SpinOffs

Valentine’s Day is February 14, and while some cynics refer to it as a “Hallmark holiday”, most people commemorate the day in some way. One of the biggest challenges is finding a card that perfectly captures the way you feel about someone, while also reflecting who you are.  Well, Concepts NREC has created some turbomachinery-themed Valentine’s Day cards for engineers. These fall into the Art end of our Art-to-Part Solution.

Temperature envelopes in the turbomachinery industry are constantly increasing as the state of the art evolves in pursuit of better performance. This means engineers need to design compressors with higher and higher exit temperatures, and turbines and nozzles with continuously increasing inlet temperatures. This rise in temperature greatly impacts the selection criteria for materials used. 

 When designing compressors, engineers often use ruled-surface blades with the goal of making a shape that’s easily manufactured on a 5-axis machine.  Theses blades can be quickly machined in one pass by aligning the side of a cutting tool to the rulings. This process is often referred to as “flank milling.”  The alternative is to make many passes with the tool tip, a process known as “point milling”. For the right application, flank milling is often favored for shorter cutting times and better surface quality, but there are some caveats.

Have you ever needed to know the exact geometry of a compressor that has been running for years in your process plant? Perhaps you need to analyze how it would perform if the process fluid had to be changed to meet new government regulations. Or maybe there has been damage to the impeller and a complete mechanical analysis is required before a new one can be put into service. Eventually, everything, even well-designed turbomachinery, needs to be replaced or upgraded.

Below is a 4 minute video blog from Mark Anderson, Concepts NREC's Chief Technology Officer, on the geometry of radial compressors. In it, he details the various parts of the compressor wheel, including the inducer, splitters, backsweep, etc. He also looks at open and closed (shrouded) impellers and the pros and cons of each design.

Click on the image below to launch the full-size video.

As an engineer in the rotating machinery world, it is my job to design things that work for a very long time. To help ensure this, we have evolved the best analytical tools to calculate the stresses and deflection of the parts we have so carefully designed. But sometimes, we lose track of what matters. We know that material strength, weight, stiffness, toughness, thermal conductivity and thermal growth all matter. They are in a material database, so they must.

Below is 3 minute video blog from Mark Anderson, Concepts NREC's Chief Technology Officer, on splitter design for radial compressors. Click on the small thumbnail image below to launch the full-size video.

Extending the operating range of centrifugal compressors has been a highly sought-after goal for several decades. In fact, the potential benefits have motivated researchers to develop and put into practice many pieces of technology, including full span inlet guide vanes (IGV’s), complex multistage systems with interstage bleed, passive casing treatment, and many others.

In the mid 1980’s, while serving in the Canadian Air Force, I had the good fortune, on one of my many adventures, to fly into Sondrestrom Air Base in Greenland. The Base is at the head of a beautiful fjord, so the scenery during the flight to Sondrestrom was magnificent. We arrived in the early summer on a beautiful clear day. I got out of the plane and wandered around the base while the aircraft was being serviced. One feature that caught my eye was all of the bright yellow ropes and stanchions that were strung from building to building. I couldn’t figure out what they were for, so I stopped one of the locals and asked, “Why the Yellow Ropes?”  Now, for those who are not students of the geography of Greenland, Sondrestrom is north of the Arctic Circle, and, apparently, the weather is not always as bright and clear as it was that day! As a matter of fact, one of the meteorological phenomena in the area was virtually instantaneous whiteouts, caused by snowstorms funneling up the fjord. Several people had been caught out between buildings and become disoriented during a blinding storm, a dangerous thing during the long darkness of winter. To eliminate this danger, they had put up the yellow ropes to safely guide people to their destination.

Computational fluid dynamic analysis (CFD) has become a standard part of the turbomachinery design process. Within Concepts NREC’s Agile Engineering Design System, FINE/Turbo, from our Partner NUMECA International, is the tool used to accomplish aerodynamic analysis of designs by applying standard methods of three-dimensional analysis. However, arriving at a converged CFD solution in any CFD program can sometimes be a challenge.