Turbocharger Functioning Explained: An Overview
Soaring high: A guide to turbochargers and flying at high altitude
Blasting off to higher altitudes can offer perks like reduced drag, increased speed, and stronger tailwinds. But there's a downside to these flight levels for normally aspirated engines: a deficit of oxygen.
The oxygen shortage problem
As we ascend, air pressure plummets, and it does so steeply. At an altitude of 18,000 feet, about half of the atmosphere lies below you, meaning less air for your engine to burn and lower horsepower coming out of your aircraft.
Solving the thin air dilemma with turbochargers
Turbochargers neatly address the problem of slim air by compressing the intake air before it enters the cylinder. This way, your engine operates as if it's sitting at sea level or even lower, regardless of the flight level.
Understanding the mechanics of turbocharging
Turbochargers consist of three main components: a turbine, a compressor, and a shaft that connects the two. Here's a lowdown on these components:
The turbineThe process begins with the turbine, which is powered by the exhaust gas exiting your engine. As exhaust exits via the exhaust manifold, it brushes past the turbine, causing it to spin. The faster the exhaust passes, the quicker the turbine rotates. Simple as that, for now.
The shaftA shaft links the turbine and the compressor, so once the turbine starts spinning via engine ignition, the compressor follows suit.
The compressorThe compressor is responsible for drawing in air (from outside the airplane), compressing it, and transferring it into the engine. It's also connected to the turbine through the shaft.
Now, let's dive deeper into the workings of a turbocharger.
Managing oversupply of air: Wastegates
Turbochargers can sometimes produce excess manifold pressure, which can wreck your engine. To prevent an air glut, wastegates come into play.
Some wastegates are automatic, while others are piloted-controlled, but their theory remains the same. A wastegate opens and closes to control the amount of exhaust gas flowing over the turbine and prevents the turbine from spinning too rapidly. When the turbine spins faster, the compressor follows suit, pulling in more air for the engine.
But how much air can your engine handle?
Engine tolerance for air intake differs, but turbocharging primarily involves two types: altitude turbocharging and ground boosting.
Altitude turbochargingAltitude (or 'normalizing') turbocharging maintains engine performance as close to sea level as possible, as long as possible. It depends on the engine, but most altitude turbochargers keep manifold pressure between 29-30 inches of mercury (sea level pressure) as you ascend in altitude.
However, as altitude escalates, the turbocharger gradually becomes unable to compress enough air to retain sea level pressure. This is known as the critical altitude, beyond which your engine can no longer produce its maximal horsepower (engine horsepower is rated at sea level).
From this point, the higher you go, the less air your engine receives, resulting in declining horsepower. Nevertheless, this setup still outperforms a normally aspirated engine significantly.
Ground boostingGround boosting, similar to altitude turbocharging, employs higher manifold pressures—typically between 31-45 inches of mercury. This setup offers more airflow into the engine and, in turn, greater horsepower output.
However, this approach comes with a detrimental drawback: excessive heat.
Turbochargers and their heat quandaries
As air is compressed, it becomes hotter. This is one of the principal downsides of any turbocharger. Aircraft engines already generate high temperatures, and hot intake air worsens the situation. To counter the problem, many turbochargers implement an intercooler.
An intercooler is essentially an air conditioner stationed in between the turbocharger and the engine. As the hot air traverses from the turbo to the engine, it passes through the intercooler, and its temperature significantly drops. This cooler air pleases the engine and ensures it keeps performing efficiently.
The high altitude edge
Turbochargers play a critical role in enabling piston-driven aircraft to ascend to the flight levels for robust tailwinds, increased true airspeed, and breathtaking views. While they add some complexity to the engine system, they're essential for racking up the miles at high altitudes.
Resources
- HowTurbochargersWork - HowStuffWorks
- The Basics of Turbocharging - FlugKerl2
- Turbochargers: What is a Turbo and How Do They Work? - Boldmethod
- How Does a Turbocharger Work? - HowEngineeringWorks
- Complete Guide to Turbocharging - TransmissionYOU
- In the realm of space-and-astronomy, the technology behind turbochargers can be likened to rocket engines, as they both rely on compressing air to increase power and fuel efficiency.
- Despite the advantageous points of flying at high altitudes, the deficit of oxygen can pose a challenge to both airplanes and aircraft engines, a problem that turbocharging addresses using data-and-cloud-computing methods to manage the optimal amount of air intake.
- Turbochargers, essential components in piston-driven aircraft, are not only capable of improving horsepower and speed but also play a crucial role in the development of aviation science and technology, as they enable aircraft to soar higher while reducing drag.
- Engineered with a blend of science and technology, the intricate mechanics of a turbocharger – turbocharger, compressor, and shaft – function like a well-oiled machine, harnessing exhaust gas to compress air more efficiently, extending flight range at high altitudes.
