Temperature envelopes in the turbomachinery industry are constantly increasing as the state of the art evolves in pursuit of better performance. This means engineers need to design compressors with higher and higher exit temperatures, and turbines and nozzles with continuously increasing inlet temperatures. This rise in temperature greatly impacts the selection criteria for materials used. 

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.

Flank Milling - How Hard Can It Be?

by Peter Klein on Jan 4, 2019 10:11:00 AM

 When designing compressors, engineers often use ruled-surface blades with the goal of making a shape that’s easily manufactured on a 5-axis machine.  Theses blades can be quickly machined in one pass by aligning the side of a cutting tool to the rulings. This process is often referred to as “flank milling.”  The alternative is to make many passes with the tool tip, a process known as “point milling”. For the right application, flank milling is often favored for shorter cutting times and better surface quality, but there are some caveats.

Reverse Engineering - Going from Part to Art

by Sharon Wight on Dec 7, 2018 9:12:37 AM

Have you ever needed to know the exact geometry of a compressor that has been running for years in your process plant? Perhaps you need to analyze how it would perform if the process fluid had to be changed to meet new government regulations. Or maybe there has been damage to the impeller and a complete mechanical analysis is required before a new one can be put into service. Eventually, everything, even well-designed turbomachinery, needs to be replaced or upgraded.

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.