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.

Beyond being a fun tongue twister, visualizing the velocity vectors is probably the most useful and intuitive information available in turbomachinery design. Many fundamental parameters can be gleaned directly from these triangles. These include: flow coefficient, work coefficient, stage reaction, de Haller number, diffusion factor, and diffusion ratio, to name just a few. A great many design rules are predicated on these parameters in the initial design process, which is generally geared to target velocities as the starting point, rather than a predetermined geometry.