The University of Limerick is helping to keep Airbus aircraft - particularly the wings - cool, writes Anna Nolan
A research team at the University of Limerick has helped to keep Airbus flying high by keeping its aircraft wings cool. Its study of wing designs helped confirm Airbus's modelled information about how to prevent wings from overheating while on the ground.
Overheating of wing-mounted electronic components can lead to their failure. This isn't a problem during flight given the cold temperatures at high altitudes, but things can get fairly warm while the plane stands on the runway on a hot day.
Airbus asked UL's Stokes Research Institute to study temperatures inside the wing when the ambient air temperatures were above 35 degrees Celsius. The company also wanted proof its existing computer modelling techniques for heat flow in wings matched the physical facts.
Airbus uses passive cooling techniques as a way to avoid the extra weight of cooling fans and pumps. And passive cooling relies on suitable mechanical design.
"With passive cooling, natural convection alone is used to control the temperatures of the electronic components and their enclosures within the aircraft wing compartments," explains Dr Vanessa Egan, a research fellow at the Stokes Research Institute.
Based in UL's Mechanical and Aeronautical Engineering Department, Stokes wins almost all of its research funding in open competition and receives funding from Airbus and IRCSET.
"It started in 2003 with the AHLPACS (Advanced Heat Load Predictions for Aircraft Composite Structures) programme, with Dr David Newport leading the work and David Jones as Research Assistant," explains Egan. "I took over from David in April 2005."
AHLPACS involved the design and manufacture within Stokes of several test aircraft compartments, including wing boxes. One of the specialties of the Stokes Institute is experimental fluid dynamics, expertise that allowed them to obtain detailed velocity and temperature measurements inside these test compartments.
The velocity of the airflow within the heated compartments was studied using Particle Image Velocimetry (PIV). PIV works by introducing tiny nanoparticles into the air stream and then using a laser to light them up. A camera takes timed pictures that provide speed measurements. Special software then analyses the data to produce colour-coded images on a computer screen.
The advantage of using PIV is that it is a non-intrusive technique that provides real-time results, explains Egan. "We can measure the velocities at every location."
The test compartments contained a bleed duct, a hollow tube. Although nearby hot engine gases did not enter the compartments, they heated up the bleed duct, and a heated plume rose from it.
This in turn controlled the heating within the wing compartment. The behaviour and influence of the plume was studied at different temperatures, and with the duct in different locations.
"We found that the velocities matched very well with the numerical analysis of the Airbus computer model and our own computer models," says Egan. The validation of the Airbus computer models was important in the successful introduction of the A380.
Dr Egan's work also showed the compartment could be kept much cooler by placing the bleed duct in a different location. This is to be studied in a new Stokes/Airbus project, which she is supervising.
"In the new project, which started in January this year, we are looking at more complex calculations over a greater area of the wing," she said.