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.

Vibration and Resonance Issues in Turbomachines

by Arsalan Adil on Nov 29, 2017 3:09:18 PM

Structural vibration is a natural phenomenon exhibited by all structures, by virtue of simply possessing mass and having an associated structural stiffness. Thus, any structure or assembly of structures, with a mass attribution, will possess some structural stiffness. This stiffness will characterize the vibrational response of the structure, depending on the type of boundary conditions constraining the structure. For complex structural configurations, this vibrational response can be determined by numerical techniques, such as the finite element method, which allows calculation of the natural frequencies of vibration of the structure and the respective mode shapes of vibration associated with each of these natural frequencies.


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.

Turbomachinery Textbooks Focused on Engineering Design

by Barbara Shea on Jul 14, 2017 9:42:54 AM

The vast majority of turbomachinery textbooks emphasize analysis when the heart of engineering is based in design. Concepts NREC is uniquely qualified to share the nature and process of engineering design. When Concepts NREC decided to write and publish a range of turbomachinery textbooks, the objective was to emphasize engineering design rather than analysis.  

New engine development is a costly endeavor and making the right decisions early in the engine design is extremely important. It requires multi-disciplinary consideration of the engine thermodynamic cycle coupled with preliminary aerodynamic design of key engine components. This includes evaluation of size, weight and cost parameters, with constraints imposed by aero, structural, geometrical, manufacturing, and material requirements.

Multidisciplinary Optimization of Turbocharger Turbine with Non-Radial Blades for Two Operating Points

by Dr. Nicholas C. Baines and Oleg Dubitsky on May 25, 2017 6:02:28 PM

The turbine of an automotive turbocharger is subject to a wide and demanding range of requirements and constraints. High efficiency is required to reduce the pumping work of the engine that can make a small but desirable improvement in fuel economy. The automotive application also requires a good transient response, and a low rotating inertia of the turbine is necessary for this. Durability and the ability to operate for a guaranteed lifetime are required – but such performance is not easy to achieve, given the hot gas environment and the way the turbine is subject to frequent changes in condition. The market is very competitive, and so manufacturing cost is very important. These various factors are in competition with each other, and a successful turbine is one that achieves the right balance between them, rather than one that excels in one particular area.

Turbocharger Market – Is There Room for Growth?

by Dr. Nicholas C. Baines on Apr 20, 2017 1:19:51 PM

The recent announcement that Bosch Mahle Turbosystems is up for sale demonstrates just how difficult it is to succeed in the mainstream turbo market that is already served by very well established OEMs. It’s hard to see that they did anything wrong. They were funded by two very large companies, they had a very large lead customer, a realistic timescale to profitability, and an early presence in China.

Topics: Turbochargers