R-15451-2010 The evaluation of engine performance at high altitude
THE EVALUATION OF ENGINE PERFORMANCE AT HIGH ALTITUDE
When designing engines that have to operate at a certain altitude above sea level,
it is necessary to take into account those changes that occur in temperature and
atmospheric pressure as altitude increases. Such variations affect air composition
and density, and all these parameters affect the engines’ performance.
Researchers at the Universitat Politècnica de València’s ‘CMT-Motores Térmicos’
Institute have developed a test facility that simulates the pressure and temperature
conditions at high altitude of the air that is sucked into a reciprocating internal
combustion engine, and evaluates the engine’s performance.
The following figure shows an engine of this kind installed in an aircraft in service.
In it we can see the air intake and the exhaust gas discharge; it is the pressure and
temperature conditions at which these processes occur that the facility designed by
the researchers at the ‘CMT-Motores Térmicos’ Institute aims to simulate.
These simulations help prevent possible malfunctions of the engine under certain
conditions, as engines can be tested in the laboratory before they are used on the
plane in actual service conditions. They also make it possible to optimize fuel
consumption –which is affected by the characteristics of the air that is sucked into
the engine–, reduce polluting emissions and check whether a given engine part is
working properly.
This facility can also be used to evaluate the performance of those engines that are
used for ground transportation at a high altitude. For example: transportation in the
mountains, mining or any other industrial activity at a high altitude above sea level.
The test facility can be configured according to different versions incorporating
different components, whose complexity depends on the energy savings to be
achieved. The following figure shows both the simplest implementation and the
most complex one of those patented; the item (1) represents the engine under test,
p1, p2 and T1 are the flight conditions that the facility is expected to reproduce, and
A1 represents sea level conditions, which are those at which the facility and the
laboratory find themselves.
R-15451-2010 The evaluation of engine performance at high altitude
The remaining elements (turbo groups, vacuum pumps, heat exchangers, heaters
and particulate filters) have to be properly combined and controlled in order to
achieve the specified purpose.
DESCRIPTION
The need to establish fixed conditions of pressure and temperature in the
atmosphere according to altitude which can be used for developing and tuning
engines or other aircraft components led the International Civil Aviation
Organization (ICAO) to define the international standard atmosphere (ISA) in 1952.
In order to study the effect of altitude on the processes of combustion and pollutant
formation in an engine it is necessary to take into account the extreme variations in
pressure and temperature that occur at the heights at which aircraft fly. Such is the
case of small unmanned aircraft that can reach tropospheric flight conditions with
relatively small engines. As an example, up to 11000 m (i.e., the tropopause) the
temperature drops at a rate of 6.5ºC per 1000 m, there reaching a temperature of –56.5ºC
and a pressure of 225 mbar.
Researchers at the Universitat Politècnica de València’s ‘CMT-Motores Térmicos’
Institute have developed a test facility that, with a low energy cost, simulates the
pressure and temperature conditions, according to altitude above sea level
(following the specifications of the ICAO’s ISA), of the air that is sucked into an
engine, and evaluates the engine’s performance.
R-15451-2010 The evaluation of engine performance at high altitude
Versions and graphs
The researchers at the ‘CMT-Motores Térmicos’ Institute have conducted several
tests of the new device, so as to ensure that it functions properly. These tests have
also shown the device’s versatility –as it can be controlled in order to simulate
different altitudes– and its low construction and operating cost, with regard to the
current state of the art.
STATE OF THE TECHNOLOGY
The research team has conducted several tests using numerical simulation and a
first prototype. In this way it has shown that the device proposed in the patent is
able to reproduce the pressure and temperature conditions, according to altitude
above sea level, of the air that is sucked into a reciprocating engine. The following
figure shows an example of how several different engine operation variables would
evolve over time until they reached the desired conditions for testing the engine: at
about 10000 m above sea level (with the intaken air at –50ºC and 304 mbar). The
figure also shows how the speed of the turbine used to cool the air increases up to
80000 rpm as the intake air mass flow grows up to 0.2 kg/s, which is a typical value
of light aircraft and small unmanned aircraft.
Plenum stagnation temperature [ºC]
Turbocharger speed [rpm]
100000
80000
60000
40000
20000
0
0
1
2
3
Time [s]
4
0.196
0.192
0.188
0.184
2
3
Time [s]
4
-10
-20
-30
-40
-50
-60
0
Plenum stagnation pressure [bar]
Intake air mass flow [kg/s]
0.2
1
0
5
0.204
0
10
5
1
2
3
Time [s]
4
5
0.314
pamb = 1.027 bar
Tamb = 20ºC
0.312
0.31
0.308
0.306
0.304
0.302
0
1
2
3
Time [s]
4
5
R-15451-2010 The evaluation of engine performance at high altitude
APPLICATIONS
• Testing of reciprocating internal combustion engines at centres where such
engines are manufactured or developed, when the simulation of the engines’
operating conditions at high altitude in both ground and air transportation is
required.
o Analysis of pollutant emissions.
o Analysis of engine consumption.
o Effects on engine performance of snow and/or ice formation.
o Global analysis of engine performance (torque and power).
o Analysis of engine components such as the air filter or the turbo.
• In aircraft design, the device can be used for developing and/or optimizing small
engines in private jets and/or small unmanned aircraft.
ALTERNATIVE PRODUCTS
There are currently no other devices that simulate pressure and temperature
conditions with the same characteristics as the system patented by the UPV.
To date, engine performance in high altitude conditions has been studied either
through the theoretical modelling of how they work or through in-situ tests carried
out at high altitude.
In the case of the engines of land vehicles travelling at high altitude, alternative
devices separate the process of cooling (with refrigeration units) from that of
vacuum generation (with specific pumps), which makes them much more
expensive.
In the aircraft industry, for example, analyses of the behaviour of aircraft engines at
high altitude are carried out. Such tests take place in large chambers within which,
thanks to a vacuum pump, the temperature and pressure conditions that occur in
air navigation are reproduced. The cost of achieving these operating conditions, the
equipment and the facilities needed is very high.
ADVANTAGES
•
The device’s dimensions are small.
•
The system can be used for different kinds of tests. A variety of different
configurations can be integrated into a single reconfigurable facility.
•
The cost of the parts and, therefore, of the whole set, is small.
R-15451-2010 The evaluation of engine performance at high altitude
•
Energy consumption is lower than in any of the alternative or equivalent
solutions.
•
It keeps the advantages of other devices and incorporates additional
improvements in implementation, maintenance and operation costs, which
makes it a unique device on the market.
•
Cost reduction in parts.
INTELLECTUAL PROPERTY
On January 31, 2011, the Universitat Politècnica de València applied to the
Spanish Patent and Trademark Office for patent protection, and was given the
reference P201130120.
COOPERATION DESIRED
The UPV is looking for companies interested in negotiating patent license
agreements for the device and marketing it.
PROFILE OF THE CMT-HEAT ENGINES INSTITUTE
The research work of the ‘CMT-Motores Térmicos’ Institute focuses on issues
related to reciprocating internal combustion engines, and more particularly, on
improving their performance.
The Institute’s studies in recent years have focused on thermo- and fluid-dynamic
processes in reciprocating internal combustion engines, especially on the
processes of air charge renewal and management; on those of injection,
combustion and pollutant formation (especially in direct injection diesel engines); on
the control of the noise that these processes generate; and on the thermal
management of engines.
Researchers at the ‘CMT-Motores Térmicos’ Institute also work on developing nonintrusive diagnostic techniques for predictive maintenance, such as performance
measurement, lubricant analysis, and analysis of the vibration of the block. Another
of their main lines of research is the implementation of integrated maintenance
systems in transportation fleets.
The Institute intends to combine basic studies, aimed at better understanding and
predicting all relevant aspects related to the topics of study, and applied
developments, aimed at enabling technology transfer to industry and solving
concrete problems –in order, ultimately, to reduce consumption, reduce
environmental aggression and increase engine reliability.
In this regard, it is noteworthy that the Universitat Politècnica de València’s ‘CMTMotores Térmicos’ Institute collaborates with the leading automotive companies
R-15451-2010 The evaluation of engine performance at high altitude
worldwide, including BMW, Centro Ricerche FIAT (CRF), Delphi Diesel Systems,
Ford Forschungszentrum Aachen, General Motors, PSA Peugeot Citroën, Renault,
Renault VI Powertrain, and AVL.
AREA
Engines
CONTACT
Elsa Domínguez Tortajada
[email protected]
Universitat Politècnica de València
Technology Transfer Centre
Edificio 6G
Camino de Vera s/n, 46022- Valencia