prasad B. V. S. S. S.
Published: January 2020

Anemometry measurements are made on three novel, equilaterally staggered showerhead cooling configurations of jet impingement, for the leading edge of a gas turbine blade. In all the configurations, there are five jet impingement tubes in the form of a showerhead, wherein the central jet is circular and the remaining four neighboring jets have either circular or ±45° chamfer at one of its end. Flow characteristics of these jet configurations are analyzed by determining the mean velocity and the turbulent intensity of jets. The differences in the flow characteristics of these arrangements occur due to the changes in jet velocity profile and jet-to-jet interactions. The turbulent intensity is primarily responsible for augmentation in heat transfer of the test section. The uniform cooling of test section is represented by an “uniformity index” a high value of which is desirable for material durability. The Nusselt number is correlated with Reynolds number and turbulent intensity for all the three configurations.
Experimental Analysis of Vortex Induced Vibration in the Bladeless Small Wind Turbine
Authors: Thomai Micha Premkumar , Kharsati Lasoodawanki , Rama Samy Nakandhrakumar , Sivamani Seralathan , Venkatesan Hariram
Published: January 2020

Vortex-induced vibration is one of the predominant fundamental concepts for forced oscillation which attracts considerable practical engineering application for energy conversion. In this work, an oscillation of a mast arising as a result of wind force is utilized for energy conversion. The paradigm for energy conversion from vortex-induced vibration in the mast is the bladeless wind turbine. It consists of a rigid mass known as a mast, fixed in the spring of stiffness (k) and allowed to oscillate along the direction of the flow. In this work, four different types of mast have been fabricated and tested. The first is uniform tapered hollow conical mast (MAST1), the cross-section of the second is uniform tapered plus symbol (MAST2), the third is uniform tapered inversed plus symbol (MAST3) and the fourth is uniform tapered simple rectangular cross-section (MAST4). All the masts were fabricated using fiber carbon. The experiments were conducted in a versatile small wind turbine testing facility of Hindustan Institute of Technology and Science, Chennai. This test facility contained an open jet wind tunnel with variable frequency drive and other measuring instruments. The vibration sensor was located in the mast where it experienced a large oscillation in a free stream. In this experiment, an increase in wind velocity led to a terrible change in the amplitude of vibration. A vigorous oscillation was experienced in this mast at this critical frequency, when the natural frequency of the mast was synchronized with the frequency of the vortex shedding and the frequency of the oscillation of the mast. The total force in this oscillation was a summation of the body force due to the mass of the mast and vorticity force that is mainly which was the result of the shedding of the vortices. In this work, extensive studies have been carried out for Reynolds number ranging from 2.5 × 105 to 5.0 × 105. The mast length to diameter ratio of 13 was exposed to various speeds of wind and response was measured. The occurrence of the maximum oscillation in a simple rectangular mast was seen where vortex shedding due to the bluff body was large for constant mass and spring stiffness. The frequency of the oscillation at maximum amplitude of the rectangular cross-section mast was equal to the natural frequency, due to vortices shedding at critical velocity. This demonstrated the appropriateness of the simple rectangular cross-section for harnessing the low rated wind energy and its suitability for renewable energy conversion in the small bladeless wind turbine.
Thermodynamic Analysis and Performance Enhancement of Air and CO2 Based Compressed Gas Storage Systems
Authors: Dahiya Abhishek , Bhattacharya Jishnu , Banker Nitin D.
Published: January 2020

Due to the depletion of fossil fuels and their adverse effects on the environment, there is a need of hour to shift towards the renewable energy resources. However, the most promising renewable resources such as wind power and solar power are intermittent in nature. Thus, a sustainable shift requires economical and efficient energy storage systems. Use of batteries is the widely accepted storage systems for such resources and significant research work has been carried out in last few decades to improve the cycle life of batteries but they are still unsuitable for large scale systems and disposal of discarded batteries is also a major environmental concern. In view of this, researchers found compressed gas energy storage (CGES) system as one of the potential alternatives to store renewable energy at large spatial and temporal scales. The current study provides a comparison between air and carbon dioxide (CO2) based CGES systems from a thermodynamic standpoint. In an effort of improving efficiency of system, it is proposed to supply additional heat via renewable resource to CO2 based system before the expansion of gas in the turbine. The performance comparison of six different systems has been carried out using first and second law efficiencies.
Effect of Partial Texture on the Hydrodynamic Performance of Meso Scale Air Bearings for Mesoscale Turbo-Machines
Authors: Hingawe Nilesh , Bhore Skylab
Published: January 2020

In this paper, the hydrodynamic performance of surface textured meso scale air bearing is evaluated. The effect of texture position is investigated for circular shaped texture. Partially textured zones are modeled along the circumferential direction of the bearing. For this, numerical simulation is carried out using COMSOL Multiphysics 5.2 software. The compressible Reynolds equation is solved using the finite element method for a thin film model. In comparison with plane bearing, the significant improvement in load capacity is observed for textured bearing. Full texturing has obtained 12.80% more load capacity than the plane bearing. Among different partial texture positions, the convergent zone (0°–180°) showed the most promising result. It has obtained 14.02% and 1.25% more load capacity than the plane and fully textured bearings. Moreover, the texture position in the bearing is found to be sensitive. However, surface texture at the outlet of active pressure zone is found to be ineffective for improving load capacity of the bearing.
Numerical Simulation and Experimental Validation of Frequency Based Fault Detection and Localization in a Planetary Gearbox Under Dynamic Condition
Authors: Venkataram Nithin , K. Bhagavan Harish , Cadambi Rahul M. , R. Rao Arun
Published: January 2020

The planetary gearbox is often susceptible to faults under dynamic condition. Most of the literature assumes that gearboxes are free from defects. But in real-time working condition these assumptions are not accurate. Therefore the challenge lies in identifying and localizing a fault in planetary gearbox under dynamic condition. In this paper, the focus is on modelling and simulation of a fault in a planetary gearbox and validate the same with experimental tests. A planetary gearbox is modelled as per DIN standard and simulated for time and frequency domain signals. On comparing a fault free and fault induced frequency domain signals, a small peaks are observed on either side of the mesh frequencies, indicating the presence of a fault in the planetary gearbox. These peaks around the mesh frequencies are used to localize the fault in a planetary gearbox. Simulation results are validated with the experimental test results of the planetary gearbox under dynamic conditions. Similar trend is observed in simulation and experimental results.
On Effect of the Flare Angle on the Behaviour of the Flow Field of Twin-Radial Swirlers/High Shear Injector
Authors: Kumar Sonu , Chaudhuri Swetaprovo , Basu Saptarshi
Published: January 2020

The swirl flow in gas turbine combustor plays a major role in flame stabilisation and performance of engine. Since the swirl flow is very complex and boundary sensitive phenomena, it is difficult to interpret it properly. High shear injector is being used now a days in modern gas turbine combustor to generate the swirl flow and achieve better fuel atomisation in the combustion chamber. High shear injector accommodates a series of swirlers (primary and secondary) with a diverging flare at the exit and fuel nozzle mounted at the centre of the swirler.

In the present study it is tried to understand the influence of the flare angle on the non-reactive flow behaviour of the swirling spray flow-field generated through counter-rotating high shear injector. To perceive the influence of flare angle on the flow topology of the spray flow-field generated by a high shear injector, seven different flare half angles (β): 40°, 45°, 50°, 55°, 60°, 65° and 70° respectively were selected as a geometrical parameter to conduct the experiments. High-Speed Particle Image Velocimetry (HSPIV) technique was employed to perceive the topological structure of the spray flow field, mean and instantaneous behaviour of the velocity fields respectively. For all the cases mass flow of air and liquid (water) were kept constant. It was observed that with change in flare angle the size of the CTRZ, mean velocity and turbulent behaviour were also changing. Here the size of CTRZ is represented in terms of nondimensional radial width (W/Df) and height (H/Df) of the recirculation zone. The experiment was conducted without flare, initially and then subsequently with flares. It was found that both the radial width and the height of the recirculation zone were smallest for without flare case. With increase in flare angle the radial width and height of the CTRZ increases initially up to 60° flare angle and afterward decreased. The experiments made clear that flare angle has strong effect on the spray flow-field.
Application of Data Analytics in Gas Turbine Engines
Authors: Taluru Danteswara Rao , Allabanda Rajendra Prasad Uppara
Published: January 2020

In recent years, Aerospace technology has seen a paradigm shift towards Data analytics. Design, manufacturing, aftermarket and operations found importance of data analytics in reducing cost. Manufactures are developing Data Analytic based tools which help in optimizing their processes and reduce lead time. Engine, aircraft manufactures along with airliners are working together to improve customer experience. This paper, covers topics related to engine manufactures point of view. Engine manufactures can apply data analytics in concept initiation, concept optimization, preliminary, detailed and validation phases. Manufactures can optimize supply chain management using data analytics. Major gas turbine manufactures are persistent to enhance intelligence in aerospace product life cycle. Data analytics in aerospace engineering also helps in making predictions based upon descriptive patterns from huge data. Since, the aircraft industry is expecting a seven-fold increase in air traffic by 2050. The future demand of aircraft engine production would drive industries to adopt to big data in helping decision making and dynamic production capabilities. This paper helps in identifying different data analytics application in gas turbine product life cycle. Specifically in aero thermal discipline, which would help in increasing efficiency, optimizing design and result in reducing cost. This paper takes the reader through the application of gas turbine as a systematic and concise article. The future scope of the paper would include a test case explaining the application more in detail using data analytics.
Labyrinth Seal With Variable Height Teeth Tips for Efficient Leakage Control
Authors: Chougule Hasham , Naik Abhay , Qizar Mohd.
Published: January 2020

A modification of a conventional straight tooth labyrinth seal with variable tooth height is proposed. The baseline and modified labyrinth seal teeth with solid land are examined by three-dimensional CFD numerical modeling of the flow field and evaluated for predicting the leakage through the seal during the engine operation. Stocker’s [1] static labyrinth seal experimental data is used to validate the CFD methodology used in this paper. The baseline and the proposed modified design [2] — “Labyrinth seal with variable tooth heights” are numerically studied with solid lands and evaluated to measure the reduction in leakages. The objective of this study is to provide an improved sealing effectiveness by restricting the leakage flow and controlling the seal leakage during the operation of the engine. In this study, a conventional straight-through four-tooth labyrinth seal with solid land is used as the baseline model. It is first evaluated at different unworn constant radial gaps — between the teeth tips and solid land. In the proposed modification, the height of the intermediate teeth of the baseline four-tooth are varied. The teeth heights are designed in such a way that intermediate longer teeth form a very small or tighter radial gap at start of operation. The shorter ones are designed based on the expected wear groove/rub depth considered by the seal designer.

Results indicate that the proposed modification — Variable height teeth tips, reduce the seal leakage by over 50% compared to the baseline. The advantage of this modified design over a baseline seal is that at unworn or worn conditions, the teeth tips always forms a considerable tighter radial gap when compared with baseline seal. The achieved sealing is such that during engine operation of the seal, even if the seal gets worn, the overall leakage is significantly reduced.
Dynamic Parameters Estimation and Fault Identification From Random Response of Rolling Element Bearing in a Rotor Bearing System
Authors: Kumar Pankaj , Narayanan S. , Gupta Sayan
Published: January 2020

This paper presents a procedure for determination of dynamic properties of rolling element bearing by using the vibration signals picked up at the bearing caps. The rotor-bearing assembly is idealized as Duffing oscillator and random vibration signals modelled as exponentially correlated (Ornstein-Uhlenbeck) colored noise. Expressing the excitation as a first order filtered white noise enables the direct formulation of the 3D-Fokker Planck (FP) equation for system response through the Markov vector approach. Closed form solution of the stationary FP equation is derived. Subsequently the response statistics of experimentally obtained random vibration signal are processed through the closed form solution of the FP equation as the inverse process of parameters estimation from the measured response. Further, the dynamic behavior of rigid rotor-bearing system is investigated under combined excitation of white noise and harmonic forces arising due to rotor unbalance force. The effect of system nonlinearities, stiffness, damping and unbalanced excitation force on the dynamic response are investigated using the bifurcation plot. For assessment of structural degradation of bearings, a novel entropy based approach is developed. Experimental studies on roller bearing are carried out to demonstrate the effectiveness of the proposed approach.
Energy and Exergy Analysis of a Gas Turbine Power Plant Integrated With Vapor Adsorption Refrigeration System
Authors: Agarwal Sanchit , Gupta Darshika , Dandotiya Devendra , Banker Nitin D.
Published: January 2020

In the step towards the utilization of waste energy of Gas Turbine (GT) power plant exhaust gas, researchers have imposed adsorption refrigeration system over the absorption refrigeration due to several positive advantages. In the reported work, the system was analyzed based on first law efficiency. However, combining heat and work together for an evaluating system using first law efficiency would not provide a true picture of the performance of the system, whereas second law efficiency shows various irreversibilities associated with each component of the system and helpful in obtaining the optimum conversion of energy. In view of this, the presented paper studies performance analysis of GT power plant incorporated with the adsorption refrigeration system. Based on the parameters such as energy and exergetic efficiencies, cooling to power ratio and exergetic specific fuel consumption are considered for the system performance evaluation.
A Study of Flow Behaviour in Radial and Mixed Flow Turbines With Variable Nozzle Vanes for a Turbocharger
Authors: Kannan Ramesh , Prasad Bhamidi , Koppa Sridhara
Published: January 2020

A mixed flow turbine with variable nozzle vanes is developed along with its radial counterpart for the wheel size of about 30 mm, suitable for turbocharger of 1.5 lit. engine capacity. In order to understand the flow behaviour inside the turbines, computational fluid dynamics studies are conducted for both the radial and mixed flow turbines. Flow through the turbine stage is discussed with velocity distribution in the meridional plane. In addition, the loss coefficients for the nozzle vanes and turbine wheel are estimated. At nozzle vanes opening of 50% mass flow parameter and for the turbine expansion ratio of 1.5, the flow velocities at the exit of the nozzle vanes are found to be about 120 to 170 m/s for the radial flow turbine and 150 to 180 m/s for the mixed flow turbine. Higher level of uniformity in flow is also observed for mixed flow turbine stage compared to the radial. The maximum Mach number is observed on the middle of the turbine wheel, and the same is less than unity for both the turbines. Both the nozzle and rotor loss coefficients for mixed flow turbine are lower than the values observed for the radial flow by about 6% and 15% respectively.
Effect of Various Trench Designs on Axial Compressor Blade Tip Aerodynamics
Authors: Ashok Ashwin , Sidhartha Patur Ananth Vijay , Sivadasan Shine
Published: January 2020

Tip clearance of axial compressor blades allows leakage of the flow, generates significant losses and reduces the compressor efficiency. The present paper aims to discuss the axial compressor tip aerodynamics for various configurations of tip gap with trench. The various configurations are obtained by varying the clearance, trench depth, step geometry and casing contouring. In this paper the axial compressor aerodynamics for various configurations of tip gap with trench have been studied. The leakage flow structure, vorticity features and entropy generations are analyzed using RANS based CFD. The linear compressor cascade comprises of NACA 651810 blade with clearance height varied from 0.5% to 2% blade span. Trail of the tip leakage vortex and the horseshoe vortex on the blade suction side are clearly seen for the geometries with and without casing treatments near the stalling point. Since the trench side walls are similar to forward/backing steps, a step vortex is observed near the leading edge as well as trailing edge of the blade and is not seen for the geometry without the casing treatment. Even though the size of the tip leakage vortex seams to be reduces by providing a trench to the casing wall over the blade, the presence of additional vortices like the step vortex leads to comparatively higher flow losses. An increase in overall total pressure loss due to the application of casing treatment is observed. However an increase in stall margin for the geometries with casing is noted.
Simulation of CO Emission in Primary and Secondary Zone of a Small Gas Turbine Combustion Chamber Using CFD and Reactors Network
Authors: Zubrilin Ivan A. , Gurakov Nikita I. , Semenikhin Alexander S. , Kolomzarov Oleg V. , Matveev Sergey G. , Anisimov Vladislav M.
Published: January 2020

In this paper the influence of various parameters of the primary and secondary zones of a small-sized combustion chamber on its environmental characteristics was studied. The study of the environmental characteristics of the combustion chamber was carried out in two ways. The first method consisted of two steps. The first step was a 3D simulation of combustion processes using FGM combustion model. The second step was based on results of the first step using reactors network implemented in the ANSYS Fluent 18.2 software. The construction of the reactors network in this approach occurred automatically according to a temperature and mixture fraction. The number of reactors in the result was about 500. The second method was a simple model of a reactors network in which the primary zone was simulated by a perfectly stirred reactor, and the secondary zone was a plug flow reactor. Methane was used as a fuel. The influence of the residence time of the mixture and fuel-air equivalence ratio in each zone on the emission of CO and NOx at the combustion chamber exit was studied. The residence time and fuel-air equivalence ratio for the first method were changed using the design parameters of the combustion chamber. For a simple reactors network, these parameters are set as input data, so this method can be used at the preliminary design stage. As a result of the work, a method was obtained that allows to find the parameters of the primary and secondary zones of the combustion chamber in order to minimize pollutant emissions at the preliminary design stage.
Investigation of a Variable Geometry Turbine Nozzle for Diesel Engine Turbochargers
Authors: Srivastava Anuj , Kumar Kuldeep , Banda Ganesh
Published: January 2020

High power demand, emission regulations, high efficient design are the prime requirement for the design of turbochargers. VGT (variable geometry turbocharging) is most widely used and explored compared to other available options to deal with today’s market. VGT turbochargers offers several potential benefits when compared to fixed geometry turbochargers, like increased transient response, wide operating range, improved torque characteristics, boost pressure recovery and better fuel economy. In this paper performance variation of compressor and turbine viz, — Pressure ratio, mass flow, and efficiency, and throat area are optimized to reach to the operating point of the engine. Different vane angles (0, +4°, +7°, +10° & +15°) are studied to understand the variation of transient turbine response. Authors also discussed the mechanical conceptualization of the VANT (Variable area nozzle) in thought of having great impact on the performance.
Liquid Atomization in a High-Speed Slinger Atomizer
Authors: Chakraborty Arnab , Sahu Srikrishna
Published: January 2020

The present research aims to investigate the liquid atomization process in a slinger atomizer test rig that houses a high-speed motor which allows high rotational speed of the slinger disc. Instead of delivering the liquid directly on the slinger disc, which is commonly reported in the literature, a stationary manifold was designed that receives the liquid from the pump and supply multiple liquid jets that impinge on the rotating slinger disc. The liquid jet breakup process was visualized using front light illumination technique. All experiments were performed using water as the working fluid and under atmospheric conditions. Four different water flow rates, ranging from 0.2 lpm up to 0.8 lpm were considered. The rotational speed of the slinger was varied from 5000 rpm up to 30000 rpm, which has been rarely reported in the past. The paper reports a comprehensive study on the differences in the liquid breakup modes due to higher liquid flow rate for the same rotational speed and vice-versa. Mostly the liquid was found to attach to the side of the slinger holes that is opposite to the direction of rotation indicating the strong influence of Coriolis forces on the liquid flow within the slinger and hence the atomization process. The droplet size in the spray was measured using the Interferometric Laser Imaging for Droplet Sizing (ILIDS) technique.
Experimental Study of Flow Field Effect on Spray and Flame Structure in Swirl Stabilized Combustor
Authors: Murugan Raju , Sellan Dhanalakshmi , Kolhe Pankaj S.
Published: January 2020

The spatial distribution of spray plays a key role in liquid fuel combustion, which dictates the local mixture fraction and the flame temperature distribution in gas turbine engines. The swirling flow creates further decomposition of the spray droplets in liquid fuel gas turbine engine, which increases the surface area of the droplets. Turbulent mixing due to the swirling flow is essential for preheating of unburned products and flame holding in the combustor. A lab-scale swirl stabilized liquid fuel combustor was designed and fabricated with the geometric swirl number (SN) of 1. Combustor flow geometry involves internal spray from flow blurring twin-fluid atomizer, surrounded by swirling airflow which is confined with co-flow air to provide full optical access. At constant spray operating conditions, the swirl Reynolds number (Re) is increased whereas co-flow velocity was maintained constant at 0.4 m/s. An experimental study was carried out to understand the effect of Reynolds number on the aerodynamic structure of airflow, the spatial distribution of spray structure and kerosene flame structures using Particle Image Velocimetry (PIV) and direct imaging. The experimental results show that the flow structure and spray spreads radially with the increase in swirl Reynolds number and the corresponding core spray height decreases, which were evident from flame images.
Enclosure Phenomenon in Varying Forced Flow Convection
Authors: Bhatia Ribhu , Supriya Dash Sambit , Malhotra Vinayak
Published: January 2020

Systematic experimentation was carried out on forced convection heat transfer apparatus under varying non-linear flow conditions to understand the energy transfer as heat, with the purpose of enhancing performance of numerous engineering applications.

Plate orientations, types of enclosures (solid, meshed, perforated), flow velocity variations etc. are taken as governing parameters to effect convective heat transfer phenomenon which is perceived as deviations in value of heat transfer coefficient. RV zonal system is utilized to simplify the fundamental understanding of heat transfer coefficient variation with surface orientation under varying flow field. The objectives of this work are as follows:

1) To establish relative effectiveness of forced convective heat transfer under varying flow field.

2) To investigate the implications of varying shapes and sizes of perforations on confined forced convective heat transfer.

To understand the controlling mechanism and role of key controlling parameters.