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Статті в журналах з теми "629.1.04"
1
Awang Saifudin, Awang Raisudin, and Nurul Musfirah Mazlan. "Computational Exploration of a Two-Spool High Bypass Turbofan Engine's Component Deterioration Effects on Engine Performance." Applied Mechanics and Materials 629 (October 2014): 104–8. http://dx.doi.org/10.4028/www.scientific.net/amm.629.104.
Повний текст джерелаАнотація:
Aircraft engines are exposed to degradation due to several factors such as environmental air pollution, fuel content and ageing or degradation of engine’s components, which are experienced within specified time. While the turbofan in operation, its components deteriorate and consequently affect its performance. This study is aimed to computationally investigate the effect of components degradation on engine performance. A high bypass turbofan engine operated at cruise is selected for this evaluation and the simulation was performed using the Gas Turbine Simulation Program (GSP). The affected components considered are turbines and compressors with deterioration rate ranging from 0% to 5%. The effect of selected deterioration rate on engine thrust and thrust specific fuel consumption (TSFC) is studied. Results obtained show an agreement with literature where reduction in engine thrust and TSFC are observed. Turbine’s fouling has been found to be more severe than erosion in terms of power and efficiency losses. However, in terms of the overall performance, the erosion effect is more severe than fouling.
2
LEKVEISHVILI, MARIAM, and HANS KLOMPEN. "Phylogeny of infraorder Sejina (Acari: Mesostigmata)." Zootaxa 629, no. 1 (September 3, 2004): 1. http://dx.doi.org/10.11646/zootaxa.629.1.1.
Повний текст джерелаАнотація:
Phylogenetic relationships among the families in the infraorder Sejina and the position of Sejina relative to other infraorders of Mesostigmata are re-examined based on molecular and morphological data. Data sets included DNA sequence data for complete 18S, EF-1 , partial CO1genes, and 69 morphological characters. The two families of Heterozerconina consistently group within Sejina, and we propose to synonymize Heterozerconina with Sejina (Sejina s.l). Microgyniina is not the closest relative of Sejina. Rather, Sejina s.l. most often groups with Gamasina. Uropodellidae and Ichthyostomatogasteridae are sister groups and this lineage forms the sister group to Discozerconidae plus Heterozerconidae. Overall, we recognize 5 families within Sejina: Uropodellidae, Ichthyostomatogasteridae, Sejidae, Discozerconidae, and Heterozerconidae.
3
He, Yi Qiang, Bin Qiao, Jian Ming Yang, and Li Chao Feng. "Research Status and Developing of Metal Injection Molding." Advanced Materials Research 629 (December 2012): 100–104. http://dx.doi.org/10.4028/www.scientific.net/amr.629.100.
Повний текст джерелаАнотація:
Metal injection molding(MIM) is a high efficient and near net shape manufacturing technology, which is appropriate for parts of small size and complex shape. MIM provides a viable method to fabricate metal and metal matrix composites with discontinuous reinforcements, and micro metal injection molding (μMIM) is applied to manufacturing products at micro scale. The status of the research and development of MIM and μMIM are reviewed. Processes including mixing, injection molding and subsequent debinding and sintering are summarized. And technical characteristic, injection processing and application of μMIM are introduced. The disadvantages in mixing, injection molding and debinding processes limit MIM to fabricating components with small size, low precision and mechanical properties, and it is necessary to prevent the powder from reuniting and avoid any oxidation and impurity during μMIM process. Further investigations in these areas will give rise to being explored of full potential of MIM technology.
4
He, Yi Qiang, Jian Ming Yang, Bin Qiao, and Li Chao Feng. "Microstructure and Mechanical Properties of Metal Injection Molded SiCP/ Cu Composites." Advanced Materials Research 629 (December 2012): 105–9. http://dx.doi.org/10.4028/www.scientific.net/amr.629.105.
Повний текст джерелаАнотація:
SiCP/Cu composite was prepared by metal injection molding process. Microstructure, mechanical properties, fracture surface, and wear resistance of SiCP/Cu composite were investigated in this study. The research results show that SiCP/Cu were sintered sucessfully by the sintering process with hydrogen protection and high temperature of 1050°C. The tensile strength of the composites depends on the fraction and distribution of SiC particles which is resulted from microcracks nucleate in the matrix between SiC particles because of SiC particle aggregation. The tensile strengths of 5vol.%, 10vol.%, and15vol.%SiCP/Cu are 254MPa, 291MPa and 278MPa separately. SiC particles are contribute to enhance the abrasive resitance of the composite when particle volume fraction increase from 10% to 15%.
5
Li, Wei Dong, Gang Liu, Xue Feng An, and Xiao Su Yi. "Effects of Z-Direction Flowing RTM Technology on Distribution of Composites Fiber Volume Fraction and Thermoplastic Toughener." Advanced Materials Research 629 (December 2012): 110–14. http://dx.doi.org/10.4028/www.scientific.net/amr.629.110.
Повний текст джерелаАнотація:
In this paper, a novel Z-direction flowing RTM technology using an in-mold resin distributor has been applied to the “Ex-situ” composites and the process feasibility was evaluated. The effect of injection type on distribution of fiber volume fraction and thermoplastic toughener in the composite were investigated. The results showed that perfect internal quality composite panels could be fabricated via the novel RTM technology and the injection type has some effects on distribution of fiber volume fraction along the thickness direction of the panels. After the injection and curing cycle, the typical bicontinuous phase structures were mainly observed at the interlaminar and also slightly spreading into the fibre beam.
6
Ma, Qiang, and Jun Zhi Cui. "Second-Order Two-Scale Analysis Method for the Quasi-Periodic Structure of Composite Materials under Condition of Coupled Thermo-Elasticity." Advanced Materials Research 629 (December 2012): 160–64. http://dx.doi.org/10.4028/www.scientific.net/amr.629.160.
Повний текст джерелаАнотація:
The second-order two-scale asymptotic expansions of the increment of temperature and the displacement for the quasi-periodic structure of composite materials under coupled thermo-elasticity condition are derived formally in this paper. The characteristic of the asymptotic model is the coupling between macroscopic scale and microscopic scale. Numerical examples including different coefficients are presented illustrating the efficiency and stability of the computational strategy. They show that the expansions to the second terms are necessary to obtain the thermal and mechanical behavior precisely, and the local and global oscillation of the increment of temperature and displacement are dependent on the microscopic and macroscopic part of the coefficients respectively.
7
Shen, Xian Feng, Wen Hua Teng, Wen Rong Huang, and Chao Xu. "Gas-Jet-Assisted Keyhole Laser Welding of Q235 Mild Steel." Advanced Materials Research 629 (December 2012): 180–86. http://dx.doi.org/10.4028/www.scientific.net/amr.629.180.
Повний текст джерелаАнотація:
Increases in the penetration depth of laser welding has gained undoubted interest, especially in the aerospace, power station, ship building, and other heavy industries. Gas-jet-assisted keyhole laser welding is a prospective method for improving the penetration of conventional laser welding. A series of experiments using this method were conducted with different parameters of the assisted gas jet and the welding speed. The microstructures of weld joints were observed using optical microscopy, and microhardness was also measured. The investigation results showed that the penetration depth of this laser welding increased by more than 20%, with a maximum increase of approximately 26%, at different welding speeds, while the weld width was significantly reduced compared with that of conventional laser welding. The key factor affecting the penetration increase is the interaction between the assisted gas jet and the plasma. The penetration increase was determined by the distribution and amplitude of the assisted gas jet at the position of the keyhole orifice. The grain in the heat-affected zone (HAZ) and weld seam of gas-jet-assisted keyhole laser welding was finer, and the number of columnar grains was also significantly reduced. The microhardness of the HAZ for the assisted gas jet was much lower, and more pearlite and less martensite were observed this zone. This was caused by the reduced maximum temperature of the molten pool, reduced high-temperature residence time, increased cooling rate, and diminished temperature gradient with the introduction of the assisted gas jet.
8
Xiang, Jun Ting, Jӧrg Uwe Schlüter, and Fei Duan. "CFD Validation and Analysis of a Single-Stage Axial Compressor." Applied Mechanics and Materials 629 (October 2014): 109–18. http://dx.doi.org/10.4028/www.scientific.net/amm.629.109.
Повний текст джерелаАнотація:
The knowledge about changes of flow field properties during axial compressor operationat high and relatively low speed is limited. This work provides a numerical approach to addressthese problems. Validations about the numerical scheme and the test of compressor performance at various operating speeds are conducted. The results show that computational fluid dynamics (CFD)is capable in predicting the compressor performance. Flow property changes during the compressoroperation are discussed and explanations are proposed. This work reinforces the understanding of compressor operation and provides valid results for future reference.
9
Burston, Martin T., Roberto Sabatini, Reece Clothier, Alessandro Gardi, and Subramanian Ramasamy. "Reverse Engineering of a Fixed Wing Unmanned Aircraft 6-DoF Model for Navigation and Guidance Applications." Applied Mechanics and Materials 629 (October 2014): 164–69. http://dx.doi.org/10.4028/www.scientific.net/amm.629.164.
Повний текст джерелаАнотація:
A method for deriving the parameters of a six-degree-of-freedom (6-DoF) aircraft dynamics model by adopting reverse engineering techniques is presented. The novelty of the paper is the adaption of the 6-DoF Aircraft Dynamics Model (ADM) as a virtual sensor integrated in a low-cost navigation and guidance system designed for small Unmanned Aircraft (UA). The mass and aerodynamic properties of the JAVELIN UA are determined with the aid of an accurate 3D scanning and CAD processing. For qualitatively assessing the calculated ADM, a trajectory with high dynamics is simulated for the JAVELIN UA and compared with that of a published 6-DoF model of the AEROSONDE UA. Additionally, to confirm the validity of the approach, reverse engineering procedures are applied to a published CAD model of the AEROSONDE UA aiding to the calculation of the associated 6-DoF model parameters. A spiral descent trajectory is generated using both the published and calculated parameters of the AEROSONDE UA and a comparative analysis is performed that validates the methodology. The accurate knowledge of the ADM is then utilized in the development of a virtual sensor to augment the UA navigation and guidance system in case of primary navigation sensor outages.
10
Jo, Hudyjaya Siswoyo, Mark Tee Kit Tsun, and Carmella Sim Lee Yoong. "Development of Blimp Platform for Aerial Photography." Applied Mechanics and Materials 629 (October 2014): 170–75. http://dx.doi.org/10.4028/www.scientific.net/amm.629.170.
Повний текст джерелаАнотація:
This paper presents the development of a semi-automated blimp platform for aerial photography. The blimp can be tele-operated from a ground station and is capable of autonomously holding its heading and altitude when the pilot releases control. The blimp consists of a helium-filled envelope to achieve the buoyancy and a pair of propellers to drive the blimp in the desired direction. A basic control algorithm and sensing system are also proposed to control and maintain the heading and altitude of the blimp.
Дисертації з теми "629.1.04"
1
Левченко, Віталій Михайлович. "Пристрій активної безпеки автомобіля". Master's thesis, Київ, 2018. https://ela.kpi.ua/handle/123456789/25876.
Повний текст джерелаАнотація:
Метою магістерської дисертації є покращення параметрів та характеристик активної безпеки автомобіля та розширення її застосування. Задачами дослідження є: аналітичний огляд існуючих систем безпеки автомобіля; розробка пристрою автомобільної безпеки та виконання його моделювання; дослідження та аналіз характеристик спроектованого пристрою.
– об’єкт дослідження — пристрій для зменшення вірогідності дорожньо-транспортної пригоди та забезпечення безпеки пасажирам автомобіля.
– предмет дослідження — параметри та характеристики пристрою та систем активної безпеки автомобіля на його основі.
– методи дослідження: теоретичний розрахунок та експериментальне дослідження параметрів макету пристрою.
– наукова новизна одержаних результатів: запропоновано та досліджено використання пристрою автомобільної безпеки з представленим алгоритмом роботи.
– апробація результатів дисертації. міжнародна наукова інтернет–конференція «Інформаційне суспільство: технологічні, економічні та технічні аспекти становлення» (Випуск 32, 16 жовтня 2018р).The purpose of the master's thesis is to improve the parameters and characteristics of active safety of the car and extend its application. The objectives of the study are: an analytical review of existing car security systems; development of the automobile safety device and its simulation; research and analysis of characteristics of the designed device. the object of research - a device for reducing the probability of road traffic accidents and ensuring the safety of passengers of the car. subject of research - parameters and characteristics of the device and active safety systems of the car on its basis. research methods: theoretical calculation and experimental study of parameters of the device layout. scientific novelty of the obtained results: the use of the device of automobile safety with the presented algorithm of work is offered and researched. approbation of the results of the dissertation. International Scientific Internet Conference "Information Society: Technological, Economic and Technical Aspects of Formation" (Issue 32, October 16, 2018).
2
Verdin, Patrick. "An automatic multi-stepping approach to aircraft ice prediction." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/2923.
Повний текст джерелаАнотація:
Flying an aircraft in icing conditions may seriously degrade its aerodynamical performance
and threaten the flight safety. Over the years, new technologies and improved
procedures have limited the potential risks caused by aircraft icing. Experimental
studies being very expensive, numerous computer codes have been developed to
simulate ice shapes and tackle the problem. Typically in these codes, a flow solution
and key icing parameters are evaluated around a clean un-iced geometry and
their values remain constant during the entire simulation. This approach may be
acceptable for short exposure times or when the ice shape only slightly deforms the
initial geometry. However, in other cases, the values of the icing parameters may
vary and the simulation will loose its accuracy: for large shapes, the presence of
the ice influences the surrounding airflow significantly, altering the value of icing
parameters and ultimately the ice accretion. Calculating more accurate ice shapes
therefore requires to periodically recompute the flow field around the body during
the simulation and determine updated values for icing parameters. This procedure,
known as multi-stepping, is investigated in this thesis and adapted to the new threedimensional
icing code ICECREMO2. Several multi-step algorithms are presented
and tested on cylinders and airfoils. When possible, the ice shapes simulated are
compared with experimental results.
The first multi-step calculations were generally performed manually. The user
had to perform a rather tedious work and inappropriate instructions could lead to
severe inaccuracies in the simulations. To avoid these difficulties, a fully automated
procedure will be developed including all stages of a multi-step computation. This
significantly reduces user interaction and the overall computing time.
The present research work forms part of the ICECREMO2 project. ICECREMO2
is a three-dimensional ice accretion and water flow code developed collaboratively
by Airbus UK, BAe Systems, Dunlop Aerospace, Rolls-Royce, GKN Westland Helicopters,
QinetiQ and Cranfield University under the auspices of the UK Department
of Trade and Industry.
i
3
Quero, García Manuel. "Analytical and experimental investigation into the thermal aspects of droplet impingement." Thesis, Cranfield University, 2006. http://hdl.handle.net/1826/4043.
Повний текст джерелаАнотація:
The mechanics and heat transfer of droplet impact is studied in the range of
parameters interest for Super-cooled Large Droplet icing. The investigation explores
the development of the splash produced experimental and numerically.
A Navier-Stokes solver has been developed in order to compare experiments and
modelling.
Heat transfer is included in the simulations making possible the analysis of the
thermal history during the impact of a Super-cooled droplet into a warm and running
thin water film.
Also a theoretical and numerical study has been undertaken in order to simulate
the first stages of ice formation on the critical surfaces of aircraft during the droplet
impact under freezing conditions due to super-cooled icing.
The parameters considered experimental and numerically are:
• Droplet size: 100-700Jlm.
• Droplet impact velocity: 18-80m/s.
• Angles of impact: 70°,45° and 20°.
• Airflow (droplet) temperature: 200 e and _lOoe.
• Water film thicknesses: 150Jlm and 50Jlm.
• Water film temperature: 15°e and lOoe.
• Water film velocity: 5m/s.
The simulations are compared to the experiments run under the same conditions.
Results for the parameters at the early stages of the splash agree well but as the splash
process continues there are more differences between the two sets of results.
4
Butters, Jonathan David. "Terminology recognition in the aerospace domain." Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.575750.
Повний текст джерелаАнотація:
The objects and phenomena within the world around us are frequently shared. Common understandings, intuition, and common sense allow people to communicate ideas and instructions by identifying the semantics of the words used. When we communicate these ideas through text, we rely on strings of characters to carry semantics, and through these, because of common understandings, intuition, and common sense we are often able to gain back the references to the original ideas. As people's capacity to express their ideas through text is unbounded, the task of deciphering original meanings when synonyms and term variations are involved can be challenging, trying to do this task automatically is more so. The body of work within this thesis aims to identify and then overcome the challenges in automatically recognising the terminology used for concepts within the aerospace domain. The main achievements of this thesis include new knowledge about the use of terminology in this safety critical and highly technical domain, knowledge that approaches which are often impractical in open and alternate domains may be applicable due to the aerospace domain's unique nature, and an approach to automatically recognising terminology for the purposes of knowledge management. The approach involves constructing an explicit model of the domain (afforded by its closed nature), and then leveraging it along with exploiting the combinatorial nature of aerospace domain terms in an extraction methodology. Extraction is performed using a novel, hybrid dictionary and machine learning based technique which is shown to perform better than existing dictionary, statistics, and machine learning techniques. This thesis is organised into four parts, the first part provides a survey of the aerospace domain and state of the art methods by which terminology is recognised. The second part documents several investigations into the real-world use of terminology within and across aerospace-based communities in order to provide an understanding on how terminology should be recognised and generate a set of requirements. The third part details the proposed approach and presents a novel, patent-pending methodology to fulfil the requirements. The fourth part concludes this thesis with a summary and by v answering the original research questions, before discussing possible lines of future work.
5
Lajux, Vincent. "Methodology for the design of leading edge devices applied to variable camber." Thesis, Cranfield University, 2007. http://hdl.handle.net/1826/2548.
Повний текст джерелаАнотація:
This thesis will describe a new and innovative way of approaching the design of leading
edge devices; this done using new tools and state of the art software. This innovative
design methodology for leading edge devices has a special focus on the application of
variable camber technology.
A precise description is given of the way to check that methodology acts as a means of
validation.
A case study shows how to apply this methodology and examines a variable camber
application. This case study provides the basis for the understanding of how to apply the
design methodology and give results generated from its different parts. An analysis of the
structure and aerodynamic performances of a new type of leading edge device was
performed in addition to moving the overall design towards an optimum solution in term
of mass, reliability and cost.
The case study is showing that using a variable camber leading edge device could be
beneficial as it proves a better option than more classical concepts. Some of the results
show that the aerodynamics implications of using this type of device at the leading edge
can be beneficial in cruise and also during take off and landing. Also on the structural
side of things, it is possible to see that the deployment trajectory as been optimised to fit
to the required trajectory and the structure is able to resist critical loading.
Finally there is a discussion on the obtained results and on the overall methodology to
make conclusions on the overall meaning of this research and the possible impact of the
new design methodology as well as implication on the design of variable camber leading
edge devices.
6
Laskaridis, Panagiotis. "Performance investigations and systems architectures for the More Electric Aircraft." Thesis, Cranfield University, 2004. http://hdl.handle.net/1826/2958.
Повний текст джерелаАнотація:
Implementation of all or more electric technologies has the potential of improving the performance of a given aircraft. Savings can manifest through improved engine performance, reduced equipment weight and improved secondary power and systems utilization. Despite the potential benefits and the amount of research invested the concept has not been implemented yet and its impact on the overall performance of the aircraft remains unclear. Adoption of a single form of secondary power and implementation of more or all electric technologies is claimed to offer a number of distinct advantages over the conventional secondary power systems. These claims include the following: 1. Improved engine performance through the optimization of off-takes and elimination of bleed air. These issues is said to become critical as the bypass ratio of the engine increases and the size of the core reduces. However, despite concerns over the capability of high bypass ratio to provide secondary power requirements of future aircraft the claims remain unproven and it is generally believed that off-take penalties are not dependent on the configuration of the engine and can be kept to a minimum if the engine is designed to provide them. 2. Improved system utilization and implementation of more efficient power units. Conventional secondary power systems developed during the years that fuel was relatively fuel was relatively inexpensive and have not been optimized for maximum efficiency. Bleeding air from the engine is largely inefficient and a large amount of power is wasted for no useful purpose. In addition, hydraulics are often sized for loads that are small in duration thus increasing the mass and power requirements of the system. Elimination of conventional hydraulic and bleed air systems could lead to a significant mass reduction. However, the mass and size of the electrical equipment would also increase and these changes must be accounted for. 4. Additional benefits include reduced single type maintenance, improved reliability and life cycle costs. The present study is focused on assessing the potential benefits of adopting the all or more electric aircraft concepts in the case of high capacity long-range aircraft. Previous studies concentrated on low to medium range aircraft powered by medium bypass bass ratio engines. As a result, the moderate power requirements and the more important weight considerations, for the class of aircraft reviewed, reduced the potential benefits and led to retrofitted designs with low savings. It is thought that high capacity long range aircraft as those examined by the present study are more suited to the all electric concepts and could benefit more. The study was aimed to address the first three claims made and also provide a better understanding of the issues involved. As a result the following topics have been considered. The effects of off-takes on the performance of the engine were studied. Two methods for assessing these effects were developed. The analysis concluded that engine parameters such as pressure ratio and turbine entry temperature have an important effect on the performance of an engine operating with bleed air or shaft power extraction.
An aircraft performance model was developed and used to asses the impact of all or more electric technologies on aircraft in the classes of A330-200, A340-500 and A380-100. The models were validated against published payload range data. All electric derivatives were developed by incorporating changes in aircraft mass and engine off-takes. Sensitivity studies were also conducted. Conceptual designs and electric system architectures were developed and studied. Adoption of all electric technologies and elimination of the hydraulic system was estimated to reduce the OEW by 0.4% to 0.1% for the A330-200 class aircraft, 0.37% to 0.25% for the A340-500 class aircraft and 0.3% to 0.1% for the A380-100 class aircraft. The total fuel reduction with implementation of all electric technologies and elimination of hydraulics and bleed air could be as high as 2.6% for the A330-200 class aircraft, 2.75% for the A340-500 class aircraft and 3.5% for the A380-100 class aircraft. Adoption of all or more electric technologies could allow for the design of more efficient aircraft. Increasing the aspect ratio of the A80-100 class aircraft to 8.33 could improve aerodynamic efficiency leading to an overall fuel reduction of 4.4% and a MTOM reduction of 2.0010. In the case of twin engine aircraft reductions in MTOM and reduced off-take penalties could allow an increase in engine bypass ratio leading to increased overall performance. For the A330-200 class aircraft elimination of bleed air and increase in bypass ratio resulted in a fuel reduction of 4.5%.
7
Padulo, Mattia. "Computational engineering design under uncertainty : an aircraft conceptual design perspective." Thesis, Cranfield University, 2009. http://hdl.handle.net/1826/4462.
Повний текст джерелаАнотація:
Presented in this thesis is a novel methodology for aircraft design optimization in the presence of uncertainty, with emphasis on the conceptual design stage.
In the initial part of the thesis, the uncertainty typologies of interest for aircraft design are identied within a broader epistemological framework. The main implications for non-deterministic computational design are also outlined.
The focus is then restricted to uncertainties that can be modeled by probability theory. In this context, a methodology is developed to enhance robust design optimization (RDO). Firstly, the problem is formulated in order to relax, when required, the common RDO assumption about the normality of objectives and constraints. Secondly, starting from engineering considerations about the risk related with design unfeasibility, suitable estimates of tail conditional expectation are introduced in the set of robustness metrics.
The proposed formulation requires the estimation of mean and variance of objec¬tives and constraints. To calculate such moments, a novel uncertainty propaga¬tion technique is proposed, which achieves a favorable trade-obetween the ac-curacy of the estimates and the required computational cost. Peculiar features of the propagation technique are exploited to couple the propagation and the opti¬mization phases for the classes of gradient-based methods and the derivative-free pattern search methods. Also analyzed are the possible advantages achievable when the two types of algorithms are hybridized.
The usefulness of the proposed methodology for conceptual design optimization is demonstrated with the aid of two engineering design problems, concerning the sizing of passenger aircraft and the design of transonic airfoils.
8
Gullia, Alessandro. "Thrust and Flow Prediction in Gas Turbine Engine Indoor Sea-Level Test Cell Facilities." Thesis, Cranfield University, 2006. http://dspace.lib.cranfield.ac.uk/handle/1826/7496.
Повний текст джерелаАнотація:
The principal aim of this research was to provide a detailed understanding of the
performance of gas turbine engines inside indoor sea-level test beds. In particular the
evaluation of both thrust correction factors and the estimation of the mass flow
entering the test cell were at the core of the research.
The project has been fully sponsored by Rolls-Royce pIc. Initially, their principal
objective was to assess the relevance and accuracy of CFD when applied to thrust
measurement inside indoor test beds with an intended outcome of minimising the use
of expensive experimental measurements.
The different system interfaces and accounting systems for in-flight conditions,
available in the open literature have been developed and adapted for indoor
environments. This has led to the definition of three different thrust correction
equations using alternative definitions of thrust correction factor. Aero-dynamic
principles have been applied for the derivation of one-dimensional relationships for
the calculation of each thrust correction factor using generic engine-cell performance
and dimensions.
A one-dimensional analytical model has been developed to represent the enginedetuner
ejector pump. This is able to characterise the engine-cell system performance
and is used as the main tool for providing a matching procedure capable of predicting
the cell entrainment ratio.
By processing experimental data relevant to different engine-cell configurations
through the ejector pump analytical model, a method for achieving the entrainment
ratio control inside the cell has been identified.
The CFD work has been concentrated into three main activities:
• A quantitative extrapolation of the thrust correction factors including, the
pre-entry force, the external and the total bellmouth force, the throat stream
force, the intake momentum drag and the base drag.
• The representation of the engine-detuner ejector performance for a
variety of engine-cell configurations.
• The modelling of the generic test cell components including the inlet
stack, the cascade elbow, the exhaust stack & the blast basket.
The outcomes of this research have been very successful in enhancing the validity of
the thrust correction equations developed .. In particular, the use of a one-dimensional
approach in their estimation has been shown to be fully justified. The work has also
emphasised the value of CFD in supporting the derivation of the matching procedure
for predicting and controlling cell entrainment ratio. Indeed, one of the strongest
outcomes of this work has been the conclusion that both the engine-cell characteristic
lines computed with the one-dimensional model and those computed with CFD for
different cell configurations are almost identical.
In addition, the use of CFD as a tool for the quantitative evaluation of the thrust
correction factors has been established. Finally, the CFD results have facilitated an
enhanced understanding of the complex flow structure inside indoor test cells
9
Janikovic, Jan. "Gas turbine transient performance modeling for engine flight path cycle analysis." Thesis, Cranfield University, 2010. http://dspace.lib.cranfield.ac.uk/handle/1826/7894.
Повний текст джерелаАнотація:
The growth in competitiveness in airline industry has called for more advanced tool to
estimate the operating costs. Engine maintenance costs are an important decisionmaking
element during airline fleet selection judgment. Long term observation in
aerospace led to the development of engine maintenance costs calculators based on
empirical correlation. But the possibilities of empirical model application for future
engines without prior operational data are limited.
A physics-based tool to estimate the life of the engine components and predict the
shop visit rate requires the variations of thermodynamic parameters over the flight
path. High fidelity engine models are simulated using an engine performance program.
A test program designated for design, off-design and transient performance simulation
for simple turbojet layout gas turbine engine has been programmed and tested. The
knowledge gained from program coding was used to generate more robust transient
performance code implemented to Turbomatch. Two transient methods have been
tested: The rapid transient performance method and the thermodynamic matching
method. The tests showed greater robustness and stability of the second method,
which has been finally adopted for the program. For industrial engine configuration
and for future novel engine cycles the heat-exchanger dynamic response model was
implemented and tested.
Created tool was demonstrated on short-haul study of engine flight path analysis.
Together with the aircraft model, the tool produced variations of parameters needed
for the lifing algorithm.
10
Giannakakis, Panagiotis. "Design space exploration and performance modelling of advanced turbofan and open-rotor engines." Thesis, Cranfield University, 2013. http://dspace.lib.cranfield.ac.uk/handle/1826/7957.
Повний текст джерелаАнотація:
This work focuses on the current civil engine design practice of increasing overall pressure
ratio, turbine entry temperature and bypass ratio, and on the technologies required in
order to sustain it. In this context, this thesis contributes towards clarifying the following
gray aspects of future civil engine development:
the connection between an aircraft application, the engine thermodynamic cycle and
the advanced technologies of variable area fan nozzle and fan drive gearbox.
the connection between the engine thermodynamic cycle and the fuel consumption
penalties of extracting bleed or power in order to satisfy the aircraft needs.
the scaling of propeller maps in order to enable extensive open-rotor studies similar
to the ones carried out for turbofan engines.
The rst two objectives are tackled by implementing a preliminary design framework,
which comprises models that calculate the engine uninstalled performance, dimensions,
weight, drag and installed performance. The framework produces designs that are in
good agreement with current and near future civil engines. The need for a variable area
fan nozzle is related to the fan surge margin at take-o , while the transition to a geared
architecture is identi ed by tracking the variation of the low pressure turbine number of
stages. The results show that the above enabling technologies will be prioritised for long
range engines, due to their higher overall pressure ratio, higher bypass ratio and lower
speci c thrust. The analysis also shows that future lower speci c thrust engines will su er
from higher secondary power extraction penalties.
A propeller modelling and optimisation method is created in order to accomplish the
open-rotor aspect of this work. The propeller model follows the lifting-line approach and
is found to perform well against experimental data available for the SR3 prop-fan. The
model is used in order to predict the performance of propellers with the same distribution
of airfoils and sweep, but with di erent design point power coe cient and advance ratio.
The results demonstrate that all the investigated propellers can be modelled by a common
map, which separately determines the ideal and viscous losses.
Частини книг з теми "629.1.04"
1
"International Criminal Law, Humanitarian Law and the Responsibility of States for Choice of Forum and Effective Enforcement." In The Challenge of Conflict: International Law Responds, 299–314. Brill | Nijhoff, 2006. http://dx.doi.org/10.1163/ej.9789004145993.i-629.103.
Повний текст джерела
2
"Challenges for the International Criminal Court: Terrorism, Immunity Agreements and National Trials by." In The Challenge of Conflict: International Law Responds, 315–30. Brill | Nijhoff, 2006. http://dx.doi.org/10.1163/ej.9789004145993.i-629.106.
Повний текст джерела
3
"Could Systematic Sexual Violence against Women During War Time Have Been Prevented? Lessons from the Japanese Case of Comfort Women." In The Challenge of Conflict: International Law Responds, 499–513. Brill | Nijhoff, 2006. http://dx.doi.org/10.1163/ej.9789004145993.i-629.174.
Повний текст джерела