Turbine components are placed right after the combustor and are therefore, subject to the highest temperatures in an engine. The turbine blades are directly in the line of fire (so to speak) of these incredibly high temperatures. Higher temperatures yield higher cycle efficiencies, meaning that the limit on efficiency for a cycle is determined by turbine materials. The current state of the art materials can only give so much heat resistance capacity, which makes blade cooling essential. In this post we’ll be taking a look at the various cooling methods that exist for turbine blades, and the tools to design them.
How important is cooling to the efficiency of gas turbine engines?
In a word, very. Let’s look at an example to better explain. Our fictitious engine without cooling has an overall pressure ratio of 40 where the maximum allowable turbine entry temperature (TET) is at 1498 K, yielding a thermal efficiency of 33%. When compared to a turbine with cooling, TET can be increased to 1850 K, yielding a thermal efficiency of 38%. This is an 8% increase in efficiency via the addition of cooling. In order to achieve good thermal efficiency in our cycles, turbine components must be cooled!
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 next entry in our series on micro gas turbines! If you’re new to this series, be sure to check out our earlier blog where we: introduce the concept of the micro gas turbine; look into the history of it; and discuss some advantages and disadvantages that come with this technology.
This time, we’ll be looking at micro gas turbines in the Aviation industry (if you couldn’t guess by the title). Believe it or not, the concept and configuration of a micro gas turbine has been present in this industry for decades. We’ll get into that in a minute.
Gas turbines are certainly no stranger to the aviation industry. As a matter of fact, when many of us hear the term “gas turbine” we immediately jump to the image of a jet engine powering a massive airliner carrying us to our next adventure.
Yes, these mighty turbines are indeed a staple in the aerospace industry. But did you know that micro gas turbines are also making a rise in this industry?
Although micro gas turbines first made an appearance as an alternative to traditional piston engines in the automotive industry, they have actually been present in the aviation industry for some time.
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
While we at SoftInWay are known for helpful articles about designing various machines and answering questions about the pros and cons of retrofitting your turbomachinery and powerplants, we believe it is important to also examine the lives of some of the men and women behind these great machines that do so much for the world.
The jet engine is one of the greatest inventions of the last 100 years. It has made transcontinental travel considerably shorter. A trip that might take days on a piston driven aircraft was cut down to hours thanks to the inception of the jet engine. To this day, millions of people rely on jet engines daily for everything from themselves for vacation travel to their packages for shipping goods overnight. These engines also give the U.S. military the ability to deploy to any part of the world within 18 hours.
But who invented the jet engine? This credit changes depending on who you ask. Some might answer it was Hans von Ohain. To others, this credit belongs to Sir Frank Whittle, OM, KBE, CB, FRS, FRAeS, RAF.
Why the discrepancy? von Ohain is known for creating the world’s first operational jet engine, and Whittle is credited with developing the turbojet earlier. While von Ohain’s first engine was the first to fly operationally in 1939, Sir Frank Whittle had been working on his design since the 1920’s. Today, we’d like to look at the life of Sir Frank Whittle, and how he created this world-changing machine. Read More
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?