SpinOffs

   

Fluid Modeling: Liquified

by Mark R. Anderson on May 10, 2019 10:30:23 AM

Continuing on the topic from my previous blog, Getting Real – Advanced Real Gas Models, the counterpart to the perfect gas model for liquids is the “ideal liquid” model.  The ideal liquid model is very simple and is defined as:

 

            Density = constant

            Specific heat = constant

            Sonic velocity = constant

            Viscosity = constant…. or a simple temperature function

 

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. 

Simple Stall - Video Blog - Part 2

by Mark R. Anderson on Apr 12, 2019 9:33:58 AM

Our CTO, Mark Anderson, takes a fundamental look at simple stall and its impact on turbochargers stability and range. This is the second video in this 2-part series. Be sure to watch Part 1 first!

Performance Corrections for Compressor Maps

by Mark R. Anderson on Apr 9, 2019 9:56:09 AM

Turbomachinery performance is almost always analyzed and tested with a fixed inflow condition. In other words, the assumption is that the inflow fluid temperature and pressure is defined and unchanging over the map of machine performance. Since varying conditions often exist in practice, the performance maps are sometimes normalized, as shown in the figure below. The pressure ratio of a compressor is plotted versus a corrected mass flow range and rotational speed. 

Simple Stall - Video Blog - Part 1

by Mark R. Anderson on Apr 5, 2019 10:03:00 AM

Our CTO, Mark Anderson, takes a fundamental look at simple stall and its impact on turbochargers stability and range. This is the first video in this 2-part series. 

Water & Turbomachinery - Two Great Things, That Go Great Together

by Andrew Provo on Mar 22, 2019 10:17:34 AM

I work with water a lot here at Concepts NREC. Water is frequently the fluid that flows through various types of rotating equipment we design to either release or store energy. Mankind’s fascination with manipulating the movement of water goes way back; read Mark Anderson’s blog on  Early Water Handling to see just how far back it goes. Today, more advanced turbomachinery is used for both hydroelectric and hydrokinetic applications. 

What's Better than Perfect? Semi-Perfect Gas Models

by Mark R. Anderson on Mar 8, 2019 10:30:00 AM

In a previous blog, Fluid Phenomena Primer: Energy Versus Temperature, Specific HeatI explained the behavior for gas phase fluids and how the temperature is affected at high energy levels.  In another blog, When Perfect is Good Enough - Perfect Gas Models, we looked at the simple perfect gas model.  In this blog, we’ll explore the next step up in the hierarchy of gas thermodynamic modeling: semi-perfect gas.

Phase Change - Make Mine a Double!

by Mark R. Anderson on Feb 22, 2019 10:40:06 AM

As I’ve always said, there’s as much thermodynamics in a glass of beer, as there is in a power plant. Don't believe me? Read on. Phase change is common phenomena that we see all the time.  We’re most familiar with H2O, of course, in its various forms: ice, water, and steam. This is partly because it’s a very common substance (on Earth anyway) but also because it’s one of the rare fluid types that readily changes phase at temperatures and pressures humans can typically dwell in. 

 

Back to Beer...

When Perfect is Good Enough - Perfect Gas Models

by Mark R. Anderson on Feb 15, 2019 10:22:00 AM

What is a perfect gas?

A perfect gas is one that has a linear variation in energy with respect to temperature and a linear variation in pressure with respect to temperature at constant volume. The perfect gas model is the simplest of all models for gas phase fluids. For a perfect gas, we need only two unique properties of the substance to determine the relationships between pressure, density, energy, and temperature. 

 

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