20 Great Gifts for Engineers from $10 to $2 Million

by Barbara Shea on Nov 23, 2018 9:28:00 AM

Gifts for Engineers can usually be segmented into a few categories: Things you have to put together, science fiction, gaming, new technology, and witty phrases printed on stuff. A Google search of the term "Best Gifts for Engineers" will quickly validate this claim.

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.

Engine-Driven Compressor for Maintaining Aircraft Cabin Pressure

by Dan Hinch on Jul 11, 2018 12:27:47 PM

Commercial and military aircraft require that preset levels be maintained for aircraft cabin pressure, airflow, temperature, and humidity — regardless of flight altitude and aircraft speed. To satisfy these requirements, some amount of the airflow is typically removed from a bleed port located in a compressor section of the main engine, and the air pressure is adjusted to a preset level (through a pressure loss device) before it goes into the cabin. A better, and more effective, way to maintain the cabin environment over all of the aircraft’s operating conditions is to use a dedicated compressor driven by the main engine. Both the main-engine bleed system and the engine-driven compressor (EDC) need an environment control system to maintain cabin temperature and humidity.

Avoiding the "Bad Day" in Aerospace

by Francis A. Di Bella, P.E. on Jul 6, 2018 9:17:04 AM

The AS9100 Certification identifies companies who have qualified to manufacture products for the Aerospace Industry.  Manufacturers who meet the extensive requirements of the AS9100 Certification have committed to maintaining quality assurances that ensure that their products are engineered, manufactured and maintained to provide the aerospace customer with a quality product. 

Reverse-Brayton Cryocoolers

by Dimitri Deserranno on Apr 19, 2018 2:22:09 PM

Perhaps it is because Spring is so slow to come this year, but I have been thinking a lot about refrigeration and the different types of systems there are. Refrigeration systems that operate below 120 K are commonly referred to as cryocoolers. Figure 1 illustrates the most common usage of cryocoolers in the fields of superconductivity, liquefaction, and infrared sensors. As you can see, cryocoolers cover a wide range in temperatures, cooling loads, and applications.

Many gas turbines with radial compressors utilize a radial-to-axial inlet duct upstream of the first compressor stage. Aside from the fact that flow in the duct generates aerodynamic losses, the flow profiles at the duct exit, delivered to the inlet of the first impeller, also affects the performance of the compressor. 

Flow Coefficient and Work Coefficient Applications

by Mark R. Anderson on Mar 29, 2018 4:10:49 PM

In my last blog, I explored the concept of the flow and work coefficient.  In this blog, I will explore the practical application of the two parameters in machine selection and optimization. 

Flow Coefficient and Work Coefficient

by Mark R. Anderson on Mar 22, 2018 12:00:25 PM

Two often used quantities to characterize turbomachinery are flow coefficient and work coefficient.  The two are generally represented as Φ for flow coefficient and φ for work coefficient.  The mathematical definition for the two quantities are as follows:


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.

The Value of Visualizing Velocity Vectors

by Mark R. Anderson on Nov 9, 2017 11:12:39 AM

Beyond being a fun tongue twister, visualizing the velocity vectors is probably the most useful and intuitive information available in turbomachinery design. Many fundamental parameters can be gleaned directly from these triangles. These include: flow coefficient, work coefficient, stage reaction, de Haller number, diffusion factor, and diffusion ratio, to name just a few. A great many design rules are predicated on these parameters in the initial design process, which is generally geared to target velocities as the starting point, rather than a predetermined geometry.