Abstract
With increasing environmental concern Emission legislation is becoming stern. Simultaneously fuel economy, performance, safety and drivability of the vehicles are getting advance. To meet the above necessity usages of advance turbocharged Diesel/Gasoline engines are being increased in every automobile. Turbochargers have developed as one of the widespread technologies worldwide over the time; even though the current turbocharger system has some drawbacks. In the country like India where customers have started to pay attention on the driveability and comfort the car innovative design is required to produce the accurate boost to the engine. The basic concern of the current turbocharger is overcoming the issue of turbo-lag and excessive boost which is caused due to lower rpm reaction to the drivers commands which is due to its inertia and excessive pressure which is created at higher rpm. The current paper deals with the design and simulation of a novel type of turbocharger, called Variable position Turbocharger (VPT), which contains very simple mechanical design to overcome the disadvantages of turbo lag and control the boost pressure. Most of the axial resultant force is unused due to the radial motion of the turbine shaft system. The spring actuation mechanism is designed which has a particular tension which actuates when there is excessive boost which allows to release of excessive pressure. The unused axial pressure of the exhaust gas can be used to move the turbine in axial direction to adjust the lag and boost. The simulation was conducted from CFD-Fluent. The total nodes were restricted to10138, to reduce the simulation complexity. The rotation of the turbine was considered at 6 different positions from base to tip (0.12 - 5mm). The boundary condition of 0.0158Kg/s mass flow rate and 800K temperature was given respectively for all 6 positions. As the position of the turbine changes from base to tip there is decrease in rpm of the turbine. The position of impact of exhaust gas on turbine changes due to the change in the position of the turbine which results in change in torque. When the impact is 0.12 mm the torque is highest which counters the lag and when the position of the turbine is 5mm away there is consecutive decrease in the torque which reduces the excessive boost. CFD simulation of the design was conducted which has its own constrain when compared to the experimental. The observation was recorded as compared to the simulation. Turbo balancing is a complicated subject when compared to turbocharger and increases the complexity of the simulation so only transient fluent simulation was performed in present research. Present turbocharger uses VGT which is a complex device and high cost. Whereas waste gate is less cost effective but not that efficient when compare to turbo lag. The present design offers the simple mechanism to actuate the axial force and change the torque which will effect the extensive boost and turbo lag. The system works on simple spring actuation mechanism which is cost effective as compared to the present used models. The current design reduces the complexity and the feedback system and integrates the system in single component. Due to the different position of the turbine there is decrease in torque from base to tip so high torque creates high boost at the base. As the exhaust gas impacts moves towards the tip there is decrease in rpm and pressure which reduces the excessive boost.