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Hello and welcome to the latest revolution in our series on rotor dynamics and bearing analysis. This month, we’ll be looking at the importance and procedure of modeling the bearings and structural supports in a rotortrain. If you haven’t had a look at the other entries in this series, you can find them here: Series Preface
So let’s get started, one of the first things a rotor bearing system needs aside from a rotor, is, well, bearings! But what are bearings? I’m glad you asked!
Bearings are mechanical components used to restrict the motion of the machine and support the load while protecting other elements by reducing friction between moving parts. In fact, you might even say it bears the loads (axial and/or radial) caused by a rotor.
Bearings come in different materials, shapes and styles depending on their application, and can be found in everything from turbomachinery to reciprocating engines to things like hard drives and even fidget spinners. But what are the bearings commonly encountered in turbomachinery, and what effects can they have on the machines they are used in? Read More
Hello! Welcome to this edition of our series on micro turbines! Today we’ll be covering micro turbines and the roles they play in the automotive world.
“Big wheels keep on turnin’…”
Now here’s the real question, when you see that lyric which song do you think of first? Having gotten that stuck in everyone’s head, let’s get on with today’s topic: micro turbines in cars.
I mentioned in the intro to the series that when I think of micro turbines my mind immediately jumps to turbochargers like those used in reciprocating engines seen in cars, trucks, boats, and small airplanes.
They are, in essence, the same, but also different. For example, a turbocharger uses exhaust gas from a reciprocating engine to drive a compressor to pull more air into the engine, while a micro turbine drives a compressor to pull air into a combustor and then also drives a generator to create electric power.
The Achilles heel of turbochargers has always been the time between pressing your foot to the gas pedal and waiting for the engine to respond with the desired power. This lapse in engine response, commonly termed turbo lag, is what has hindered turbochargers from delivering optimal performance. The aim of a turbocharger is to provide more power, better efficiency and less lag in power delivery. Engine efficiency is becoming more important than ever before, leading to the development of smaller engines. However, the power requirements are not decreasing which means the loss in engine displacement from small designs must be picked up with alternative technologies, such as turbochargers, which can help improve power delivery and fuel economy.
Electric turbochargers (e-turbos) provide a solution to eliminating turbo lag while adding additional performance benefits. This allows for larger turbocharger designs which can provide larger power and efficiency gains, stay cooler over longer periods of use, and drastically improve engine responsiveness. Garrett Motion are developing e-turbos for mass market passenger vehicles set for launch in 2021, with a claimed fuel efficiency improvement of up to 10%. When used on diesel engines, this e-turbo could be up to a 20% reduction in NOx emissions. In most cases, fuel efficiency will be improved by about 2 – 4%. Other manufacturers such as Mitsubishi and BorgWarner are already developing their own electric turbos and are expected to have announcements in the near future matching the trend in e-turbo development.
Hello and welcome to the latest revolution in our series on rotor dynamics and bearing analysis. This month, we’ll be looking at what steps need to be taken to accurately model a rotor train, from the components on the rotors themselves to the bearings and structural components that support the entire machine. If you haven’t had a look at the other entries in this series, you can find them here: Series Preface
So what is the importance of accurately modeling a rotor-bearing system? Well we already know that an inaccurate analysis can have catastrophic consequences… If you want to know more about why, I also suggest looking at entry 2, titled “Why is Rotor Dynamics so Important?”.
Steam turbines account for more than half of the world’s electricity production in power plants around the world and will continue to be the dominant force in electricity power generation for the foreseeable future. The enhancement of steam turbine efficiency is increasingly important as the urgency to reduce CO2 emissions into the atmosphere is a problem at the forefront of power production. Increasing efficiency in steam turbines, and other components of power plants, will help meet the growing demands for electricity worldwide while reducing harmful greenhouse emissions.
Steam turbines are used in coal-fired, nuclear, geothermal, natural gas-fired, and solar thermal power plants. Also steam turbines are increasingly needed to stabilize fluctuating power demands from solar and wind power stations as renewable energy sources grow worldwide. The current emphasis on steam turbine development is for increasing efficiency, mainly by increasing steam turbine capacity, as well as increasing operational availability, which translates to rapid start up and shut down procedures. Read More
I was sitting in a meeting with a customer this morning, and a thought kept running through my head: why aren’t more people outsourcing work to computer programs in our industry?
The turbomachinery industry has no shortage of brilliant PhD-level engineers who have a million correct reasons to explain why solving complex flow issues is so complicated; but have they considered how utilizing artificial intelligence may be able to lighten the load?
Our task this morning was to help a customer who is developing an innovative piece of turbomachinery for waste heat recovery as well as their end-customer who will have the pilot machine installed. Our role during the call felt akin to the role of an application engineer; meaning that we did not have to do a complex design on the fly. Instead we answered complex questions about a set of data which we know and have pre-calculated.
It seems that opportunities for leveraging Artificial Intelligence are all around us and are becoming mainstream, but are not as widely used in our industry as if feel they could be, and still seen as an R&D pipe dream rather than a commercial and business engine.
It has been about a year since we at SoftInWay started seriously developing and using our AI engine AxSTREAM.AI; it was driven by 3 needs:
1. With a size of 85-90 people and a customer rate growing at about 20-30% a year, how can we offer increasingly better engineering services faster, without sacrificing quality or cost-effectiveness?
2. How can we support the Sales team properly in preparing proposals and engineering concepts without having to use un-billable engineering time?
3. How do we help our external customers who have “one-off" projects to complete them efficiently and NOT have to pay for permanent in-house employee or external consultant rates to do work.
Coming from math/finance background the answer was always simple in my mind: train an AI program to do the work so that our team is maximizing their time thinking about new ideas, and everything that was done before in design and application engineering can be in one way or another reflected in a training network or methodology.
I feel that this can be helpful to large companies trying to capitalize of years of historical experience and counter the losses of workforce turnover due to age, as well as startups that don’t have the budget to hire a full engineering team, or the internal skillset to do all of the work.
Do you agree or disagree?
If this sounds like a familiar problem to you, it might be time to consider “hiring” AxSTREAM.AI to tackle your project before things get “supercritical”. Let me know via private message or email: Valentine@softinway.com
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?
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.
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?
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.
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
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!
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).
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.
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.
– 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)
– 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
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 firstname.lastname@example.org