Assignment 6

Types of the turbocharger:

1. Single Turbo;
2. Sequential Turbo;
3. Twin Scroll Turbo;
4. Variable geometry Turbo;
5. Variable twin scroll Turbo;
6. Electric Turbo.

TURBOCHARGER EXAMPLE IN GT POWER:

The following are the examples from gt-powwer:

Fixed geometry turbocharger:

As before this is the simplest form of a TC and in this case the geometry is fixed, and without any control on the turbocharger's speed.

Variable Geometry TC or VGT:

In this type of TC, the TC's geometry can be controlled according to the speed. This helps in reducing the chances of mechanical failure and also helps to start the engine at low speed by closing the gates.

Wastegate TC

In this type of TC, the amount of exhaust gas going to the TC can be controlled using a pressure sensor. So if the pressure increases abive the limit then the small opening called wastegate opens and thus the pressure gets back to its limited value.

EXPLORING TUTORIAL 6 & 7:

This last engine model is a 6 cylinders direct injection diesel engine with an intercooler system. The main function of the intercooler is to cool down the hot air from the compressor for increasing the air's density. In this model, a twin scroll turbine is assumed and the assumed data is fed into the inlet and outlet boundary conditions.

This last engine model is a 6 cylinders DI along with and Intercooler and TC system. In this case, the TC is attached to the cylinder's exhaust. In addition the turbine and compressor maps are defined by the manufacturer which defines the working of the compressor and the turbine.

COMPRESSOR MAP:

TURBINE MAP:

In which application VGT is beneficial ?

VGT devices are essentially used for increasing the boost pressure at low speed, reducing response time, increasing available torque, decreasing the boost at high engine speeds to prevent over boosting, reducing engine pollutants, improving fuel economy and increasing the overall TC operating range.

Explore example-Diesel VGT EGR and understand the modeling part:

This last engine model is a 4-cylinders, four-stroke, direct-injection, 2L diesel engine. A predictive combustion model is being used with detailed injection profiles.

The intake system consists of the air piping upstream of the compressor inlet and contains a simple model of an airbox.

The intercooler is present which cools the compressed air.

The EGR system is present to decrease the temperature of the cylinders by mixing with the incoming air.

Exhaust gases enter the turbine radially and before entering the turbine there are some guiding through which we change the area to allow the required flow. Depending on the available kinetic energy and the required pressure ratios we can change the amount of kinetic energy going to the turbine.

VGT is defined in terms of rack position and for each rack position, the turbine maps are provided. An electronic controller also controls the rack position and for different speed-load conditions we have different possibilities of boost pressures. So here the boost pressure is provided as wireless signal.