There is No Such Thing as a Design Point

by Dr. Peter Weitzman on Oct 26, 2018 10:00:00 AM

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.

Extending the Operating Range of Centrifugal Compressors

by Adam Weaver on Sep 28, 2018 10:36:51 AM

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.

A Small Taste of Two Papers from Turbo Expo 2018 in Norway

by Barbara Shea on Jun 14, 2018 11:15:18 AM

The 2018 ASME Turbo Expo in Lillestrøm, Norway was, as always,  a smorgasbord of papers and presentations on the latest and greatest ideas in turbomachinery and gas turbines. Two of our favorites were from Mark R. Anderson and Felipe F. Favaretto, Concepts NREC employees. Coincidence? I think not. Felipe presented, “Development of a Meanline Model for Preliminary Design of Recirculating Casing Treatment In Turbocharger Compressors”:

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.

Off-Highway Turbochargers

by Dr. Nicholas C. Baines on Oct 20, 2017 9:57:27 AM

The turbocharger is a very mature device that has been refined over the past 100+ years to achieve the right compromise between competing requirements. Efficiency, boost pressure, and range are all important goals, but so are low inertia to combat turbo lag, and low cost for commercial success. For off-highway vehicles, durability and service life are also important. These vehicles often operate over extreme load cycles and in very dusty conditions. In some circumstances, foreign object damage and blade fatigue may be life-limiting for the turbocharger. Turbocharger manufacturers in this space have focused on getting the right balance of these factors rather than maximizing any single parameter, and designers know that further gains in one area come at a cost to the others.


What Next for Wider Flow Range Centrifugal Compressors?

by Dr. Colin Osborne on Sep 21, 2017 2:04:51 PM

Flow range is an essential consideration in the design of any centrifugal compressor system, regardless of the application. Adequate flow range is necessary, not only to assure that various off-design operating conditions are reachable, but that companion efficiency goals at off-design points are favorable. For many applications, these off-design points are located at the extremities of the compressor map (near choke or stall). In addition, it is not enough just to reach these off-design points; additional flow margin is needed to ensure surge control equipment can protect compressors from system surge events, including design uncertainties, manufacturing and assembly tolerances, as well as unexpected operating conditions.

Previous | Next