Machine Type | Turbomachinery blog

Hello and welcome to the next edition in our introductory series to rotor dynamics analysis. In this installment, we’ll be looking at the specific purposes and objectives of performing rotor dynamics analyses; as well as the differences between lateral and torsional analysis. If you haven’t read the other entries in this series, you can find them here:

In earlier posts, we’ve established what the basic definitions and concepts are; shown the consequences of improperly performing rotor dynamics analyses; as well as what standards are in place to ensure these breakdowns and catastrophes are avoided. That raises the question, what exactly are we trying to do by performing rotor dynamics analyses?

We know based on our previous articles we are trying to determine the critical speed and in turn determine if further damping and other measures need to be taken to ensure that there is a proper separation margin between the operating speed of the machine and its critical speeds. But what will this accomplish? The answer is actually 3 answers!

We want to minimize and/or eliminate unplanned failures as much as possible, especially when these machines are counted on to keep planes in the air, the lights on, and in some cases, people alive! Have a look at this article from Halloween if you want an idea of what would happen if all our turbomachinery just stopped working.
Secondly, we want a low vibration level. In addition to providing comfort in the case of an aero engine or a car’s turbocharger, lower vibration levels ensures less undue wear and tear on expensive rotor train components.
Lastly, and this correlates with the others, ensure low maintenance requirements. Naturally the machine that can do its job the longest will be the one people desire, and rotor dynamics analyses play a large role when it comes to maximizing the service intervals for turbomachinery.

Overall, the purpose of rotor dynamics analyses, is to ensure maximize machine reliability in the interest of time, money, and most importantly, safety. Now let’s get into the differences between lateral and torsional rotor dynamics.

Rotor dynamics is typically split into two distinct kinds of analyses which are constantly brought up; lateral and torsional rotor dynamics. So, what is the difference between the two?

Vapor-Compression Refrigeration Systems

Posted Tuesday, January 28, 2020Tuesday, January 28, 2020 by Kimberley Squillante

Present day refrigeration is viewed as a necessity to keep our popsicles cold and our perishables fresh. But have you ever wondered what people did to keep their food from spoiling hundreds or even thousands of years ago? Or just what goes into a refrigerator system today? In this blog, we’ll take a look at how refrigeration works; the history behind it; and examine the cycle, working fluids, and components.

Schematic of Refridgeration System in AxSTREAM NET — Figure 1. Modern-day Refrigeration System in AxSTREAM NET

Introduction

Refrigeration is based on the two basic principles of evaporation and condensation. When liquid evaporates it absorbs heat and when liquid condenses, it releases heat. Once you have these principles in mind, understanding how a refrigerator works becomes much more digestible (pun intended). A modern-day refrigerator consists of components such as a condenser, compressor, evaporator and expansion valve, as well as a working fluid (refrigerant). The refrigerant is a liquid which as enters the expansion valve the rapid drop in pressure makes it expand, cool, and turn into a gas. As the refrigerant flows in the evaporator, it absorbs and removes heat from the surrounding. The compressor then compresses (as the name suggests) the fluid, raising its temperature and pressure. From here, the refrigerant flows through the condenser, releasing the heat into the air and cooling the gas back down to a liquid. Finally, the refrigerant enters the expansion valve and the cycle repeats. But what did we do before this technology was available to us?

Pump Performance Improvement Using AxSTREAM ION

Posted Tuesday, January 21, 2020Tuesday, January 21, 2020 by Suheab Thamizullah

As pumps have numerous uses, they constitute a significant part of energy consuming equipment. Therefore, pump efficiency plays a significant role in energy savings and operating cost. The design of a centrifugal pump is more challenging to reduce overall cost of the pump and increasing demand for higher performance.

Redesign Pump with Smooth Beta and Theta Distributions — Figure 1. Centrifugal Pump in AxSTREAM

There are two traditional approaches to design a pump for new requirements. One approach is to redesign or modify an existing impeller of centrifugal pump for increasing flow rate/head and efficiency. The modification will also involve selection of different geometric parameters and then optimizing them with the goal of performance improvement in terms of efficiency, increase the head, reduce cross flow and secondary incidence flows. The other approach is to design a pump from the preliminary stage to meet the desired design objectives. Most of the time, the designer knows what they need to achieve (performance target) but the challenge is in how to achieve this target within the given constraints (geometry, cost, manufacturability etc.).
Read More

Series on Micro Gas Turbines And How They Can Make the World Greener

Posted Tuesday, January 14, 2020Tuesday, May 26, 2020 by Daniel Green

Next Blog

If you’re familiar with turbomachinery, then you probably know the pivotal role they play in our lives. If you’re not, no biggie! Have a look at this blog where I discuss a world without turbomachinery. But where do microturbines fit in? I can’t speak for anyone else, but my mind immediately jumps to turbochargers in small-displacement car engines. There is, however, a whole slew of information, history, and applications for microturbines beyond being a component in your car.

The best place to start, is to establish just what a microturbine is and isn’t. Granted the prefix in the word is a dead giveaway, but just how small is a micro gas turbine? In terms of power output, a micro gas turbine puts out between 25 and 500 kW. The size of these machines varies; some systems can be the size of a refrigerator, while others can fit on your desk. For reference, some of these machines are smaller than your average corgi!

Micro Gas Turbine and Corgi — Figure 1: A micro gas turbine with a pencil for scale (left) and your average corgi (right). Not very aerodynamic, but awfully cute. Source

In terms of components, microturbines typically consist of a compressor, combustor, turbine, alternator, generator, and in most machines, a recuperator. While incorporating a recuperator into a microturbine system comes with its own set of challenges, the benefits are often well worth it as efficiency when recuperated hovers around 25-30% (with a waste heat recovery/cogeneration system, efficiency levels can reach up to 85% though).

Figure 3: A commercial airliner's turbofan engine the common image that is conjured when one thinks of turbines in transportation — Figure 3: A commercial airliner’s turbofan engine; the common image that is conjured when one thinks of turbines in transportation.

History

When and how did the concept of micro gas turbines come about? After the advent of the jet engine in World War II and the prominence of turbochargers being used on piston-driven propeller planes during the war, companies started to see where else gas turbine technology could be utilized. Starting in the 1950’s automotive companies attempted to offer scaled down gas turbines for use in personal cars, and you can read our blog covering that more in-depth here. You can probably guess by the number of gas turbine-powered cars on the road today, that it wasn’t very successful.

Fast forward to the 1970s, companies started to take an interest in micro turbines for stationary power generation on a small, portable scale. Allison developed microturbine-powered generators for the military that showed substantially lower fuel consumption in initial testing. In the 80’s, GRI supported the AES program where they attempted to develop a 50kW turbine for aviation applications, using a heat recovery system to improve efficiency through a cogeneration system. More recently, companies like Capstone have worked with GRI on new projects to introduce microturbines to different industries where they could be useful, using the latest advancements in technology to ensure higher efficiencies and reliability of designs past. To discuss the current state of affairs for microturbines however, it might be good to list some of their present advantages and drawbacks, and then explore where in the world they could be most useful.

Micro Turbine Compressor — Figure 4: A micro turbine compressor model.

Advantages and Disadvantages of Microturbines

As with just about any other type of technology, microturbines have their own set of advantages and disadvantages as a result of their design that are seen in their different applications.

Advantages:

– Lower emissions
– Lower noise level than comparable reciprocating engines
– Fewer moving parts with results in less maintenance needs
– Lower vibration levels
– Ligherweight, compact systems
– Diverse fuel selection (jet fuel, kerosene, diesel, natural gas)

Disadvantages:

– Very low efficiency without recuperator/waste heat recovery system
– High work requires high speeds (30-120 krpm) for small diameters
– Poor throttle response
– Expensive materials required for manufacturing
– More sensitive to adverse operating conditions

A Micro Gas Turbine — Figure 5: A Microturbine

Potential Transportation Industry Applications

There are a number of different industries which microturbines can be found both in and outside of the transportation. Throughout the upcoming months, we’ll be taking a closer look at:

– The Aviation Industry
– The Automotive Industry
– The Marine Industry
– The Rail Industry

Each of these industries has at least one application where micro gas turbine technology has the potential to conserve fuel and lower emissions without compromising power. In the next entry, we’ll look at the current state of the aerospace industry and where/how micro gas turbines can improve upon existing technology.

If you want to learn more about designing a micro gas turbine, or about the tools our engineers and thousands of others around the world rely on for their turbomachinery designs, reach out to us at info@softinway.com

Next Blog

Basic Definitions and Fundamental Concepts of Rotating Equipment Vibrations

Posted Tuesday, January 7, 2020Wednesday, July 15, 2020 by Daniel Green

Previous Blog Next Blog

Hello and welcome or welcome back to the January 2020 edition of our Rotor Dynamics Blog series! Here are the other entries in the series for those who are just joining us:

In our previous blogs we established that rotor dynamics is a branch of applied mechanics in mechanical engineering and is concerned with the behavior of all rotating equipment, but let’s have a closer look at some of the factors that affect the behavior of rotating equipment.

Here’s a non-exhaustive list of the different static and dynamic forces and phenomena that can act on a rotor train:

– Unbalance
– Gravity
– Bearing reaction
– Inertia
– Seals
– Fluid-rotor interaction
– Impeller aerodynamic loadings
– Misaligned couplings and bearings
– Rubbing between rotating and stationary components

As you can see there’s no shortage of different forces and factors which must be considered to ensure the smooth operation of your turbomachinery and other rotating equipment. While some of these factors are very familiar such as gravity, some factors like rotor unbalance have numerous causes. Here’s another (non-exhaustive) list of different factors that can cause rotor unbalance: Read More

Part Two: A Company Snapshot of 2019 – Looking Back and Looking Forward

Posted Thursday, January 2, 2020Thursday, January 2, 2020 by Daniel Green

Part 1

Software Upgrades:

2019 was a year of innovation and exploration for our engineering team as we worked with our customers to develop capabilities both in and outside the realm of turbomachinery. Our dedicated structural and rotor dynamics engineers worked with some of our AxSTREAM RotorDynamics customers to continually develop capabilities to perform torsional forced response analyses in reciprocating compressors. On the thermal-fluid modeling front, our engineers added capabilities to AxSTREAM NET, enabling it to be used for multiphase flows in heat exchangers, rocket engine nozzles, and refrigeration systems, as well as continued development of capabilities for analyzing secondary flows and leakages from turbomachinery flowpaths.

Rocket Nozzle Modeling in AxSTREAM NET (left) and CAD Model (right)

Perhaps one of the biggest buzzwords of the last decade (and for years to come!), SoftInWay’s engineers underwent a project to further streamline the turbomachinery design process leveraging Artificial intelligence (AI). While AxSTREAM ION™ had already made it possible to automate processes in AxSTREAM and enable interaction with external CAD/CAM programs and other commercial/in-house codes, AxSTREAM.AI™ takes it one step further. By utilizing machine learning to iterate designs continually and training the program to recognize feasible and infeasible designs, AxSTREAM.AI™ is able to develop components in just several hours, as opposed to month-long or year-long projects. Read More

A Company Snapshot of 2019 – Looking Back and Looking Forward

Posted Monday, December 30, 2019Thursday, January 2, 2020 by Daniel Green

Part 2

In what feels like the blink of an eye, 2019 has come to a close (well, almost). In the last decade, we have seen technology make leaps and bounds with advancements in everything from electric vehicles and propulsion, to artificial intelligence, to the microsatellite industry, and supercritical carbon dioxide (sCO2) power cycles. We’ve even seen the rise of the elusive and mysterious impossible burger. For engineers working in the field of technology as well as the SoftInWay team, it has been an exciting year full of new developments and growth; and we’d love to share a recap of our year with you, our readers!

So what has SoftInWay been up too this year?

Earlier in the year, we hosted a liquid rocket engine design/development seminar in Huntsville Alabama, AKA Rocket City USA. We had a good turnout from companies in the area that included Teledyne Brown, ATA Engineering, as well as other businesses large and small that call the Rocket City home. This event allowed us to show off our latest software development in the aerospace industry, AxSTREAM.SPACE, and how quickly and simply an engineer can design a turbopump for a liquid rocket engine as well as design/optimize the cooling channels in the engine’s nozzle, and perform the rotordynamics analyses for the turbopump.

Turbo Expo:

Thermal Management in Automotive Electric Propulsion Systems

Posted Tuesday, December 17, 2019Monday, December 30, 2019 by Suheab Thamizullah

There is a growing interest in electric and hybrid-electric vehicles propulsion system due to environmental concerns. Efforts are directed towards developing an improved propulsion system for electric and hybrid-electric vehicles (HEVs) for various applications in the automotive industry. The government authorities consider electric vehicles one of several current drive technologies that can be used to achieve the long-term sustainability goals of reducing emissions. Therefore, it is no longer a question of whether vehicles with electric technologies will prevail, but when will they become a part of everyday life on our streets. Electric vehicles (EVs) fall into two main categories: vehicles where an electric motor replaces an internal combustion engine (full-electric) and vehicles which feature an internal combustion engine (ICE) assisted by an electric motor (hybrid-electric or HEVs). All electric vehicles contain large, complex, rechargeable batteries, sometimes called traction batteries, to provide all or a portion of the vehicle’s propelling power.

EVs propulsion system offers several advantages compared to the conventional propulsion systems (petrol or diesel engines). EVs not only help reduce the environmental emissions but also help reduce the external noise, vibration, operating cost, fuel consumption while increasing safety levels, performance and efficiency of the overall propulsion system. However, there are many reasons why EVs and HEVs currently represent such a low share of today’s automotive market. For EVs, the most important factor is their shorter driving range, the lack of recharging infrastructure and recharging time, limited battery life, and a higher initial cost. Though HEVs feature a growing driving range, performance and comfort equivalent or better than internal combustion engine vehicles, their initial cost is higher and the lack of recharging infrastructure is a great barrier for their diffusion. Therefore, industry, government, and academia must strive to overcome the huge barriers that block EVs widespread use: battery energy and power density, battery weight and price, and battery recharging infrastructure. All major manufacturers in the automotive industry are working to overcome all these limitations in the near future.

Common Types of Electric Vehicles

Figure 1. Classification of EVs according to the types and combination of energy converters used (electric motor & ICE). SOURCE:**^[3]**

A more universal EVs classifications is carried out based on either the energy converter types used to propel the vehicles or the vehicles power and function [4]. When referring to the energy converter types, by far the most used EVs classification, two big classes are distinguished, as shown in Figure 1, namely: battery electric vehicles (BEVs), also named pure or full-electric vehicle, and hybrid-electric vehicles (HEVs). BEVs use batteries to store the energy that will be transformed into mechanical power by electric motors only, i.e., ICE is not present. In HEVs, propulsion is the result of the combined actions of electric motor and ICE. The different manners in which the hybridization can occur give rise to different architectures such as: series hybrid, parallel hybrid, and series-parallel hybrid. All these different EVs architectures are shown in Figure 2.

Figure 2. Architectures of different EVs and HEVs. SOURCE:**^[3]**

Oxygen Life Support Systems in a Spacecraft

Posted Tuesday, December 10, 2019Monday, December 30, 2019 by Yurii Hyrka