Diapositiva 1

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Propulsion and Power for 21 st Century
Aviation
Propulsion systems II
Rafael Cerpa Bernal
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INTRODUCTION

• In the New millennium we will require
  revolutionary solutions to increase
• Safety
• Reliability
• Environmental Compatibility
• Affordability
• The vision for the 21st century aircraft is to
  develop propulsion systems
• Intelligent
• Highly efficient
• Virtually inaudible
• Have zero harmful emissions (Co2 and Nox)

Propulsion systems II
Rafael Cerpa Bernal
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INTRODUCTION

• Possible solutions
• Intelligent engines capable of adapting to
  changing internal and external conditions, to
  optimally accomplish missions with either minimal
  or no human intervention.
• Change the typical configuration of engines, for
  a large number of small, mini, or micro engines.
• Pulse detonation engines (PDE).

Propulsion systems II
Rafael Cerpa Bernal
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MISSION
SAFETY Reduce aviation's fatal accident
rate. EMISSIONS REDUCTION Reduce Nox emissions by
70 within 10 years and by 80 within 25
years. Reduce No2 emissions by 25 within 10
years and by 50 within 25 within years. NOISE
REDUCTION Reduce perceived noise levels of future
aircraft by a factor a 2 (10 decibels) within 10
years and by a factor of 4 (20 decibels) within
25 years CAPACITY Triple the capacity of the
aviation system within 25 years (compared with
1997)
MOBILITY Reduce the intercity (door to
door)flight time by half in 10 years and two
thirds in 25 years, and in intercontinental
flights by a half in 25 years.
Propulsion systems II
Rafael Cerpa Bernal
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AEROPROPULSION VISION 21st CENTURY AVIATION

• During the past five 5 years, NASA has developed
  a different new ideas about the future of the
  aviation industry, and the most important the
  possibility of reduce the emission and the noise
  produced by the aircraft engines.
• NASA vision 21st century aviation
• The gas turbine revolution.
• The engine configuration revolution.
• The fuel infrastructure revolution.
• The alternate energy and power revolution.

Propulsion systems II
Rafael Cerpa Bernal
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GAS TURBINE REVOLUTION
The industry wants that in the future the engines
will be self-thinking, self-adjusting (Without
human intervention), and able to operate at
optimal conditions to achieve pre-specified
customer requirements during the entire ground
and flight envelope. The first generation of high
by pass turbofan engines introduced in 1985 were
designed to meet the energy crisis challenge, and
incorporated the first generation of superalloy
materials, ceramic coatings and polymer matrix
composites. The second generation aircraft gas
turbine engines, introduced prior to 1995, had
continued emphasis on
fuel burned reduction, this HBPR turbofan engines
incorporated a new advanced materials for still
the high cycle temperature and pressures that
resulted in greater core specific power and
overall efficiency . The next generation turbine
engine technologies will be focused in the
following three strategic areas Intelligent
computed and controls strategies, smart
components and adaptive technologies and systems
Propulsion systems II
Rafael Cerpa Bernal
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INTELLIGENT COMPUTING AND CONTROL STRATEGIES
In addition to current efforts on physics based
modelling for multidisciplinary (Aerodynamic,
thermodynamic, and structural) analysis of
propulsion systems. In the figure we can see an
integrating diagram such thermodynamics,
aerodynamics, structures, heat transfer, etc. It
captures the concept of numerical zooming between
zero dimensional to one two and three
dimensional analysis codes. It is used in the
different parts of the engine (Fan, Compressor,
CC, Turbines, etc).
Propulsion systems II
Rafael Cerpa Bernal
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INTELLIGENT COMPUTING AND CONTROL STRATEGIES
In the area of sensors and controls, future
research will transform recent successes in
physics based multidisciplinary modelling into
real time propulsion health monitoring and
management for improved safety and reduced
maintenance costs. The engine will sense the
different engine and environmental parameters and
will change another's parameters and the engine
performance will increase, all changes must made
in real-time.
Propulsion systems II
Rafael Cerpa Bernal
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INTELLIGENT COMPUTING AND CONTROL STRATEGIES
We can detect possible future failures using this
kind of system also we can increase the
performance of the engine, in the different
flight stages.
Propulsion systems II
Rafael Cerpa Bernal
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TROUBLESHOOTING PW100 ENGINE
POSIBLE FAILURE
PARAMETERS
ITT/TG
NH
NL
WF
Air inlet blocked Possible FOD located in the
impeller Possible failure in measure elements
Propulsion systems II
Rafael Cerpa Bernal
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SMART COMPONENTS FOR NOISE AND EMISSION REDUCTION
NOISE REDUCTION For noise reduction, the engine
components than need to be studied are the fan,
inlet and exhaust nozzle. Aspirated fans with
trailing edge blowing have shown significant
reduction in rotor-stator interaction as well as
broad band noise. The figure shows a model of a
composite hollow rotor blade with the pressure
side skin removed to show internal flow passages.
The passages are designed to deliver the injected
flow at the design pressure and flow rate.
Propulsion systems II
Rafael Cerpa Bernal
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SMART COMPONENTS FOR NOISE AND EMISSION REDUCTION
Aspirated fans and compressor stages with
boundary layer suction, active or passive, can
help to drastically reduce the rotor speed for
the same pressure ratio. Inlet and nozzle
technologies will focus on noise reduction and
propulsion system operability impacts. Advanced
modelling techniques will allow designers to
capitalize on natural acoustic phenomena to
reduce the observable noise footprint of future
aircraft such that it is contained within the
airport boundary.
Propulsion systems II
Rafael Cerpa Bernal
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SMART COMPONENTS FOR NOISE AND EMISSION REDUCTION
NITROGEN OXIDE EMISSION REDUCTION Demands for
reduce NOx emission while increasing performance
have resulted in advanced combustor designs that
are dependent on effective fuel-air. Due to non
uniformities in the fuel-air mixing and the
combustion process, hot areas that can be zones
of increased Nox formation exist in the combustor
exit plane, The elimination of hot streaks can
contribute to emission reduction. If we can
obtain air-fuel mixture ratio near
stoichiometric, we can minimize the formation of
monoxide carbon and unburned hydrocarbons. In
the figure we can see a new fuel injector concept
which containing multipoint fuel injection tips
and multiburning zones was developed to reduce
NOx emissions.
Propulsion systems II
Rafael Cerpa Bernal
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SMART COMPONENTS FOR NOISE AND EMISSION REDUCTION
CO2 EMISSIONS REDUCTION While NOx reduction will
require advanced combustion technology, the CO2
emissions are focused on reducing fuel burn
through increased performance and efficiency.
Propulsion system performance can be improved by
improving engine thermal efficiency and
propulsive efficiency. Higher by pass ratio is
the key to improving propulsive efficiency. Use
of aspirated fans, and core-drive-fans are 2
concepts being investigated to increase the
engine by pass ratio.
Various component efficiencies and overall engine
pressure ratios and temperature need to be
increased significantly to obtain a higher by
pass ratio (551 601) and with inlet turbine
temperatures exceeding 1700ºC.
Propulsion systems II
Rafael Cerpa Bernal
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ENGINE CONFIGURATION REVOLUTION
DISTRIBUTED ENGINES The distributed propulsion
concept is based on replacing the conventionally
small number of large size, discrete engines with
a large number of small, mini, or micro
propulsion systems. Distributed propulsion
broadly describes a variety of configurations
that can be classified into three categories
small, mini and micro engine system. Distributed
engine concepts will enable a variety of
attractive airframe configurations leading to
performance and operational
benefits. Large engine production rates, lower
development cost and cycle time, and elimination
on the wing engine maintenance by replacing
entire engines could reduce the life cycle cost
by as much as 50.
Propulsion systems II
Rafael Cerpa Bernal
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ENGINE CONFIGURATION REVOLUTION
COMMON CORE MULTI FANS PROPULSORS Common core
multi fans propulsors are multiple thrust fans
powered by a central engine core. The advantage
of these configuration is that they provide ultra
HBPR engines with higher propulsive efficiency
without necessitating radical airframe changes to
accommodate a single large turbofan engine.
Propulsion systems II
Rafael Cerpa Bernal
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ENGINE CONFIGURATION REVOLUTION
DISTRIBUTED EXHAUST Propulsion systems with
distributed exhaust use a central engine power
plant with a ducted nozzle (s) for strategic of
thrust on the aircraft. Distributed exhaust
configurations suffer performance penalties as a
result of nozzle viscous losses and likely only
will be used for aircraft systems exhibiting
extreme sensitivity to low speed lift and/or
cruise drag. Therefore, distributed exhaust
systems will be better suited to supersonic
cruise applications in which noise sizing for
take off field length and sustained supersonic
cruise drag are the most dominant and least
reconcilable constrains.
Propulsion systems II
Rafael Cerpa Bernal
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ENGINE CONFIGURATION REVOLUTION
BLENDED-WING-BODY AIRCRAFT WITH DISTRIBUTED
PROPULSION To demonstrate the feasibility of
propulsion systems using embedded wing engines,
an 800 passengers BMW transport aircraft with
engines distributed along the wing span. The
figure shows a configuration with engines buried
inside the wing between the payload volume and
the outer wing. This configuration has inlets and
nozzles near the wing leading edge and trailing
edge respectively, and provides direct powered
lift using thrust-vectoring nozzles.
Propulsion systems II
Rafael Cerpa Bernal
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ENGINE CONFIGURATION REVOLUTION
DISTRIBUTED PROPULSION CONCEPT FOR SUPERSONIC
TRANSPORT In a supersonic flight, added drag
(wave drag) results from the shock waves
generated by the vehicle. Depending on the
vehicle configuration, this wave drag may
constitute from 10 to 50 of the overall vehicle
drag. Shock waves will coalesce to varying
degrees to cause a sonic boom at the ground. For
this concept, two conceptual propulsion systems
are being considered traditional gas turbine
engines, and a novel propulsion system, utilizing
distributed power and perhaps electric fuel cell
power. To produce the required lift, additional
sweep wing panels outboard of the engine nacelle
panels may be required.
Propulsion systems II
Rafael Cerpa Bernal
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ENGINE CONFIGURATION REVOLUTION
PULSE DETONATION ENGINES PDE's have potential as
a revolutionary means for achieving low cost,
high efficiency propulsion. PDEs operate quite
different from gas turbine engines in the process
of producing thrust. While a gas turbine engine
must utilize some of its energy to mechanically
compress air prior to increasing its temperature
during combustion, PDEs utilize energy from
detonation waves (Mechanical shock and combustion
waves) to accomplish P and ºT increases.
The PDEs cycle uses constant volume combustion
and potentially can be more efficient than the
constant pressure cycle used in gas turbine
engines.
Propulsion systems II
Rafael Cerpa Bernal
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ENGINE CONFIGURATION REVOLUTION
NASA studies are underway to utilize pulse
detonation combustion in a hybrid gas turbine
engine for subsonic commercial aircraft
applications. These studies consider the
potential system level benefits of using PDEs
instead of current propulsion systems, including
improved efficiency and SFC, as well as the
potential for configurations variations and
airframe integration benefits. An advanced
hybrid PDE concept in which the conventional
combustor is
Replaced by a PDE. Initial studies have indicated
a potential for 10 or more reduction in cruise
SFC. Some key technology issues that need to be
resolved prior to this technology's application
include the following Detonation frequency,
Structural robustness and fatigue, noise
associated with hybrid PDEs, NOx emissions,
thermal management and integrated issues.
Propulsion systems II
Rafael Cerpa Bernal
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FUEL INFRASTRUCTURE AND ALTERNATE ENERGY AND
POWER REVOLUTION
HYDROGEN POWERED GAS TURBINE ENGINE The concept
of hydrogen powered gas turbine A/C has been
around for over half century. A number of
hydrogen based propulsion systems and A/C
concepts for subsonic and supersonic flights. The
hydrogen is one of the most common elements, but
it is not found in a pure state and must be
produced from some other source such as methane
or water. The program concentrates on 5 critical
areas Production, Delivery, storage, conversion
applications and public education.
In general terms the properties can be put in the
following context - Hydrogen has 2.8 times the
energy per pound as Jet A, and 2.4 in comparison
with methane. - For equivalent energy, Hydrogen
has 4 times the volume of Jet A . - Hydrogen has
4.9 times the cooling capacity of Jet A.
Propulsion systems II
Rafael Cerpa Bernal
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FUEL INFRASTRUCTURE AND ALTERNATE ENERGY AND
POWER REVOLUTION
The most immediate impact a switch to hydrogen
will have on A/C is on the design itself. Due to
its low volume, even in liquid state, design
changes must be made to the propellant storage
system. Fuel no longer can be stored easily in
wing fuel tanks. A potential NASA concept based
on the modification of Boeing's Sonic Cruiser
design with tanks located forward of the engines.
The switch to hydrogen fuel has some advantages
for A/C designs. Due to hydrogen's higher heating
value, the amount of fuel mass required is lower.
The result is a net decrease in aircraft gross
take off weight (GTOW). Some studies indicate a
53 reduction in GTOW.
Propulsion systems II
Rafael Cerpa Bernal
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FUEL INFRASTRUCTURE AND ALTERNATE ENERGY AND
POWER REVOLUTION
STORAGE AND DELIVERY SYSTEM One of the biggest
challenges to hydrogen aircrafts is storage.
Issues whit hydrogen's volume not only affect
basic aerodynamic design, but also impact basic
vehicle structure. We can found a different
options purposed for tank structural integration,
insulation, and material selection.
The processes to load and manage hydrogen onboard
A/C will require new methods to be developed.
Advances in automated fueling equipment can
improve the safety and efficiency of the fueling
process.
Propulsion systems II
Rafael Cerpa Bernal
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FUEL CELL BASED POWER AND PROPULSION
Recent studies conducted at NASA indicate that
fuel cells are becoming a viable option for small
aircraft propulsion, (UAVs), and (APUs), and hold
promise for future large-scale commercial
aircraft. Doubling of fuel cell power densities
can be achieved in the next five years, which
would make electrically powered, light, general
aviation aircraft possible with no performance
penalties compared to their conventionally
powered counterparts.
Preliminary results from a recent NASA study
indicate that the flight is possible using
commercial off-the shelf fuel cell and power
management technology levels, albeit at reduced
speed, climb rate, range and payload carrying
capability.
Propulsion systems II
Rafael Cerpa Bernal
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FUEL CELL BASED POWER AND PROPULSION
Electrically powered subsonic transports of the
future likely will be powered by small,
distributed motors and fans. Similar to
wing-span distributed engines, these
configurations will utilize remote fans and
motors to achieve forward propulsion, and may be
coupled with blown wing/flaps for high lift at
takeoff. The primary advantage of these
configurations is the use of a centralized,
highly efficient core power unit, which may be in
the form of fuel cells or centralized gas turbine
APUs.
Electric power transmission to the remote fans is
a safer, more efficient approach than
independent, distributed fuel delivery systems.
Propulsion systems II
Rafael Cerpa Bernal
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FUEL INFRASTRUCTURE AND ALTERNATE ENERGY AND
POWER REVOLUTION
The major technology being addressed for the
advanced application is superconducting or
cryogenic motors cooled by liquid hydrogen fuel.
One significant activity is to develop and test a
10 hp cryogenic motor. In addition, NASA is
investigating a 450 hp, LH2 cooled motor design.
The goal is to develop cryogenic air-core
propulsion motors to eliminate the massive weight
of traditional iron core motors. NASA is also
developing cryogenic motor controllers for power
conditioning to reduce weight and radio frequency
electromagnetic interference.
Propulsion systems II
Rafael Cerpa Bernal
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FiN
Propulsion systems II
Rafael Cerpa Bernal