nissan's european technology centre in cranfield, england uses maya's esc and tmg thermal and fluid flow simulation software to perform virtual testing for european vehicle design.
searing heat to sub-zero temperatures
imagine taking your car from the blistering heat of the arizona desert to the humidity of an amazon rain forest, then through the icy chill of an arctic winter. it may sound like a pretty grueling road trip to you, but to the engineers at nissan's european technology centre (netc) in cranfield, england, it's all in a day's work. netc is the design and development centre for nissan motors in europe and provides support to nissan's european manufacturing operations.
constantly on the lookout for ways to improve efficiency, quality, and time-to-market, netc is employing advanced technology to build digital prototypesto test their vehicles. using fluid flow and thermal simulation software allows engineers and designers to digitally test a virtual vehicle without building a physical prototype. applying simulation tools that enable engineers to examine new and existing designs from within their 3d mechanical design software is a key step towards attaining nissan's goals. simulating real-life conditions digitally can considerably reduce the time and expense of building physical prototypes to test every variation.
with maya's next generation esc electronic systems cooling and tmg thermal analysis tools, engineers can subject their models to real-world thermal conditions and see how they'll respond. they do all this from within the familiar environment of netc's mechanical design automation (mda) software. the use of enterprise-wide, integrated analysis tools has revitalized the creative side of engineering, allowing bright ideas to be built, tested and verified in hours instead of weeks. physical testing is often only needed when a final design is accepted and the first complete prototypes built.
"nissan's goal is to reduce vehicle development time by one third, so we must find ways of improving the test process and reducing the number of design iterations. the only way we can do this is with virtual testing using simulation tools."
nissan european technology centre
in the heart of rural england, engineers at nissan european technology centre in cranfield
can recreate the searing heat of the arizona desert, the humidity of a tropical rain forest,
or the chill of a sub-zero arctic winter - from one extreme to the other in just 3.5 hours.
virtual vehicle testing
kevin puddephatt is a test engineer at netc cranfield. in addition to acting as a test and analysis resource, his team adapts car models to european requirements. among the more common design tasks performed at netc cranfield are modifications to the heating, ventilation and air conditioning (hvac) and engine cooling systems. since changes to these systems can have profound effects, designs require considerable prototyping and testing before they are certified for use in production vehicles. the netc engineering team realized that digital simulation could greatly accelerate that process.
kevin recently discovered the advantages of using maya's esc and tmg packages to examine the effects of his modifications. for him, the experience was nothing short of revolutionary. "we're looking at a fundamental change in our business over the next couple of years," he says and he couldn't be happier.
before satisfying himself that maya's packages best addressed his needs, kevin put several tools through their paces. "we were looking for something our engineers would be comfortable with," he explains. "esc seemed a lot easier to use than any of its competitors." also, maya's analysis packages communicated perfectly with the rest of nissan's mda environment. "maya's analysis tools made the most sense since they're well integrated with 3d design."
an added advantage was the fact that some of nissan's european suppliers had also made the switch to i-deas. "i could use a vent from one supplier and a heater from another supplier, then build up a model without having to mix-and-match mcad systems."
it didn't take the team long to confirm that they were making the right decision. they had a number of issues concerning the driver's side air vent on one of their european sedans. modeling, testing and fixing the part had taken two months. as part of the evaluation process, they put the issues to esc. "when we gave the information to maya in order to benchmark esc, they returned exactly the same result within a few days. we realized that with the help of esc we could have solved it in two weeks. we were looking at a time saving of 80%."
the initial design of the side air-vent for the european primera did not adequately redirect airflow.
esc duplicated the concern found during product testing. this image shows flow from the air vent.
the ducting leading up to the air vent, the vent geometry and louvers as well as the vehicle
interior around the vent were successfully modeled using esc.
the breakthroughs kept coming. while training to use the new software, kevin's team of engineers tackled one of their more vexing problems; the airflow through their semi-anechoic chassis dynamometer chamber (an acoustically shielded testing space for noise and vibration monitoring) was uneven.
this chamber was also designed to perform as a wind tunnel for testing of various automotive parts, so maintaining an even airflow was vital. the hardest part of the problem was just discovering what the airflow looked like at the time. "just getting the data to model what the chamber flow was doing took at least two weeks. i had a technician in the chamber measuring airflow on a 100mm grid at various distances from the nozzle. it was incredibly tedious and time consuming, but i needed to know where the air was going."
using esc, the netc engineers were able to model the chamber in a few hours. "the software immediately showed us the current conditions," remarks kevin, "an exact copy of our experimental results." the rest of the afternoon was spent addressing the flow concerns in the chamber: modeling a variety of different air guides, meshing them, and solving.
"we did three or four different air guides that afternoon, and very quickly honed in on what we had to do. without esc, the only way to solve this was to physically place different air guides in the chamber and do the measurements again, each of which would take another two weeks."
in order to make modifications to netc's semi-anechoic chassis dynamometer test chamber,
the engineers modeled the chamber using esc. the software accurately predicted the flow conditions
and quickly lead to a solution. by modifying the inlet air guides, the test chamber flow was corrected
for better flow distribution across the front of the test vehicle.
the images show air speed contours.
nissan's future is digital prototypes
kevin says that esc and tmg successes have continued unabated, with a variety of different issues under investigation. projects include redesigning hvac ductwork for the new european almera, headlamp heating analysis, and more challengingly, modeling airflow around the fenders of a new car model and examining its impact on radiator cooling.
the applications don't stop there. "we plan to use it for warm-up and cool-down tests," says kevin, "simulating solar radiation on the vehicle for air conditioning development. we also plan to use tmg to simulate radiative heating from the exhaust systems to other areas of the engine. the engine group plans to use esc and tmg to model the airflow in and around the exhaust manifold, and the heat transfer from exhaust gasses to the manifold. they may want to use thermal analysis results to predict manifold stresses and prevent cracking. the chassis group may be using it for heat shield development."
it's clear that virtual vehicles and digital thermal testing are paving the way for the future of automotive thermal engineering. "our plan is to digitally simulate the physics for the entire vehicle", comments kevin, and with maya's simulation technology fueling the future, "the sky's the limit!"
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