Case Studies/Success Stories

Germany's DLR Institute of Propulsion Technology

Dr. Frank Eulitz
Head of Numerical Simulation,
DLR Institute of Propulsion Technology

German Researchers Explore New Possibilities in Propulsion with Sun Technology

In 1903, the Wright brothers sought a windy location to test the world's first motor-driven "aeroplane." Almost one hundred years later wind, or air flow, still keeps airplanes flying, but the process for creating them has changed radically. Today, wind tunnels are the principal tool scientists use to simulate air flow patterns and their impact on airplane and spacecraft designs. Unfortunately, they are costly, complex and limited in the information they provide.

Other aspects of the traditional airplane development process are also inefficient. After creating a design concept, scientists create a prototype, build a test rig, test it in a wind tunnel, modify the concept, build a new test rig, test it again and repeat the cycle over a span of months or years. Thankfully, this tedious process is changing with advances in computational fluid dynamics (CFD). Simply put, CFD numerically simulates the air flow that influences an object as it moves, enabling scientists to test models in a "numerical wind tunnel" where calculations predict the effects of unsteady air flows. Designs can be checked out before building a prototype, saving tremendous amounts of time and money. When used in conjunction with the right computing systems, CFD can cut development cycle times by 50 percent or more.

A small group of turbomachinery aerodynamicists at Germany's National Aerospace Center's (DLR) Institute of Propulsion Technology are demonstrating the feasibility of CFD with today's high-performance computing technologies. They are running DLR's premiere CFD turbomachinery application, TRACE (Turbomachinery Research Aerodynamic Computational Environment), on a Sun system to perfect a new type of engine called a shrouded propfan. Shrouded propfans combine technologies from propeller and turbo jet engines, enabling travel at the speed of jet aircraft, but consuming less fuel. Both civil and military aircraft can benefit from aerodynamic technologies used in propfans, but not until scientists improve their aerodynamic stability and reduce their noise emissions.

DLR's TRACE enables researchers to speed up the iteration cycle by testing shrouded propfan designs in simulations that supply data on how turbulence, speed, pressure and density affects an engine as it moves through a three-dimensional vector field. Recognized as one of the world's leading CFD applications for turbomachinery, TRACE employs high-resolution numerical schemes and multiprocessing technologies that enable it to use over 1000 processors simultaneously.

TRACE was developed to meet current and future needs of turbomachinery scientists but DLR's 4-year-old parallel computing platform was not, lacking the memory required to simulate state-of-the-art flow problems. As the system strained to support power-hungry TRACE calculations, scientists encountered more difficulties, and were wasting valuable time porting CFD data between development and deployment platforms.

DLR evaluated high-performance, scalable systems from several vendors. They were already using Sun SPARCstation™ workstations running the Solaris™ Operating Environment and Sun compilers including C++ and Fortran. Dr. Frank Eulitz, Head of Numerical Simulation at the DLR Institute of Propulsion Technology, had faithfully used Sun systems since his college days. "Sun systems offer stability, scalability and power-which are all interrelatedSSun systems are reliable and produced carefully. Their components are well made and easy to install."

Eulitz continued, "High-performance computer applications are as sensitive as high-performance race cars. We need a stable run-time environment to reliably support our CFD application. That way users do not have to worry about the platform. It's simply there. It's simply working..."

DLR chose Sun servers because of their stability, performance, scalability and portability. The first phase of DLR's Sun deployment involved the installation of a Sun Enterprise™ 4500 with eight processors and 8 GB of memory. This mid-range Sun server would support simulations that required no more than three to four days to process.

But DLR scientists needed to solve much more complex simulations-some that would require weeks of processing. In fact, researchers were facing problems that current high-performance computing (HPC) technologies could not even solve. The scientists faced a dilemma: they would always need servers with some of the highest performance levels available, but could they afford to continue purchasing the newest HPC technologies to remain competitive? Eulitz's team investigated other options, including a leasing agreement through debis-SfR (Solutions for Research).

debis-SfR, a joint venture between DLR and the Daimler-Chrysler-owned debis, enables German educational and research organizations to lease Sun Microsystems' HPC solutions. By leasing, DLR could have access to the most advanced computing technologies without the burden of outright purchase. The most powerful solution available through debis-SfR: a Sun Enterprise 10000 with 2 TB of storage and 64 processors would be perfect for running complex simulations.

debis-SfR ran a high-speed connection between its E10000 and DLR's facility 200 meters away, making the server appear as if it was in the next room. In less than one week, the scientists ported TRACE to the new server and ran a full propfan simulation that measured over 1 million mesh points per blade passage and generated over 80 GB of data-a simulation that was far too complex for the old platform. Over time, scientists found the E10000 to be five times faster than the old platform, even though both had the same number of processors.

Eulitz commented on the new Sun systems: "Suns offer great hardware and software reliability. They can start-up and run powerful applicationsSThey are clean performers." Eulitz continued, "System stability is so important in our environment. If you have a computer that is two times more powerful but just a little less reliable than another platform, it is important to go with the more reliable platform."

Along with increased performance and reliability, the Sun systems have also enabled seamless application and data portability-eliminating the overhead costs that used to arise when researchers moved data and applications. What's more, the new system has made it easier to integrate CFD data with results from interdisciplinary multi-physics simulation codes. Now scientists can merge the aerodynamic and structural results of various components to simulate how well they "fly" together.

As DLR scientists overcome challenges in their highly demanding field, they can focus on problems surrounding aerodynamics-not system downtime, shared data or ongoing system costs. Running sophisticated applications on high performance servers from Sun Microsystems' enables researchers everywhere to explore non-traditional ideas and deliver innovative designs - just like DLR does today.

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