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.


Full Disclosure on Non-Disclosure Agreements

by Bradley C. Leiser on Oct 13, 2017 9:41:21 AM

If you are working in a technical field as an engineer, and odds are you do, if you are reading this blog, then you have almost certainly come across a few Non-Disclosure Agreements (NDAs). You have probably been asked to sign one or have asked someone to sign one. NDAs are not, by any means, restricted to the technical world, but their close tie to patents and patent applications make them very commonplace in our field of turbomachinery. In this blog, I’ll briefly dissect the anatomy of NDAs, explain their dual purpose, and share a few pitfalls to watch out for as well.

Turbomachinery in Fire Fighting

by Mark R. Anderson on Oct 5, 2017 10:26:26 AM

I was a firefighter (we never call ourselves firemen) for more than ten years.  While this was only a part time, volunteer gig, I was a turbomachinery developer and modeler as my full-time job.  Obviously, firefighters use all kinds of turbomachinery and I found it interesting to experience it from the user’s perspective.

We Are All Being Robbed!  Some Thoughts on Energy Heat Recovery

by Francis A. Di Bella, P.E. on Sep 27, 2017 10:12:54 PM

There are not many people who would argue that if you only received 30% of a commodity that you need to purchase every day to enable you to have your share of “…life, liberty and the pursuit of happiness”, then you should have some recourse to get the rest of your order or some money back. However, each day, everyone in the United States and throughout the world purchases energy. The availability of a ready source of affordable energy is one of the criteria for a country’s industrial economy and the prosperity of its citizens. Every engineer learns very quickly that not all the energy you pay for can be transformed into useful form. The engine in the transport vehicle that brings you to work is likely to have an efficiency as low as 25%. The hot water for the lavatories in your office building has been heated with a much more respectable efficiency of 80-90%, at least according to the First Law of Thermodynamics.  However, if your office building is heating water to only 105-110°F, using a fossil fuel-fired furnace, then the Second Law of Thermodynamics can be used to determine the second law efficiency to be only 15%. In contemporary engineering thermodynamics terms, you’ve increased the entropy of the universe. In contemporary layman’s terms, you’ve been robbed!

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.

Bearing selection is an interesting concept. Can you really select the bearing – or does the bearing select you? It seems that we have come to understand where to use bearings by where they have been used successfully in the past. For instance, we’ve come to know the turbocharger bearing is a floating ring bearing, foil bearings are on the aircraft air-cycle machines, and the standard bearing for midrange industrial pumps is the preloaded pair of ball bearings in the back and a deep groove bearing up front.  We also know that the big industrial compressors and turbines use tilt pads, canned pumps and mag drives use carbon and ceramic sleeves, and if you look far enough back, you might find a whole family of machines using bronze sleeves with pick-up rings. Those old sleeves got us through the industrial revolution. Recently, I saw a vendor with a bearing offering that has a wet sump under the bearing and they use the thrust collar to pump oil up into the sleeves. What was old is new again, but better! 

Where Does CAD fit in the CAE Process for Turbomachinery?

by Dr. Peter Weitzman on Sep 7, 2017 12:19:33 PM

A common struggle for mechanical engineers using Computer Aided Engineering (CAE) tools is the time-consuming process of moving geometry between the CAE system and Computer Aided Design (CAD) software. This blog will explore ways to reduce time spent on this process.

Protecting New Ideas: Navigating the Corporate IP Landscape of Today

by Bradley C. Leiser on Sep 1, 2017 8:19:54 AM

An engineer named Victor makes a few final adjustments to his novel radial compressor design just before midnight.  With a deep breath, he clicks the “Save” button and pushes back from his desk. He has done it, he has brought to life something new.  He feels a little like Dr. Frankenstein and shouts out – “It’s alive!” to the empty office.

Measuring Aerodynamic Blockage

by Mark R. Anderson on Aug 23, 2017 3:54:27 PM

Aerodynamic blockage is a comparatively simple parameter to measure and reveals important aerodynamic performance data. Aerodynamic blockage is directly related to the displacement thickness concept of boundary layers. It represents the fraction by which a flow passage is effectively “blocked” by the presence of the low momentum boundary layer regions. If an analyst knows the aerodynamic blockage, the boundary layer displacement thickness can be directly computed, and vice versa, if the boundary layers are uniform across the passage cross section.

When and Why You Should Hire an Expert

by Barbara Shea on Aug 17, 2017 4:30:08 PM

Every company in the turbomachinery industry needs robust technical expertise to survive in this very mature business. Whether you make a rotating component or use one in a product, your in-house engineers have to consider many factors when designing a product. They must find the appropriate balance between the competing factors of higher efficiency, lower cost, ease of manufacturability and increased performance. Doing this task well requires insight across many disciplines. It also requires a deep understanding of the impact the various trade-offs made on the product and your bottom line.

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