The History of Turbochargers, Part 2

Hello! And welcome back for part 2 of our series on “A Brief History of the Turbocharger”. To read part 1, which compares superchargers and turbochargers, and explains the early history of turbochargers and forced induction from the turn of the century through to World War 1, click here. Having covered all of that, let’s pick up from where we left off!

Following World War 1, and the work of Dr. Sanford Alexander Moss, Alfred Büchi, who had created the first true turbocharger, had continued innovating following the failure of his first design. By 1925, he had a working turbocharger design that consistently and reliably worked (1).

Following this breakthrough, the turbocharger saw its first commercial application on ten-cylinder diesel engines. Since diesel engines are typically built to withstand the high-pressures required by their operating conditions, the pressures generated by using forced induction are easily accommodated. As a result of adding the turbochargers, the engines upped their horsepower ratings from 1750HP, all the way to a whopping 2,500HP. (1)

The Hansestadt Danzig, one of the German ships fitted with the 10 cylinder turbodiesel engine described above
The Hansestadt Danzig, one of the German ships fitted with the 10 cylinder turbodiesel engine described above. (shipspotting.com)

For Büchi, this was a great achievement, as it marked the first commercial application of a machine that he had first begun working with more than 20 years prior. For the turbocharger, however, this was just the beginning. Read More

Active Magnetic Bearings – When Magic Serves Engineers

From the beginning of the turbomachinery era, in the 19th century, engineers have been thinking about ways to reduce losses in rotating machines. Losses connected with fluid motion or producing the useful effects are related to the main purpose of machine operation,while losses in rotor bearings are just annoying and inevitable. Fluid film and rolling element bearings are effective solutions, but their operational principles cause increased friction – the best predictor of losses. But what if we could reduce the losses in rotating machines by avoiding the friction in required supports? What if a rotor could levitate and rotate in the air held by some magic forces? And furthermore, what if this magic could give us even bigger dividends, for example, enabling variable stiffness of rotor supports and safe passing through resonances? Luckily, engineers have already invented how to turn this magic into reality with active magnetic bearings.

The early patents of active magnetic bearings principles were recorded during the World War II, but the decisive breakthrough in production and applications of them were made during the the last three decades when the latest research about the active magnetic bearing operation and control made utilization feasible and economically viable [1].

The early patents of active magnetic bearings principles were recorded during the World War II, but the decisive breakthrough in production and applications of them were made during the the last three decades when the latest research about the active magnetic bearing operation and control made utilization feasible and economically viable [1].

Active Magnetic Bearing and its Components
Active Magnetic Bearing and its Components [2]
The main idea of an active magnetic bearing is based on the electromagnetic processes. Electrical current passing through densely wound copper coils creates magnetic fields which interact with a magnetized sleeve connected to the rotor.

Sounds pretty simple, right? But why on Earth did it take so much time to go from the general ideas to a real industrial application of active magnetic bearings? Read More

Anti-Icing Systems in Airplanes: Boeing 737-300/400/500

Update – March 1, 2023: AxSTREAM NET is our legacy software depreciated by AxSTREAM System Simulation. System Simulation was born out of the union of the legacy AxCYCLE and AxSTREAM NET software packages.

Through the decades, the aircraft industry always improved their onboard systems to get the best performances, security and comfort. In order to build a lasting travel type, security of the aircraft is one of the main goals for engineers. Due to rough exterior conditions while flying, especially at high altitude, with relative humidity and very low temperatures, the freezing temperature can cause the plane to ice. Ice can have major impacts on the aircraft’s weight and aerodynamical phenomena, – especially the lift – (the lift can decrease to 40% due to ice). Modeling and installing a specific system to prevent ice is a necessity. Therefore, aircraft designers developed an anti-icing system inside the wing to prevent ice.

There are several anti-icing systems on aircraft, mostly depending of the engine’s type. Most of aircrafts use the bleed air system, which consists of using a hot bleed air to warm up the wing leading edge. Another system named de-icing boots system is mostly used on turboprop aircrafts and consists of black rubbers at locations prone to icing which inflate and literally break the ice. Another system is simply an electrical leading edge warm up directly installed in the wing leading edge. Those examples are just an introduction to some anti-icing systems that aircraft industry has develop and are using. Each have pros and cons.

Here, we will focus on the anti-icing system using hot bleed air. This approach is used by the Boeing 737-300/400/500 anti-icing system with hot bleed air warming the leading edges.

Typically, this type of anti-icing system consists of a hot bleed air flow provided by the engine compressor’s stages to warm up the plane’s wing leading edge. The wing anti-icing system is made of two independent pneumatic systems among others, providing hot bleed air from each of the two turbofans separately. The hot bleed air is ducted via the engine bleed valve from the fifth compressor stage. If the pressure isn’t enough, bleed from the ninth compressor stage can additionally be used. Note that the fifth stage bleed air temperature is approximately 340°C and the ninth stage one is approximately 540°C which are too hot to be used in aircraft’s pneumatic systems such as hydraulic pressurization or potable water system pressurization for example. The hot air then runs through a pre-cooler to reduce the temperature to 200°C and this cooled air is distributed via the bleed ducts to consumers like the air conditioning packs for example and the wing anti-icing system. In order to know the moment to use the anti-icing system, the aircraft’s pilots use the visual ice indicator which is situated in the middle beam of the window. Once the probe is icing, the pilots enable the anti-icing system. Hence, hot bleed air is provided to the slates number three, four and five as shown in Figure 1.

Landing Edge Slats
Figure 1 – Leading Edge Slats

Due to the larger diameter and the aerodynamics phenomena, slates number one and two do not need any anti-icing devices. Once the anti-icing system is enabled, the hot bleed air is guided along telescopic pipes then is distributed via piccolo tubes as shown in Figure 2. From there, it exits the piccolo tubes through little holes, warms the wing leading edge and flows out of the wing through exit holes situating on the wing’s lower surface. Read More

Centrifugal Compressors for Fuel Cells

Update – March 1, 2023: AxSTREAM NET is our legacy software depreciated by AxSTREAM System Simulation. System Simulation was born out of the union of the legacy AxCYCLE and AxSTREAM NET software packages.

The development of fuel cell technologies and improvements in fuel cells power densities combine to make the use of fuel cells possible in different power sectors as primary or secondary power sources for commercial purpose, residential power requirements, and automobiles, etc. The fuel cell harnesses the chemical energy of a fuel along with an oxidizing agent by converting it into electrical energy through a pair of reactions. For example, in a hydrogen fuel cell, as shown in Figure 1, the hydrogen combines with oxygen from the air to produce electricity and releases water.

Fuel Cell System
Figure 1 Fuel Cell System [1]
The design of a fuel cell system is quite complex and depends on fuel cell types and their applications. With so many possible combinations of fuel cells, this article will not focus on different type of fuel cells, but on Air Management Systems which may significantly affect the overall performance of a fuel cell system.

Air Management Systems

Key sub-systems of any fuel cell system are the fuel processor, fuel cell stack, air management and power management systems. The air management system strongly affects the fuel cell stack efficiency and the power loss of the fuel cells. Therefore, it is necessary to develop a clean, reliable, cost-effective oil-free air system [2].

Major tasks in air management system are Air Supply, Air Cleaning, Pressurization and Humidification.
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Introduction to Performing Torsional Rotor Dynamics Analysis

Previous Blog 

Hello and welcome to the last part of our series on Rotor Dynamics! In today’s blog we’ll be concluding with torsional analysis, and the steps needed to perform this type of analysis. If you haven’t had a look at the other entries in this series, you can find them here:

Series Preface

  1. What is Rotor Dynamics? And Where is it Found?
  2. Why is Rotor Dynamics so Important?
  3. What API Standards Govern Rotor Dynamics Analysis?
  4. Basic Definitions and Fundamental Concepts of Rotating Equipment Vibrations
  5. The Purposes and Objectives of Rotor Dynamics Analyses
  6. The Importance of Accurately Modeling a Rotor-Bearing System­
  7. Modeling Bearings and Support Structures in a Rotor Bearing System
  8. Introduction to Performing Lateral Rotor Dynamics Analysis

 

In an earlier blog, we covered the basic definitions of lateral and torsional analysis. Lateral analysis is concerned with the bending behavior of a rotor train. Torque is a measurement of force that causes an object to rotate on an axis such as when a component needs to be “torqued to spec” in a car’s engine, for example. Torsional analysis, meanwhile, looks at the twisting behavior of the rotor train.

In the context of rotor dynamics, torsional vibrations refer to the oscillatory torsional deformations encountered by the shafts in the rotor train.

Pictured - A shaft undergoing torsional vibration
Pictured: A shaft undergoing torsional vibration.

If these torsional vibrations and excitations are left undamped and aren’t analyzed properly, breakages and catastrophic failures can occur similar to undamped lateral excitations. For more on that, you can read up on the importance of rotor dynamics analysis here.

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A Brief History of the Turbocharger – Part 1

Turbochargers are one of the more common turbomachines out there today! As everyone is making efforts to lower carbon dioxide emissions in automobiles, and the automotive OEMs engage in a “horsepower war”, the turbocharger will likely continue to grow in popularity for both civil and commercial uses.

But how did these machines get so popular? That’s what we’ll be exploring in this blog miniseries! Today’s blog will introduce the concept of the turbocharger, and the beginnings of its development around the turn of the 20th century.

Turbocharging engines and the idea of forced induction on internal combustion engines are as old as the engines themselves. Their intertwined history can be traced back to the 1880’s, when Gottlieb Daimler was tinkering with the idea of forced induction on a “grandfather clock” engine. Daimler was supposedly the first to apply the principles of supercharging an engine in 1900, when he mounted a roots-style supercharger to a 4-stroke engine.

The birth of the turbocharger, however, would come 5 years later, when Swiss engineer Alfred Büchi received a patent for an axial compressor driven by an axial turbine on a common shaft with the piston of the engine. Although this design wasn’t feasible at the time due to a lack of viable materials, the idea was there.

Turbochargers vs Superchargers

What idea was that, exactly? And how did it differ from supercharging?

I think it’s important to quickly go over the basic differences between turbocharging and supercharging. Both offer “forced induction” for piston engines. A naturally aspirated engine simply will draw in atmospheric air as the intake valve opens, and the piston travels down to bottom dead center. A forced induction engine, pushes more air into the cylinder than what the dropping of the piston would pull in, allowing more air to be combusted, and thus generating more power and efficiency. While turbochargers and superchargers are both forced induction , how superchargers and turbochargers go about compressing that air is different. Superchargers are driven by the engine themselves, typically via a belt or gear. This uses some of the engine’s available horsepower, but doing so provides more horsepower back to the engine. The compressors can be either positive displacement configurations (such as a Roots or Twin-Screw), or a  centrifugal supercharger.

supercharger configurations
A very helpful image of the 3 kinds of superchargers, courtesy of MechanicalBooster.com

Turbochargers, as mentioned before, use the air from the exhaust of the engine to drive a turbine, and the work of the turbine is transmitted on a common shaft to a compressor. The most common configuration is a radial turbine driving a centrifugal compressor similar to the one above in the supercharger diagram. However, there are other configurations ,seen in larger examples, such as an axial turbine driving a centrifugal compressor. Read More

Introduction to Performing Lateral Rotor Dynamics Analysis

Previous Blog  Next Blog

Hello and welcome to the Lateral Analysis section of our Rotor Dynamics Blog Series! If you haven’t had a look at the other entries in this series, you can find them here: Series Preface

  1. What is Rotor Dynamics? And Where is it Found?
  2. Why is Rotor Dynamics so Important?
  3. What API Standards Govern Rotor Dynamics Analysis?
  4. Basic Definitions and Fundamental Concepts of Rotating Equipment Vibrations
  5. The Purposes and Objectives of Rotor Dynamics Analyses
  6. The Importance of Accurately Modeling a Rotor-Bearing System­
  7. Modeling Bearings and Support Structures in a Rotor Bearing System

We’ve finally made it to the analysis part of the rotor dynamics and bearing analysis intro series! Let’s get into it, this blog will have a lot to cover!

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It’s Rocket Science – and it’s Dangerous!

Rockets have always fascinated us and to this day a rocket launch is still a global news event worth watching. The sheer noise, power and sight after you hear that “…3-2-1, Lift off!” leave us in awe. A masterpiece of engineering, the recent historic manned SpaceX Falcon 9 launch was no exception. Or was it?

The beginnings

From the outside, a rocket does not look especially advanced – a mere ‘stick’ with a big flame shooting out at one end. The principal concept is simple, too, but the inner workings of a modern liquid-fuel rocket are highly complex.

The first rockets are believed to have existed in China, around 1200. The invention of gunpowder was crucial to the development of these primitive rockets, which were fireworks initially and then weapons. Multistage so-called ‘fire arrows’ were documented during the early Ming Dynasty (Figure 1). The designs were based on bamboo sticks – still a little way off a Falcon 9.

Figure 1: The oldest known depiction of multistage rocket arrows, from 14th-century China. The top arrow reads ‘fire arrow’, the middle ‘dragon-shaped arrow frame’, and the bottom’complete fire arrow’. Source

With the rise of gunpowder, this crude rocket technology spread throughout the Middle East and Europe.

The next rocketry milestone came in the 1780s, when the Indian military developed Mysorean rockets with iron castings and successfully deployed them against the British East India Company. Read More

Micro Gas Turbines in Trains and Railroad Technology

Previous Blog

Welcome to this latest (and sadly, last) entry in the Micro Gas Turbines in Transportation series! Today, we’ll be having a quick look at micro gas turbines and their larger siblings, specifically the history of how they have been used in railroad locomotion and  what the future holds for micro turbines and railroad technology. We’ll also consider the advantages and disadvantages of using them to drive trains.

Rail transportation has been around in one form or another for longer than you might think. There are examples of wheeled carts running on fixed roads and tracks that prevented any deviation being used since the 6th century BC in ancient Greece.

Up until the late 18th Century, however, railroads were rather limited in what they could be used for, since there was no way of mechanically propelling the vehicles used. Rather, these railroads relied on humans, animals, or gravity to move the carts along the tracks. This changed when in 1784, the great Scottish inventor James Watt created and patented the first steam engine locomotive which was an improvement of a steam engine designed by Thomas Newcomen. Following this invention, engineers in the UK working on different projects such as Richard Trevithick and his development of the first high-pressure steam engine would lead to the first uses of locomotive-hauled railway. His invention would be used in Wales on a short 9 mile run from an iron-works in Penydarren to the Merthyr-Cardiff canal.(2)  On February 21st, 1804, the first trip took place on this railway using only steam propulsion.(2) However it wasn’t until George Stephenson’s creation paved the way for public use of steam engines like those created by James Watt on the rails, and in the coming years rail travel would play an important role not just in the United Kingdom but in the United States as well. This raises the question, where and when did turbines and turbomachinery come into play in rail travel?

George Stephenson's Locomotion 1 –
George Stephenson’s Locomotion 1 – image courtesy of Chris55 / CC BY-SA

Believe it or not, gas turbines in trains were being experimented with long before Frank Whittle and Hans von Ohain were designing them to take to the skies. As far back as 1861, the year that Abraham Lincoln became president of the United States, patents were being filed for a turbine that utilized ambient air mixed with combustion gasses to drive a turbine. As seen in patent 1633, Marc Antoine Francois Mennons created an engine that included all of the components needed in a modern gas turbine engine. It was called a “caloric engine” and it had a compressor (called a ventilator), combustion chamber (using ambient air and burned wood or coke), and a turbine to create work from the combustion gasses as well as a pre-heater (which he called a regenerating apparatus).(3)

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Modeling a Ground Source Heat Pump

Update – February 28, 2023: AxCYCLE and AxSTREAM NET are our legacy software packages depreciated by AxSTREAM System Simulation. System Simulation was born out of the union of the legacy AxCYCLE and AxSTREAM NET.

Ground source heat pumps (GSHP) are one of the fastest growing applications of renewable energy in the world, with annual increase of 10% in about 30 countries over the past 15 years.  Its main advantage is that it uses normal ground or ground water temperatures to provide heating, cooling and domestic hot water for residential and commercial buildings. GSHP’s are proving to be one of the most reliable and cost-effective heating/cooling systems that are currently available on the market and have the potential of becoming the heating system of choice to many future consumers, because of its capacity for providing a variety of services such as heat generation, hot water, humidity control, and air cooling. Additionally,  they have the potential to reduce primary energy consumption, and subsequently provide lower carbon emissions, as well as operate more quietly and have a longer life span than traditional HVAC systems. The costs associated with GSHP systems are gradually decreasing every year due to successive technological improvements, which makes them more appealing to new consumers.

The basic purpose of a GSHP is to transfer heat from the ground (or a body of water) to the inside of a building. The heat pump’s process can be reversed, in which case it will extract heat from the building and release it into the ground. Thus, the ground is the main heat source and sink. During winter, the ground will provide the heat whereas in the summer it will absorb the heat.

A GSHP comes in two basic configurations: ground-coupled (closed-loop) and groundwater (open loop) systems, which are installed horizontally and vertically, or in wells and lakes. The type chosen depends upon various factors such as the soil and rock type at the installation, the heating and cooling load required, the land available as well as the availability of a water well, or the feasibility of creating one. Figure 1 shows the diagrams of these systems.

Two Basic Configurations
Figure 1. Two Basic Configurations of GSHP Systems. SOURCE: [1]
In the ground-coupled system (Figure 1a), a closed loop of pipe, placed either horizontally (1 to 2 m deep) or vertically (50 to 100 m deep), is placed in the ground and a water-antifreeze solution is circulated through the plastic pipes to either collect heat from the ground in the winter or reject heat to the ground in the summer. The open loop system (Figure 1b), runs groundwater or lake water directly in the heat exchanger and then discharges it into another well, stream, lake, or on the ground depending upon local laws. Between the two, ground-coupled (closed loop) GSHP’s are more popular because they are very adaptable.
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