SpinOffs

   

Entropy Happens… Deal with It!

by Francis A. Di Bella, P.E. on Jul 19, 2019 9:09:00 AM

If there’s one thing good about sitting in snarled traffic in Boston, it’s that you get to see some very original bumper stickers. The most recent bumper sticker I saw was probably the strangest one, no doubt created by some engineering professor who doesn’t see that the glass is half full, but that it has a safety factor of 2! Nevertheless, the bumper sticker stated the obvious when one thinks about it: ENTROPY HAPPENS! And then, to emphasize the point, the artist has the letters slowly “evaporating,” demonstrating graphically that entropy proceeds from order to chaos.

In Thermodynamics: “What Goes Around-Comes Around” is a Good Thing

by Francis A. Di Bella, P.E. on Jun 28, 2019 10:07:50 AM

When discussing the efficiency of transforming one form of energy to another, circularity is the way to go. Anyone who has spent even a little time studying engineering thermodynamics knows that the continuous transformation of energy from a heat energy source to produce mechanical or electrical power must contend with components that operate in a cycle. The key word here being “continuous”. The combustion of any carbon-hydrogen bond material (i.e., fossil fuels), or the liberation of heat energy from any number of materials when placed in a piston-cylinder, would not be very useful if the piston is not returned to its initial “precombustion” position. It is literally the difference between the one-time launching of an object from the cylinder or the continuous production of rotary shaft power; power that can be used to propel a vehicle forward or turn an electric generator. It is the cyclic operation of the fluid in the thermodynamic cycle that enables heat engines and refrigeration cycles to provide continuous power, or cooling, that is needed for the safety, security, comfort and all the other “hierarchy of needs” that was so well formulated by the renowned humanist psychologist, Dr. Abraham Maslow.

The Tesla Turbine – A Solution Looking for the Right Problem

by Barbara Shea on May 17, 2019 8:20:44 AM

The great engineer, Dr. Nikola Tesla, is best known for his work with alternating current (AC) electricity, but, did you know that he patented a bladeless type of turbomachinery in 1913? Called the Tesla Turbine, he developed it while trying to make an engine that was light enough to power his ultimate goal of building a “flying machine”. Tesla-type turbines can also be referred to as multiple-disk, friction, shear-force, or boundary layer turbomachinery.

Getting Real – Advanced Real Gas Models

by Mark R. Anderson on May 3, 2019 10:28:59 AM

The Refprop program

The calculations in the National Institute of Standards and Technology (NIST) Refprop program are generally considered the most accurate thermo-fluid models available.  The routines are widely used in many applications. 

 

The models

Several different models are embedded in the Refprop formulation. The most important are the  Benedict-Webb-Rubin equations of state for the pressure-temperature-density relationship. 

Going Through a Phase – Modeling Phase Change with Cubics

by Mark R. Anderson on Apr 26, 2019 9:32:08 AM

When fluids undergo a phase change (see Phase Change - Make Mine a Double), it typically has a very significant effect of the flow behavior and energy level of the system.  Some examples of this are: cavitation in a pump, condensing near the exit of a steam turbine, even the everyday phenomenon of the weather is basically a never-ending phase change process of water, and its interaction with air. 

Specific Speed Demystified

by Mark R. Anderson on Jan 11, 2019 9:40:00 AM

In my blog Flow Coefficient and Work Coefficient, I outlined the basic concept behind the flow and work coefficient. These nondimensional parameters are widely used to characterize axial and radial turbomachinery. Another widely used parameter for radial design is “specific speed”. For something with such a finite name, specific speed is perhaps the most mysterious and non-intuitive parameter in all of turbomachinery. In this blog, I'll lay the ground work for understanding specific speed.

Top Five Coolest Turbomachinery Applications

by Barbara Shea on Oct 4, 2018 4:21:33 PM

Most people have no idea what turbomachinery is, but some of the coolest things on (or off) this planet involve turbomachines.  Here are my picks for the top 5. 

Designing Turbomachinery is like Solving a Rubik's Cube

by Barbara Shea on Sep 21, 2018 10:01:00 AM

I think we can all agree that designing turbomachinery is hard. There are just so many moving parts (pun intended) in the design process, and they are all interconnected.  When you change the blade shape, it changes the aerodynamics, and could impact manufacturability. Everything you change has a cascading effect across many different areas, because all of the areas are linked; just like a Rubik's® cube! Only, in turbomachinery design, you are not always trying to get all of the sides to be one color. Heck, even a 3-year old can do that

Early Water Handling

by Mark R. Anderson on Aug 24, 2018 8:17:20 AM

I am fascinated by ancient cultures. After my recent visits to Roman ruins in Central Europe (see  A Turbomachinery Engineer's Summer Vacation), I began to wonder how far back mankind’s mastery of air and water handling actually went.  Turns out, quite far. So far, in fact, that it goes back to the very origins of civilization, and was perhaps, even a necessary precursor of civilization.

The Slip Factor Model for Axial, Radial, and Mixed-Flow Impellers

by Mark Anderson and Chanaka Mallikarachchi on Jul 20, 2018 10:00:25 AM

Ideally, the exit flow angle for an impeller should be the same as the exit blade metal angle. However, the exit flow angle deviates from the blade guidance at the impeller exit due to the finite number of blades. Correctly predicting flow deviation is a critical task in meanline and through-flow modeling because the exit flow angle is directly related to the work input and the pressure rise across the impeller.

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