AI Summary & Key Takeaways
AI InsightIt was found that the nozzle vane undergo cyclical loading at a maximum stress of 58 MPa for 109 cycles of operation at an inlet temperature of 800oC and pressure of 240 kPa.
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Abstract
This paper investigates nozzle material candidates for use in a turbocharger turbine technology known as the active control turbocharger (ACT) which is a distinct technology to the Variable Geometry Turbine (VGT) for turbochargers, but broadly based on this technology. In this concept an actuated nozzle mechanism is oscillated to provide a continuous change of the turbine inlet area in response to the instantaneous exhaust gas flow pulsating characteristics to provide greater extraction of exhaust gas pulse energy. Careful materials selection is required for this application to overcome the creep, fatigue, oxidation and high temperature challenges associated with the diesel engine exhaust conditions to which the nozzle is exposed to. The investigation of materials suitability for this application was conducted for steady and transient flow conditions. It was found that the nozzle vane undergo cyclical loading at a maximum stress of 58 MPa for 109 cycles of operation at an inlet temperature of 800oC and pressure of 240 kPa. The vane experiences maximum stresses in the closed position which occurs at a vane angle of 70o. It has been found that the implementation of ACT technology is possible using currently available materials. A material selection process was developed to incorporate the specific application requirements of the ACT application. A weightinG decision process was applied to analyse the importance of various material properties to each application requirement and to the properties of individual materials. Nimonic 90 and IN X750/751 obtained the highest overall scores from the selection process and were shown to be capable of withstanding the creep requirements; a failure mechanism of primary concern in the high temperature application. Nimonic 80A, although receiving a final rating 8% lower than Nimonic 90, also showed promising potential to offer a solution, with superior corrosion properties to both Nimonic 90 and IN X750/751