Success Stories: Ariane 5 Rocket
GridPro used in the development of the highly successful Ariane 5 rocket.
Arianespace is currently the world's largest
commercial satellite launcher.
Much of its success is due to the Ariane-5 launch system.
Araine-5 has broken many recent records in the commercial launching of
satellites,
including the largest number of successful commercial launches in a year,
and highest payload carried by a commercial launcher
Even though Ariane-5 is arguably the most successful commercial
rocket-launcher,
the design of the Ariane-5 rocket faced many challenges in the beginning.
The Ariane-5 rocket has to produce enough thrust to accelerate an 8 ton
satellite to more than 25000 Mph
and have enough control to place it in a geo-stationary orbit above the
earth.
The engineering challenges in the design stem from immense mechanical loads,
hypersonic flows,
huge variations in temperature and pressure, instability problems and many
other design challenges which require superior engineering solutions.
Many specialized design tools and sophisticated experiments were used in the
design of Ariane-5.
One of the major design challenges involved the aero-thermodynamic analysis
of the rocket and the whole launch system.
Aero-thermodynamic analysis involves the combination of the study of flow
and heat transfer relations,
and also involves calculation of reacting flow when integrating the
combustion system.
Accurate analysis of the flow and heat-transfer are key to controlling the
choice of the trajectory, guidance, navigation,
and also for the thermal-protection systems, propulsion systems and
performance of the launch system as a whole.
Computational fluid dynamics (CFD), which involves the computational
modeling of the aero-thermodynamics, was a powerful tool in the design
process.
CFD was used for studying many aspects of Ariane-5 performance and design.
This included the overall drag assessment during takeoff, unsteady buffeting
loads at transonic speed, maximum steady state load at around Mach 2,
booster separation, jet-impact during staging, solid booster radiation, and
studying local aerothermodynamics such as local heating.
The need for high accuracy required not only a very robust CFD software to
solve the complex aero-thermodynamic flow,
but also extensive validation by experiments and a superior grid generation
package.
Modeling complex flow at high accuracy requires very high quality grids.
GridPro was chosen as the main grid generation software for the European
Space Agency's (ESA) Aero-thermodynamics group because of its ability to
produce very high quality multi-block grids on complex geometries.
Martin Spel was one of the engineers at the European Space Agency's
Department of Aerothermodynamics, performing CFD simulations on space
vehicle
geometries. He stated: "It was clear that GridPro was the only grid
generation software which could fit our needs here. When you have complex
geometry,
and require a high quality grid for computations in transonic, supersonic
or hypersonic flow, GridPro is the clear choice.
Other grid generation software just cannot maintain the same level of grid
quality when the geometry becomes as complex as the Ariane-5 launch system".
Apart from using many commercial CFD codes, computations on GridPro grids
were performed with "Lore", which has been developed specifically
to model heat transfer and flow at such high speeds. The figure shows a
GridPro grid on the Ariane-5 launcher and the corresponding pressure
solution
calculated by Lore. The complex flow calculated is also shown as velocity
vectors in the next figure.
An experimental setup of a model of the Ariane-5 was setup to validate the
results produced and the CFD results were validated.
It was found that GridPro enabled the CFD codes to produce accurate results
and get the best out of their CFD codes.
Apart from the successful use of GridPro to model the entire launch system,
GridPro is also being used at the ESA to model many other designs and
space vehicles. A recent calculation performed on the X-38 space vehicle is
shown here.
Apart from superior quality of results, another advantage of using GridPro's
grid generation system is the ability to
model small changes in the flap movement in X-38 automatically to study the
effects of flap deflection. This is illustrated in the figure.
GridPro enabled the European Space Agency to achieve superior results on
Ariane-5 leading to better analysis and insight in the design.
To learn how GridPro can help you achieve similar success, please contact
us.
References: http://www.esa.int/esapub/bulletin/bullet105/bul105_7.pdf
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