1,721,194 research outputs found
Mechatronics numerical modelling for integrated turbo-electric techno-economic environmental risk assessment
No full textPilidis, Pericles - Associate SupervisorLong-term targets from the aerospace administration are to have cleaner, cost-efficient, and more performance-efficient transportation. The National Aeronautics and Space Administration (NASA) has proposed several solutions to hybrid technology, of which the turbo-electric distributed propulsion (TeDP) model is one of the latest promising models. This research project presents numerical modelling of the integrated TeDP model through the method of assisting technical performance, considering the economic and environmental risks. The contribution to numerical modelling is an integrated electrical module on the academic multidisciplinary Cranfield University gas-turbine TurboMatch® simulation tool with the projected method. In piloting this project, the outcome of this work advances the knowledge of TeDP and the future technology of aviation-distributed propulsion.
Moreover, a proper simulation tool to assist TeDP and ‘more electric aviation’ has been upgraded in TurboMatch. In addition, an integrated development environment (IDE) extension for TurboMatch was developed to investigate the electrical grid in TeDP. This work presents a toolkit for assessing the power and efficiency profiles of the electrical network specified for TeDP. From the given level of thrust, the methodology was used to evaluate and optimise the electrical network. A number of integration electric propulsion models were developed to demonstrate the assisting method for redundancy and reliability improvement. The total goal was to initialise the features of the TeDP mechatronics and electrical grid with the best technical, economic, and environmental solutions for the greatest efficiency.
The implication of this research is to understand the concept of TeDP using the use-case study of NASA’s N3-X conceptual proposal for project progress validation. The contribution knowledge lies in the area of the numeric model and the method to assist TeDP using the devised techno-economic environmental risk assessment (TERA) concept. The project inputs focus on future long-term goals for intelligent TeDP.PhD in Aerospac
Green hydrogen revolution in aviation: requirements and possibilities
Full text linkPilidis, Pericles - Associate SupervisorThis work investigates the case for sustainable aviation for the Asia Pacific region
and focusses on Hong Kong. Hong Kong presently generates 50% of its energy
from coal. The aim is to remove carbon from aviation fuels for Hong Kong and
replace it with green hydrogen. This is a viable choice of sustainable aviation fuel
but switching it from kerosene would require the overcoming of some challenges.
This thesis comprises of three parts: firstly, the modelling and simulation of the
Trent-XWB-97 jet engine as a baseline combusting Jet-A fuel. Its aircraft
performance is then compared to a cryogenically fuelled green hydrogen engine.
Secondly, the reference engine is then fitted with an intercooler with the gain of
aircraft performance benefits in mind as well as to utilise it as a heat exchanger
to vapourise the liquid hydrogen and thirdly, large-scale green hydrogen
production using renewables is envisaged as part of a Green Hydrogen Hub
network encompassing a green hydrogen logistical supply chain paving the way
for a future aviation hydrogen micro-economy. It was discovered that relative to
the Jet-A fuelled engine, the engine with a constant net thrust for ODP (Take-Off)
and DP (Cruise) conditions decreased the ESFC for both baseline and
intercooled engines. For the reference case at ODP this drop in ESFC was
(1.71%) and (1.3%) for the intercooled scenario. There was also an
accompanying decrease in TET; for the baseline engine this was 47K and for the
intercooled engine this was 50K. The addition of the intercooler achieved the
greater aircraft thrust requirement of 448kN and also vapourised the cryogenic
hydrogen to high enough temperatures. These were calculated to be 536K and
296K for the ODP and DP respectively. The results showed that the baseline
engine carried the greatest payload of 31866 kg with a block fuel burn of 36267
kg and a flight duration of 11.83 hours. The intercooled engine yielded a
maximum carried payload of 27184 kg and the block fuel burn was 43349 kg and
a flight time of 11.97 hours. The study also discovered that the 43.4 tonnes of
green hydrogen can be generated in Hong Kong using wind and solar power and
that its usage reduced the civil aviation carbon footprint of Hong Kong by 11.6%.MSc by Research in Aerospac
The impact of heat transfer effects on civil aircraft engine transient performance
No full textPilidis, Pericles - Associate SupervisorDuring gas turbine transient manoeuvre, heat transfer occurs between the fluid
and metal. This results in various heat transfer effects, including heat soakage,
tip clearance, and change in component performance map. These will cause heat
loss and change in component flow characteristic and efficiency, which further
affect gas turbine transient performance. In this work, a comprehensive heat
transfer model including heat soakage, tip clearance and compressor map
modification has been developed. The proposed heat soakage model improves
the current state-of-the-art model by establishing a comprehensive thermal
network with the consideration of the combustor temperature distribution and
cooling technologies including film cooling, internal cooling, and thermal barrier
coatings. Additionally, the proposed novel compressor map modification model
can derive numerical correlations for compressor maps based on movement of
compressor speed line and map scaling, enabling the modification of adiabatic
maps to non-adiabatic maps during transient simulations. It improves the current
compressor map modification models by ensuring both flexibility and accuracy.
The developed heat transfer model has been integrated into Cranfield gas turbine
simulation platform Turbomatch, enhancing the realism of transient simulations.
The accuracy of the proposed model has been validated against data from public
sources, simulation platforms, and experimental results. A sensitivity analysis has
also been conducted to assess the impact of various assumptions on heat flow
rate estimation. The impact of heat transfer to overall engine’s performance has
been demonstrated by simulating transient operation of a turbojet and two
turbofan engines to demonstrate the effects of heat transfer on gas turbine
transient performance. Comparing with the conventional heat soakage method,
the application of the improved models can capture a delay on engine’s response
beyond the one simulated by the existing methods. This is a result of considering
the combustor temperature distribution and cooling technologies, not included in
the conventional heat soakage models. For the impact of heat transfer effect on
compressor characteristic and performance, a 4% reduction in compressor surge
margin is observed during a hot reslam transient manoeuvre, as a result of
movement in compressor speed line due to heat transfer effect.PhD in Aerospac
Legibility of machine readable codes used for gas turbine part tracking
Full text linkGas turbines are comprised of many parts, which are often expensive and required to
survive a harsh environment for significant periods (with or without reconditioning). To
differentiate between parts, and facilitate keeping accurate historical records, they are
often given a unique identification number. However, manually recording and tracking
these is difficult. This has led to increased adoption of machine readable codes to help
reduce or eliminate many of the issues currently faced (mostly human error). The harsh
environment of a gas turbine means that typical methods of applying machine readable
codes, such as printed adhesive labels, are simply not durable enough. Direct part marking
(DPM) is necessary to ensure the desired longevity of the code over the part's useful life.
The research presented in this thesis was approached in two main phases. Firstly, the
author sought to investigate the technical solutions available for the elements required
of a part tracking system (encoding, marking and scanning). This included identifying
the characteristics of each and their compatibility with one other (across elements). In
conjunction with Alstom, criteria were identified that were used as a basis for comparison
so that the preferred technical solutions could be determined. The outcome of this process
was enhanced by the author developing a number of industrial contacts experienced in
implementing part tracking systems.
The second phase related to the legibility of the codes. The harsh environment of a
gas turbine results in surface degradation that may in turn reduce the legibility of any
machine readable codes present. To better understand why read failures occur, the author
_rst looked to the scanning process. Data Matrix symbols (marked via dot peen) require
the scanner to capture an image for processing. Image capture is typically achieved using
a charge-coupled device (CCD), each pixel of which induces a charge proportional to the
incident illumination. This illumination is received via reflection from the surface of the
part and hence the Data Matrix marked on it. Several surface features were identified that
govern the way in which the part surface will reflect light back to the scanner: surface
roughness, dot geometry and surface colour. These parameters are important because
they link the degradation mechanisms occurring { broadly categorised as deposition,
erosion or corrosion { with the scanning process. Whilst the degradation mechanisms
are distinctly different in their behaviour, their effect on surface reflectivity is common
in that they can all be characterised via the surface parameters identified. This was
deduced theoretically and so the author completed tests (utilising shot blasting to change
the surface roughness and oxidation to change its colour, independently) to show that
these surface parameters do indeed change with the introduction of surface degradation
and that there is a commensurate change in symbol legibility.
Based on the learning derived with respect to Data Matrix legibility, the author has
proposed a framework for developing a tool referred to as a Risk Matrix System. This
tool is intended to enhance the application of part tracking to gas turbine engines by
enabling symbol durability to be assessed based on the expected operating conditions.
The research presented is the first step in fully understanding the issues that affect the
legibility of symbols applied to gas turbine parts. The author's main contribution to
learning has been the identification of knowledge from various other sources applicable to
this situation and to present it in a coherent and complete manner. From this foundation,
others will be able to pursue relevant issues further; the author has made a number of
recommendations to this effect
Poly-dimensional gas turbine system modelling and simulation
No full textThe intense global competition in the commercial aviation and power
generation industry is placing a significant pressure on minimizing cost while
meeting challenging goals in-terms of performance, efficiency, emissions and
reliability. During recent years an opportunity has been identified and is
currently being focused on, for reducing the design and development cost by
largely replacing the larger scale and expensive hardware based testing, with
multi-fidelity and cross-domain predictive simulation platforms. A greater use
of such predictive simulations not only save some costs directly associated
with hardware design and testing but also enables engine design trade-offs
and component interactions, to be studied in detail earlier on before a
commitment is made towards the final hardware design. Experts have
estimated a reduction of 30 to 40% in development time and cost when such
dynamic simulation techniques are implemented. Furthermore, to keep the
engine development on going, joining forces with various gas turbine industrial
manufacturers, research centres and universities especially within the
European Union is of utmost importance because tomorrow's advanced
engine configurations can no longer be developed with today's simulation
tools in the way they are currently used.
The research work, presented within this thesis has been conducted under the
flagship of "VIVACE-ECP" (Value Improvement through a Virtual Aeronautical
Collaborative Enterprise - European Cycle Program) an European Union
sponsored collaborative research project, geared towards the development of
an advanced gas turbine performance modeling and simulation platform with
cross domain analysis capability. The research work undertaken by the author
within the scope of this thesis and the project, fundamentally encompasses
around the two distinct aspects; 1) development of a new and modern (0-0)
gas turbine performance simulation industrial core tool called as PROOSIS
and 2) development in the form of a prototype demonstrator a multi-fidelity
simulation technology, fundamentally aiming to reduce engine development
cost and time.
The new and modern PROOSIS application framework conforms to an 00
programming schema giving the tool features in terms of flexibility,
extensibility, robustance, etc. Although, PROOSIS has been envisaged as a
long term development process, several of its current capabilities and
component modelling philosophies have been discussed in detail.
The prototype (3-D) integrated Aerodynamic Component Zooming Framework
makes the optimal use of two different simulation platforms at different fidelity
levels, thus allowing for variable' complexity analysis to be performed as
required. In order to demonstrate the prototype (3-D) integrated Aerodynamic
Component Zooming Framework a case-study has been developed. The case
study is to study the effect of VSV on a single stage compressor (or fan)
during part speed performance and which was successfully completed. The
integrated component zooming technique has been performed using a custom
developed workflow management tool referred to as "Integrated Workflow
Controller" making use of a distributed computing architecture.
The key contribution of the author within the scope the project and the thesis
has been the development of the modern object oriented GT (0-0) cycle code
PROOSIS framework and the development of the modern (3-D) integrated
aerodynamic compressor zooming framework. Within this thesis, full and
comprehensive information on the research work undertaken by the author in
order to achieve the above discussed goals, along with suitable results have
been presented. Also discussed in detail are results generated as a part of the
software testing, verification and validation of both 1) PROOSIS and 2) (3-D)
Integrated Aerodynamic Component Zooming Framework.
In an effort to reduce engine development cost and time as discussed earlier,
the research work undertaken by the author part of the CU team has made an
extensive and optimal use of modern, sophisticated and cross domain,
numerical simulation technology readily available and affordable, at different
fidelity levels. Additionally, the collaborative effort which has been another key
aspect of the project in creating a standard and a modem GT simulation
framework (with a prototype component zooming capability) for the advanced
gas turbine systems in future has also been achieved. This has been possible
by mutually sharing the technical expertise between all participating GT
industrial manufacturers, research centres and universities within the
European Union. It is the author's opinion that both of the above highlighted
developments form a strong foundation for future technological developments
leading to an even more sophisticated and capable, multi-disciplinary and
multi-fidelity simulation environment which will lead to a significant reduction in
engine development cost and time
Thermodynamic preliminary design of civil turbofans and variable geometry implementation
No full textImplementation of Variable Geometry during the off-design operation of an aero gas
turbine engine may cause deviations for restricted engine parameters when
fight envelope requirements are met. A method to optimize the thermodynamic
cycle of a engine with respect to fuel burn, while meeting a variety of airframe
or
technological restrictions at the three major operating points of the fight
envelope, namely the Top of Climb, End of Runway and mid-cruise points is
developed. Purpose is the comparison of engines on a common basis. The method
is
implemented and performance benefits are identified in a variety of studies,
such as:
o the theoretically infinite Variable
Geometry in turbomachinery components
o reduction of the turbine coolant fraction
during cruise for long range civil
fights
o
optimal variable nozzle geometry implementation during steady state and
transient
operation
Core of the
optimization procedure is a zero-dimensional engine arithmetic
solver
developed by the author from scratch for a 3-spool and 2-spool engine
configuration. The solver utilizes real gas properties and an approximate dimensionless
enthalpy rise profile at the fan exit for the separate modeling of the fan
tip and hub region. Purpose for the development of the new code has been a
common arithmetic treatment for
steady-state and transient calculations within
the same
engine solver, which is thoroughly described
Water ingestion effects on gas turbine engine performance
Full text linkAlthough gas turbine engines are designed to use dry air as the working fluid,
the great demand over the last decades for air travel at several altitudes and
speeds has increased aircraft’s exposure to inclement weather conditions.
Although, they are required to perform safely under the effect of various
meteorological phenomena, in which air entering the engine contains water,
several incidents have been reported to the aviation authorities about power
loss during flight at inclement weather. It was understood that the rain ingestion
into a gas turbine engine influences the performance of the engine and
particular the compressor and the combustor.
The effects of water ingestion on gas turbine engines are aerodynamic,
thermodynamic and mechanical. These effects occur simultaneously and affect
each other. Considering the above effects and the fact that they are timedependent,
there are few gas turbine performance simulation tools, which take
into account the water ingestion phenomenon.
This study is a new research of investigating theoretically the water ingestion
effects on a gas turbine performance. It focuses on the aerodynamic and
mechanical effects of the phenomenon on the compressor and the combustor.
The application of Computational Fluid Dynamics (CFD) is the basic
methodology to examine the details of the flow in an axial compressor and how
it is affected by the presence of water. The calculations of water film thickness,
which is formed on the rotor blade, its motion (direction and speed) and the
extra torque demand, are provided by a code created by the author using
FORTRAN programming language. Considering the change in blade’s profile
and the wavy characteristics of the liquid film, the compressor’s performance
deterioration is calculated.
The compressor and combustor’s deterioration data are imported to a gas
turbine simulation code, which is upgraded to calculate overall engine’s
performance deterioration. The results show a considerable alteration in
engine’s performance parameters and arrive at the same conclusions with the
relevant experimental observations
Turbine inlet temperature measurement for control and diagnosis in combined cycle gas turbine
No full textThe author was responsible for the Guarantee verification, testing and
eventually Acceptance of all of National Power's Combined Cycle Gas
Turbines for its commercial operation. It was discovered during the early
Acceptance Testing of these power stations that the Original Equipment
Manufacturers (OEMs) used empirical and indirect
~-~;
methods to derive the gas
turbine inlet temperature. This had direct impact on the life of the gas turbine
components and revenue earned in terms of increase in maintenance costs
and loss in generating power. It became absolutely imperative that alternative
methods should be quickly deployed on National Power's gas turbines to
substantiate or otherwise the already used indirect methods of running the
gas turbines.
A completely novel method of using ceramic thermocouples probes and
embedded ceramics onto blades to monitor elevated gas temperatures from
the early trials on large coal fired boilers to specially made burner rigs and the
Spey gas turbine are discussed. A patent for the ceramic temperature probe
was filed and approved. Finally, a non-intrusive infra-red thermal pyrometry
was installed on two of National Power's CCGT power stations. The report
includes technical aspects on emissivity, radiation, risks, obstacles
encountered, and the methodology used to install the pyrometry.
Using the data collated from Deeside Power Station, where two pyrometers
are currently installed, the results obtained from the engine simulation are
validated. Once the model was validated and the data correlated with the
actual data obtained, it can be concluded that the deployment of pyrometry
can control the diagnostics and operational behaviour of the CCGT plant. The
efficiency of the gas turbine was shown to increase by about 0:4% and the
corresponding increase in power was 1.3%, which would make a substantial
savings in the operating and maintenance costs to National Power. This was
estimated to be in access of £25,OOO,OOOlannum
Study of fuel cell and gas turbine hybrid power systems
No full textEnvironmental awareness and the interest in distributed generation caused by
electricity market de-regulation are factors that promote research on renewable energies.
Fuel cells transform the chemical energy stored in fuel into electricity by
means of electrochemical reactions. Among the different fuel cell types, high temperature
fuel cells (HTFCS) have many advantages: high efficiency, low emissions,
fuel flexibility, modularity and high quality waste heat. The main disadvantage is their
high cost - however, this will be reduced when HTFCS are commercialised.
The
synergy between HTFCS and gas turbines (GTS) makes HTPC/GTS very
efficient
power systems for the generation of electricity, from kilowatts to just a few
megawatts.
The
present work focuses on HTFC/GT power systems, analysing their
performance, studying some particular applications, and making an economic
assessment. The final objective of this Thesis is to define a procedure to assist in the
preliminary design of HTFC/GT systems.
The authors main contribution is the definition of the Green-Cell Code
capable of simulating HTFC/GT systems, the study of their interest for several
applications, and the generation of a decision-making method for the preliminary design
of HTFC/GT
systems.
The
design and off-design simulation of HTFC/GT cycles have been carried
out with the integration of a code developed by the author to simulate HTFC
performance, and a commercial code to simulate GT performance. This work is even
more valuable
given the lack of commercial tools to analyse the system.
All of the technical and economic work is collected in a set of charts that
assist the
procedure of HTFC/GT cycle selection.
These charts show that HTFC/GT systems currently achieve thermal
efficiencies of about 60%, and will be capable of achieving up to 73% in the future.
This is of great interest for power generation applications. The use of a recuperate is
required to optimise the performance of the gas turbine and the fuel cell; it is also
interesting to use it to generate the maximum amount of power from the HTFC, in order
to reduce emissions and increase overall efficiency. Results show that Pressurised
MCFC/GT
Cycles achieve better performance and economic results that Atmospheric
MCFC/GT
Cycles. For Pressurised MCFC/GT Cycles, the optimum stack operating
pressure is between 5 and 10 bars. The installation of a combustor in Pressurised
MCFC/GT
cycles leads to higher specific power, higher unit costs of electricity, higher
CHP
efficiency, and lower thermal efficiency.
The use of HTFC/GT
cycles to generate heat and power must be seen as a
way to improve HTFC/GT efficiency by using the waste heat of exhaust gases, rather
than as an
optimum application.
Results also show that SOFC/GT systems achieve slightly higher results than
MCFC/GT
systems. Thus, the choice between MCFCs and SOFCs will be based on
durability and cost issues rather than on performance issues
Preliminary aerothermal design of axial compressors
Full text linkThis dissertation documents a compressor preliminary design study conducted by the author
in fulfilment of his MSc thesis requirements. The compressor is intended for a new
development engine within the 20Klbf thrust category, planned to be used on a short-haul
aircraft, namely the ERJ-190.
A market research suggests that there exists a definite opportunity for a commercially
profitable engine within this thrust class. Furthermore, the proposed new engine is projected
to outperform current production engines on critical issues such as fuel efficiency and
operability.
By and large, the objectives of this work have been achieved and a compressor design and
layout is suggested, which matched or exceeded all the initial requirements. The quality of
the results from this study are thought to be of sufficient detail to allow a further, more
detailed development study to resolve some subtle pending issues. It is expected that, some
compressor stages may have to be altered slightly during detailed design to augment their
performance and ease of manufacture and assembly.
Throughout this study, the importance of the compressor design figure of merits, pertaining
to a short haul engine, has been outlined and their interaction on the design process is well
documented. Furthermore, some rather unorthodox objectives such as compressor
performance retention and reliability have been discussed. The author approached these
subjects in an innovative way due to the limited non-proprietary knowledge available on
these issues, especially considering their implications within preliminary design.
Furthermore, the author developed and tested a new preliminary turbomachinery design code,
named Turbodev, which can be used as an aid in future compressor design endeveours.
Turbodev can handle most types of compressor layouts and generates an overall aerodynamic
assessment of the turbomachinery performance.
In conclusion; this documentation and the associated literature review aim to provide the
reader with an overview of the work done and yield a better understanding of the decisions
that face any design bureau when developing a new or modified engine component.The research work disclosed in this publication is partially funded by the
Strategic Educational Pathways Scholarship Scheme (Malta). The
scholarship is part-financed by the European Union – European Social
Fund under Programme II – Cohesion Policy 2007-2013
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