Development Of Optical Test Bench Based On GDI Engine

As a traditional power machine, internal combustion engine has being constantlyimproved along with the development of the automotive industry. Due to thesmoothness and comfort during its working, gasoline engine got a more rapiddevelopment in the field of small passenger cars. And the emergence of GasolineDirect Injection (GDI) engine has played an important role in the entire history ofgasoline, it has made the combustion efficiency of gasoline rose to a new level. Withthe improvement and maturity of this technology, there’re more and more gasoline carequipped with GDI engine. Meanwhile, it also has brought some huge challenges tous, which are related to harmful emissions such as particulate matter. In order toimprove the emissions of GDI engine, we need to intensively analysis and study thecause of those harmful substances. Therefore, a more accurate and effective testmethod for research on the working process of the engine would be necessary. Andoptical testing technology is one of the ideal choice.This technology has been used to measure parameters in engine cylinder byresearchers in the70s abroad. In comparison with the traditional cylinder measuringmethods, optical testing techniques have many advantages such as having slightlyinterference to the measured object, high sensitivity, and high resolution in time andspace etc. In recent years, with the development and improvement of the field ofoptics and related technologies, optical test technologies have become easier to useand have higher accuracy, which made it more widely been applied in the field ofinternal combustion engine. In order to apply these optical testing technologies inengine-related research, it is an important foundation to develop an optical testplatform that is able to simulate the actual working conditions of engine.Some typical optical testing technologies, common structures of optical enginesand their advantages and disadvantages have been described and analyzed in thisthesis. And the process of setting up the entire optical test platform based on a GDIengine with displacement of1.4liters also been presented. After the completion ofthis platform, its validity was tested through Planar Laser Induced Fluorescence(PLIF). Specific contents have been shown as follows:1. Provided optical paths with larger viewing access based on an inline4-cylinderGDI engine. Changes to the original machine structure were as little as possible, so that the costs and the number of redesigned parts could be reduced. Meanwhile it’salso able to shorten the development cycle and ensure the reliability of the designedoptical engine.2. Provided proper protection to quartz components used to achieve visualizationby reasonable structural design. At the same time, strength check to the two partsmade of quartz has been conducted for the purpose that to see if they can meet thestrength requirements, especially under the conditions of high temperature andpressure.3. To complete the modifications of the original structure of the engine, so thedeveloped optical engine could be provided with lubrication system, fuel system,cooling water temperature control system and valve timing mechanism with highwork stability.4. The modified optical engine has been connected with three-phase asynch-ronous AC motor, and the engine speed will be controlled through a frequency changer.5. After the development of this optical test platform, a PLIF optical test systemwas built based on it. In this PLIF optical test, acetone has been used as fluorescentagent, and the purpose of this test was to verify the potential of PLIF technology forthe research on forming process of the mixed gas. Apart from that, this test alsoindicated the effectiveness of this optical test platform for some optical experiments.