SpinOffs

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.

Most turbomachines need to operate across a range of fluid flow rates and speeds. This is obvious in transportation applications where gas turbine engines and turbochargers need to operate at all of the speeds, altitudes and temperatures that the vehicles they power will encounter. In industrial and refrigeration applications, turbomachines need to have a wide operating range to make them appealing to end users who want efficiency under many operating conditions.

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.

Can you really get something for nearly nothing? In many cases, a properly-designed compressor casing treatment can extend compressor operating range without having to pay an appreciable efficiency penalty. Major automotive turbocharger OEMs have been leading this design effort for years and have successfully gained compressor operating range increase on both sides of the compressor (pressure versus flow) map. In most cases, the range increase has outweighed any efficiency penalty and best of all, these so-called “ported shroud” designs are naturally uncomplicated to implement, meaning that incremental cost is low.

Finding the root cause of a failure by narrowing down multiple overlaid symptoms can be a long and tedious process—and very often the true underlying problem is not what one might expect by a casual examination of the symptoms. That was the potential difficulty a customer of ours wanted to avoid when they investigated the catastrophic failure of a super-critical, feed-water pump used for a powerplant boiler.