bluuebunny/crossref_metadata_2025_split huggingface dataset:
Modelling, Analysis and Flight Testing of a Military Turbofan Engine Under Windmilling Conditions
Authors: Balaji Budharaju , Om Prakash Raj N. , Padwale Mahesh P. , Ravishankar G. P. 
Published: January 2020

Abstract
Flight testing of a military low bypass turbofan engine involves multitudes of tests to ensure the Engine - Aircraft compatibility across the flight envelope. One of the safety critical tests is to conduct In-Flight restart of the engine. Detailed planning and careful execution is mandated for a single engine aircraft. Accurate modelling of sub-idle performance characteristics of the engine during windmilling conditions enables better prediction of engine behavior during in-Flight shutdown and restart. Typically, Engine manufacturer provides a Performance Cycle Deck (PCD) to predict and assess the performance of the engine across the flight envelope for all throttle positions. However, the PCD does not include sub-idle behavior. The present work focusses on developing a torque based engine behavior model which enables prediction of time dependent fan and compressor characteristics during sub-idle operations. The proposed model is divided into two parts. The first part deals with deceleration characteristics during engine shut-off and spool down, and the second part deals with the acceleration characteristics during spooling up and engine restart. In-flight spool-down (a quick relight without windmilling) restart data obtained through flight tests was used to validate the present model. The model is intended to be used for future flight tests which include windmill restarts under various operating conditions. The model is expected to accurately predict the correlation between aircraft speed and engine windmilling rotor speeds for arriving at a windmill restart envelope for the aircraft.
Performance Evaluation of a Gas and Steam Turbine Based Cogeneration Plant: A Case Study
Authors: Gogoi Tapan Kr. , Gautam Uddipta 
Published: January 2020

Abstract
In this study, performance of a combined power and cogeneration plant is evaluated. The plant is basically the captive power plant (CPP) of Numaligarh Refinery Limited (NRL), located in Golaghat district of Assam, India. The plant consists of a gas turbine (GT) plant as topping and a steam turbine (ST) plant as bottoming cycle. In the CPP, there was also provision for extracting steam from the ST at two different points for process heating in the refinery. CPP operational data regarding pressure, temperature and mass flow rates were collected from the refinery. It was observed that although the performance related data (the GT and ST power outputs) were available but the air flow rate (AFR) of the GT plant was not known. Therefore, this study aimed first at estimating the unknown AFR using an inverse method for which a differential evolution (DE) based optimization algorithm was used. Next, it was attempted to estimate both the AFR and fuel flow rate (FFR) simultaneously assuming that suppose the FFR is also not known. The objective was to find out better combinations of FFR and AFR over the base case corresponding to the single parameter (only AFR) estimation. The performance of the CPP was evaluated with the estimated AFR corresponding to the base case and also with the one of best FFR/AFR combination out of 25 such combinations obtained from simultaneous estimation. For the base case, the overall energy and exergy efficiency of the CPP were found to be 15.39% and 15.37% respectively. However, if the process heating is also taken into consideration, then these efficiencies in cogeneration mode increase to 21.04% and 21.0%. But with the selected best FFR/AFR combination obtained from simultaneous estimation, the overall energy efficiencies of the combined and the cogeneration plant could be improved from 15.39% to 17.68% and from 21.04% to 24.16% respectively. This has also reduced the total plant irreversibility from 183.729 MW to 152.955 MW. It was found that the maximum exergy destruction occurs in the combustion chamber (58.62%) of the GT plant followed by the utility boiler (29.37%) and heat recovery steam generator (3.76%). The results confirmed lower efficiencies for the plant indicating opportunities for further performance improvement particularly in the GT plant. NRL must go for other performance diagnostic tests which might give some actionable recommendations for restoring the lost performance. In the conclusions, other possible causes of low performances are discussed and necessary recommendations have been provided.
MBSE Model on Gas Turbine Tip Clearance Control
Authors: Kulkarni Guruprasad , Price Sebastian 
Published: January 2020

Abstract
Model Based System Engineering (MBSE) is a systems engineering methodology to understand the customer needs and create functional model to capture requirements and develop design definitions. This paper represents the MBSE activity carried out on Turbine Tip Clearance Control (TCC) System for a Trent XWB Engine. TCC is a critical system of an Aircraft engine, whose function is vital throughout the engine life. This is a complex system as both mechanical and control systems need to interact seamlessly to meet its operational requirement. The key accomplishment of this study is, abstracting of complex mechanical system into functional model and connecting it to functional model of Controls in MBSE environment. This is done for a system that meets the standards of very safety critical and highly regulated industry of Civil Aircraft Engines.
The software used for building requirements models for TCC is Capella. Capella is open source free software built on Architecture Analysis and Design Integrated Approach (Arcadia) frame work. This framework extends and simplifies SysML. The advantages of this frame work over SysML are explained in [Ref. 1]. The Arcadia frame work is well suited to capture the complex systems involving multiple disciplines along with Mechanical systems as explained in [Ref. 2].
This paper presents a detailed study performed on product system level requirements and captures both functional and non-functional requirements such as operational and safety requirements. In the Arcadia framework this is represented at system analysis level. Further studies capture the logical and physical architecture which is representative in nature.
Automatized 3D-Scanning Application for the Virtualization of Large Components
Authors: Mönchinger Stephan , Schmidt Marvin M. , Dreßen Sebastian , Wissmann Patrick , Stark Rainer 
Published: January 2020

Abstract
Many of the large components of modern gas turbines are cast, resulting in rough surface profiles, which have to be machined to achieve the component’s final state. As there are high deviations in casting components, the real geometry does not meet the ideal model dimensions and is known neither to the supplier nor to the customer. While manual 3D-scanning processes, heavily depending on the operator’s qualification, get more attention, conventional means are still the basis for quality assurance of such parts.
Although significant time reduction can be reached by automated scanning, there is still a low variety of corresponding applications for large components on the market. Flexible systems are an approach for further development as most of the manufacturers handling large components already have and use machine tools for the processing of their components.
The designed and implemented prototypical system allows the acquisition of a large component’s surface with only a few manual inputs prior to the actual scanning procedure. It can be used with existing machining tools, allowing an easy implementation for different use cases of a pre-manufacturing scan, e.g. for CAM planning. The application is implemented in a small software tool that can be adapted to other machines with low effort. The implementation has been demonstrated in a real manufacturing environment with typical environmental conditions in the shop floor. The prototypical application has been built mainly with existing components.
Following the V-Model, each domain has been investigated individually followed by a complete system investigation. With a system price below 100.000€ the price is below 10% of most automated systems on the market. The presented cost efficient, low complexity prototypical system can provide early information about the product for a digital process chain in industry 4.0, enabling flexible, intuitive and easy integration.
Estimation of the Influence of the Inlet Nonuniformity on the Performance of a Fan of a Turbofan Engine
Authors: Popov Grigorii M. , Baturin Oleg V. , Novikova Yulia D. , Zubanov Vasilii M. , Volkov Andrei A. 
Published: January 2020

Abstract
The paper presents the results of numerical simulation of the effect of flow nonuniformities at the engine inlet on the working process of the engine fan. Flow nonuniformities is created by pushing the interceptor into the flow path of inlet device like as it is often done during field tests. The authors have created a numerical model capable of considering non-stationary processes in the fan using nonlinear harmonic analysis. As a result, qualitative and quantitative estimates were obtained of the influence of overlapping of the inlet duct by the interceptor on the main parameters of the fan workflow. It is shown that the more the duct is blocked, the more its parameters are deteriorated. Moreover, the deterioration is not linear, but according to the dependence of the 2nd order.
Parametric Studies on Gas Turbine Labyrinth Seal for the Secondary Air Flow Optimization at Static and Rotating Conditions
Authors: Raja Kaliraj Karthick , Yepuri Giridhara Babu , Janardanan Sarasamma Jayakumar , Kumar Kishor , Jesuraj Felix 
Published: January 2020

Abstract
Various studies have been carried out related to the labyrinth seals and reported in the open literature using the different seal arrangements at the stator-rotor seal cavity region. In the present study, numerical analysis has been carried out for the static and rotational effects of labyrinth seals at various flow and geometrical, parametric conditions for the optimized leak flow using straight and steeped seal configurations. And, an experimental data has been generated for the straight through seals, and the numerical data of the same case is validated with the experimental data. The k-omega SST turbulence model is considered with 5% turbulence intensity for the CFD analysis. At a particular seal clearance, as the number of teeth increases the leakage flow is found to be decreased. The leak flow is found to be lower with the stepped labyrinth seals in comparison to the straight through seals. The leak flow amount is found to be lower at a rotational condition in comparison to the stationary condition. From the overall results, it is observed that the stepped seal with a lower clearance at a compressor bleed air temperature and rotational conditions have shown better performance with the lower leak air mass flow.
Modified Brayton Cycle for Turbofans
Authors: Singhal Chirag , Hasan Sameer , Baig M. F. 
Published: January 2020

Abstract
In the present study, a design point analysis of twin-spool turbofan engines is carried out, considering fuel injection of Aviation Turbine Fuel (ATF) in the initial stages of the compressor instead of combustor The two-phase compression brings about intercooling in the modified Brayton cycle, by injecting the atomized fuel directly in the initial stages of axial-flow compressor. The intercooling effect results in reduction of compressor work while reinforcing the enthalpy of combustion of fuel due to change of state of fuel from liquid to vapor state. This brings about an improvement in the thrust and thermal efficiency of the modified cycle. Effect of the intercooling is investigated for different performance parameters namely Fuel flow rate ṁf Total thrust Fs, Thermal efficiency ηth, Overall efficiency ηo and Modified cycle factor MCF over the varying compressor pressure ratio (CPR).
Injecting the fuel in the 2nd stage of compression results in percentage increase of total thrust by 21.14%, MCF by 31.35%, ηo by 14.92% and decrease in Fuel flow rate ṁf by 7%. While injecting the fuel in the 5th stage of compression results in increased ηo by 17.54 %, MCF by 37.30%, total thrust by 5.68% and decrease in Fuel flow rate ṁf by 22% at a CPR = 30 and Turbine Inlet Temperature (TIT) = 1260K vis-à-vis conventional cycle. Injecting the fuel in latter stages of compressor brings about a decrease of total thrust as well as efficiency.
Effect of Process Parameters on Laser Directed Energy Deposition of Copper
Authors: Yadav Sunil , Paul Christ P. , Jinoop Arackal N. , Nayak Saurav K. , Rai Arun K. , Bindra Kushvinder S. 
Published: January 2020

Abstract
Laser Additive Manufacturing (LAM) is an advanced manufacturing processes for fabricating engineering components directly from CAD Model by depositing material in a layer by layer fashion using lasers. LAM is being widely deployed in various sectors such as power, aerospace, automotive etc. for fabricating complex shaped and customized components. One of the most commonly used LAM process is Directed Energy Deposition (LAM-DED) which is used for manufacturing near net shaped components with tailored microstructure, multi-materials (direct and graded) and complex geometry. This paper reports experimental investigation of LAM of Copper (Cu) tracks on Stainless Steel 304 L (SS 304L) using an indigenously developed LAM-DED system. Cu-SS304L joints find wider applications in tooling, automotive and aerospace sectors due to its combination of higher strength, thermal conductivity and corrosion resistance. However, laying Cu layers on SS304L is not trivial due to large difference in the thermo-physical properties. Thus, a comprehensive experiments using full factorial design are carried out and a number of Cu tracks were laid on SS304L substrate by varying laser power, scan speed and powder feed rate. The laid tracks are characterized for track geometry and porosity and the quality of the tracks are analyzed. Lower values of laser power and higher powder feed rate results in discontinuous deposition, while higher laser power and lower powder feed rate results in cracked deposits. Porosity is observed to vary from 6–45 % at different process conditions. Analysis of Variance (ANOVA) of deposition rate and track geometry is performed to estimate the major contributing process parameters. This study paves a way to understand effect of process parameters on LAM-DED for fabricating bimetallic joints and graded structures of Copper and SS304L.
Near Wake Regime Study on Wind Turbine Blade Tip Vortex
Authors: Siram Ojing , Sahoo Niranjan 
Published: January 2020

Abstract
In the present research article results on wind turbine blade tip vortex have been presented, the measurements have been done behind a model scale of horizontal axis wind turbine rotor. The rotor used for flow characterization is a three-bladed having NACA0012 cross-section, the study has been performed for low range tip speed ratio of 0–2 and wind speeds range of 3–6 m/s. The investigation has been conducted specifically to near wake regime, which is often expressed as the region of regular helical vortex structures. Although this nature of regular helical vortex pattern has always been a question of debate with respect to changes in the flow condition, rotor geometry and point of measurements. A systematic experiment was done mainly on the frequency of vortex shedding through hot-wire anemometry (HWA), and the corresponding frequency is express in terms of Strouhal number. Present article work within near wake regime includes tip vortex shedding stability analysis for different blade pitch angle and flow condition. From the systematic experimental observation, the evaluated data indicate that the Strouhal number has an incremental trend when the blade pitch angle is close to 40°, and above it inconsistency in frequency response is observed.
Effect of Liquid/Gas Density Ratio on Primary Jet Breakup of Pressure Swirl Atomizer: Experimental and Numerical Study
Authors: Michael Edin , Keerthi Santhosh Kumar , Kant Krishna , Kolhe Pankaj , Banerjee Raja , Chakravarthy S. R. 
Published: January 2020

Abstract
This work reports experimental and numerical study of primary jet breakup of a pressure swirl atomizer. Experiments were performed in a constant volume spray chamber and the spray pattern was characterized as a function of different liquid/gas density ratios which was achieved by changing the ambient pressure. The liquid/gas density ratio was varied between ≈ 102 to 103 and the axial Reynold number was maintained at 6 × 103. Diffused backlight imaging in conjunction with high speed videography was used to visualize the spray. Parameters like spray cone angle, spray breakup length and flapping frequency was estimated. Additionally, POD analysis was performed to find the sheet instability modes.
A corresponding numerical study using Coupled Level Set VOF method was performed keeping the liquid/gas density ratio of 10 and 102 to simulate the primary jet breakup using an in-house two-phase solver developed using OpenFOAM libraries. The solver was validated by following the numerical work of Fuster et al. Effect of computational mesh size on parameters like spray cone angle, breakup length was estimated.
Effects of Total Pressure Distribution on Performance of Small Size Counter-Rotating Axial-Flow Fan Stage for Electrical Propulsion
Authors: Bandopadhyay Tuhin , Mistry Chetan S. 
Published: January 2020

Abstract
Counter-rotating fan stage provides significant benefits over the conventional fan in terms of overall performance and size. For electric propulsion application, counter-rotating fan provides compactness and reduction in weight to achieve higher pressure rise with less power consumption as compared to the unducted propeller. Past literature suggests counter-rotating fans, designed with higher loading in front rotor has a flat performance map and a wider range of stable operation. This, in particular, benefits the electrical vehicle to have higher maneuver capability during operation.
The paper discusses the design methodology of counter-rotating fans for application in roadable electric aircraft ‘Airavat’ and the effect of different loading (total pressure) distributions in front and rear rotor on its overall performance. The fan is required to provide 10 N thrust and hence is designed for total pressure rise of 1000 Pa. The dimension of the fan is decided according to the design constraints of the vehicle. Rotors are designed for the rotational speed of 7500 rpm (Counter-clockwise and clockwise respectively) and flow coefficient of 1.25 at the mid. There are 8 blades in the front and 7 blades in the rear rotor. Fans are designed for four different total pressure rise and hence loading distributions namely, 1) 50%-50%, 2) 55%-45%, 3) 60%-40% and 4) 65%-35% in front and rear rotor. Other design parameters are kept the same for all the four cases.
The performance of the fans with different loading distributions is evaluated through computational study in Ansys CFX using mixing plane approach. It is observed that, as the loading increases in the front rotor, blade camber increases. The blade becomes more prone towards flow separation near the trailing edge under an adverse pressure gradient. Wake coming out from the front rotor grows thicker with higher loading, leading to flow acceleration (thus total pressure loss) in the axial gap between these rotors. As a consequence, flow incidents on the rear rotor other than the design incidence and thus the rear rotor operates under off-design condition. For the equal loading distribution case, the rear rotor does not provide the designed total pressure rise even though the front rotor performs well. With 55%-45% loading distribution, both the rotors give desired total pressure rise and maximum stable operating range. The detailed flow field study is discussed to bring important outcomes for achieving the desired total pressure rise.
Detailed Heat Transfer Characteristics of Matrix Cooling Channels With Rib Angle 35° Using Liquid Crystal Thermography
Authors: Prajapati Anjana N. , Tariq Andallib 
Published: January 2020

Abstract
Matrix cooling is relatively newer cooling technique and preferred over the conventional rib turbulators or pin fin cooling due to its capacity to provide the structural rigidity and higher heat transfer enhancement. The present investigation addresses the detailed study of local and averaged heat transfer augmentation distributions within the sub-channels of matrixes with rib angle 35° and varying sub-channels aspect ratios using liquid crystal thermography. The effects of varying sub-channel aspect ratios 1.2, 0.8 and 0.4 on averaged Nusselt number augmentation, friction factor ratio and thermo-hydraulic performance factor have been also verified within the Reynolds numbers range 5800–14000. The flow trend within the sub-channels is typically found to be eccentric and attributed to the possible vortical flow within the sub-channels and this eccentricity reduces as the sub-channel aspect ratio decreases. Results have shown that the highest Nusselt number augmentation and the lowest friction factor ratio are obtained for the highest sub-channel aspect ratio i.e., the best thermo-hydraulic performance factor (≥ 1) has been found for sub-channel aspect ratio 1.2. The sub-channel aspect ratio is found to have significant effect on both Nusselt number augmentation and friction factor ratio as compared to Reynolds number.
Impact of Sinusoidal Tip Gaps on Axial Compressor Rotor Performance: A Flow Field Investigation
Authors: Goswami Shraman , Malhotra Ashima 
Published: January 2020

Abstract
Performance of an axial compressor rotor depends largely on the tip leakage flow. Tip leakage flow results in tip leakage vortex which is a source of loss. This has an impact on the compressor efficiency as well as stall margin. A lot of work has been done to understand the tip leakage flow and controlling the same. Active and passive stall margin improvement methods mainly target the tip leakage vortex.
In the current study, numerical investigations are carried out to understand flow fields near tip region of rotors. The blade tip designed to have a tip gap as sine and cosine waves (single and double waves). Numerical methodology is validated with NASA Rotor37 test results. The performance parameters of the rotors with modified tip gap shapes are compared with constant tip clearance rotor. A detailed flow field investigation is presented to compare the tip flow structure and its impact on overall performance of the compressor.
Estimation of Active Magnetic Bearings (AMB) Dynamic Parameters and Residual Mass Imbalance Using FEM With PID Controller and Identification Algorithm of a Flexible Rotor System Fully Levitated on AMB
Authors: Murugan S. Bala , Behera R. K. 
Published: January 2020

Abstract
The dynamic analyses of rotating systems are always a testing task to obtain the definite results. This paper carries the dynamic modelling, analysis and identification of coupled flexible rotor system supported by an auxiliary Active Magnetic Bearings (AMBs). An identification algorithm is used to estimate the dynamic parameters of AMB, and rotor residual mass imbalance. The proposed algorithm is a right method for the analysis of fully levitated rotor on AMBs. Finite element method is used to model the dynamic flexible rotor system with PID controller. A conventional dynamic condensation technique is implemented in the development of identification algorithm to overcome the difficulty in numerical simulation. The least-squares fit technique is deployed to estimate the dynamic parameters in frequency domain. Then the algorithm is extended to find the misalignment forces and moments at the coupling point. Numerical study is carried to check the correctness of the algorithm. The proposed algorithm is yet to be tested to experimental results from a fully levitated rotor test rig supported with AMBs.