SpinOffs

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!

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! 

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.

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.