Hasibul hasan who read many revisions for me and helped me understand the confusion. Also thanks to our board members, dr. The compressor compresses the air (for gasoline engines) or the air-fuel mixture (for diesel engines) that is fed into the engine.
The kinetic energy of the exhaust gases is returned to the engine and put to good use. A jet engine sucks in cool air from the front, compresses it into a chamber where it burns with fuel, and then blows hot air out the back. As the hot air leaves, it roars past a turbine (somewhat like a very compact metal windmill) that drives a compressor (air pump) at the front of the engine.
This is the bit that pushes the air into the engine to get the fuel to burn properly. A supercharger (or "mechanically driven supercharger" to give it its full name) is very similar to a turbocharger, but instead of being driven by exhaust gases using a turbine, it is driven from the car's rotating crankshaft. One of these fans, called the turbine, sits in the exhaust stream from the cylinders.
The second fan is called the compressor and because it is on the same shaft as the turbine, it also rotates.
Principle of compressor analysis
A turbocharger is actually two small air fans (also called rotors or gas pumps) that sit on the same metal shaft so they both spin together. As the cylinders blow hot gas past the fan blades, they rotate, and the shaft they're connected to (technically called a center hub rotating assembly, or CHRA) also rotates. It is located inside the car's air intake so that it pulls air into the car and pushes it into the cylinder as it rotates.
Fig. This illustration highlights the areas where foreign matter affects the compressor and turbine wheel inductors and causes turbo failure. However, many specialist independent turbocharger distributors will employ at least one senior technician trained in failure analysis. For many people, the very concept of telling which part of the catastrophic failure was the cause is extremely puzzling.
However, just as medical experts can perform an autopsy on a cadaver to determine the cause of death, a trained technician can analyze the turbocharger's components and discover the likely cause of failure. In this way, failure analysis can be invaluable in helping to correct the conditions and therefore avoid a repeated failure. Although there are many types of turbocharger failures and reasons for these failures, the 80/20 law applies just as it does to most statistical situations.
This chapter is devoted to the diagnosis of turbocharger malfunctions and, more importantly, the interpretation of these malfunctions and how to use the findings to correct the situation. While most commercial failure analysis reference manuals address commercial diesel applications, this section uniquely considers performance applications as well, providing a reference for both performance enthusiasts and professionals in the turbo service industry.
Understanding Turbocharger Failure Analysis
This often happens when the failure starts in one place, moves to the next part, and the next, until there is significant damage to the entire turbocharger. Then finding out what came first can be the difference between getting the cause right and wrong. The goal of this chapter is to help teach a fundamental approach to correctly determining the cause of an error so that corrective action can be taken to avoid unnecessary repetitions.
Beginning the Analysis: The External Examination and Notation
Although these four reasons account for almost all errors, there are many more reasons to discuss. While there will undoubtedly be failure modes not addressed in this chapter, we'll get to about 90 percent, making this as comprehensive a guide as currently available on the open market. This can be done by removing either the bolts that tighten the clamp pins that hold the turbo together, or by loosening the V-band clamps.
If FOD (foreign object damage) is the cause of the failure, it will be obvious at this point. Foreign object damage is currently a conclusive diagnosis and is perhaps the easiest and quickest to diagnose. However, look closely at the turbine side if this is the side where damage is visible.
There are fault conditions similar in nature to FOD on the turbine end inductor. Fig. Note the smooth damage around the inducer area and the metal scraped and torn from repeated impacts from a foreign object.
Compressor End
- TURBOCHARGING OVERVIEW
- THE TURBOCHARGER RIG
- WORKPIECES
- SENSORS AND CALIBRATION FUNCTIONS
- The Oil Pressure Sensor
Since the beginning of the twentieth century, until today, the car has become the most productive form of transportation. To circumvent some of these operational aspects, hybrid vehicles combining thermal engines with electric propulsion are beginning to be available on the market. Currently, some of the major car manufacturers sell hybrid cars, such as: Toyota Prius, Honda Jazz, Citro¨en DS5, Peugeot 3008 Hybrid, to name just a few.
Among other approaches, a variable geometry turbocharger has a set of wheels in the exhaust housing to maintain a constant gas velocity across the turbine. Consequently, part of the pressure increase is due to heating of the air before it enters the engine. Due to common simplifications used in the models, one decided for this work to build a controller that has at its core a real commercial turbocharger: the Garrett's GT1749v turbocharger which is from ' A Renault Laguna 1.9 DCI (120 hp) was removed.
The system, which will be discussed in the following sections, will be used as a testbed for several different control algorithms. In the referenced figure, the inlet shown by number (6) relates to the turbine compressed air inlet. One of the big challenges was devising a way to keep oil under pressure inside the turbocharger gasket.
Since bearing failure can quickly cause rotor wear, an oil pressure sensor (7), in this case FAE14540, was installed in the oil circuit. On the left is a picture of the CNC machine used in the production process: Dekel Maho DMC 63V. On the right, a detail of the almost finished piece (in this case, one of the stepper motor connectors).
The ring represented on the top of the assembly will be used to determine the zero position of the scale. On the left an exploded view of the 3D model and, on the right, the aforementioned part already installed on the turbocharger. In the created configuration, some of the sensors are real and others are emulated by software (during engine operation).
This is a resistive type sensor capable of measuring pressures in range from 0 to 1 GPa. Since the sensor is specially designed for automotive application, the mounting is done through a 12mm/1.5mm screw and one of the resistance poles is the metal housing of the sensor.
Result and Discussion
They also have a lot in common like high pressure direct fuel injection ("FSI"), same number of cylinders etc. Additionally, the naturally aspirated engine uses a compression ratio one higher than the turbo engine, and the turbo engine develops 34 percent more peak power than the naturally aspirated model. So far, – apart from the very high compression ratio of the turbo engine – everything is as it has been for more than two decades with turbocharging. Therefore, when you drive the turbo car, the engine requires far fewer gear changes (whether manual or via an automatic gearbox) and thus stays more often at lower engine revs.
Despite having a lot more power at the top end, for economy it's the power available at the bottom end of the rev range that really matters - and the Turbo 2.0 FSI has that in spades. Going further, to prove that the turbo is more efficient than compared to its naturally aspirated opponent, Skoda took the same 2 liter engines and compared it to a 1.8 liter turbocharged engine, the numbers were again astounding. So even though it's a smaller engine, the turbo 1.8 easily outperforms the naturally aspirated 2-litre at the critical-for-economy bottom end of the rev range.
And of course, it does even better in fuel economy – 7.7 litres/100km and CO2 emissions of 184 grams/kilometre. However, what is most important for today is the issue of fuel efficiency and here the turbocharger outperforms the naturally aspirated engines. In the Australian government test cycle, the naturally aspirated Skoda 2.0 FSI has a fuel consumption of 8.5 litres/100km, while the turbo 2.0 FSI has a tested economy of 8.1 litres/100km.
The CO2 emissions are also as you would expect by now: 203 grams / kilometer for the atmospheric engine and 193 for the turbo.*6+. Increasingly stringent emission regulations around the world are challenging automakers to create engines that meet the needs of the environment while meeting consumer demand for vehicles that are fun to drive. Because the size of the turbocharger is chosen to produce a certain amount of pressure at high altitude, the turbocharger is too large for low altitude.
As the aircraft climbs and the air density drops, the vent valve must continually close in small increments to maintain full power. The altitude at which the vent valve closes completely and the engine still produces full power is the critical altitude. As the aircraft climbs above a critical altitude, the engine's power output decreases with increasing altitude, just like a naturally aspirated engine.
A turbocharger alleviates this problem by compressing the air back to sea-level pressure (turbo-normalization), or even much higher (turbo-charging), to produce rated power at high altitude. When the aircraft is at low altitude, the wastegate is normally fully open and vents all the exhaust gases overboard.
