| The dissertation is emphasized on the improvement of a total cylinder sampling system, and based on the improved system, the formation history of in-cylinder particulate during diesel combustion has been investigated. The major achievements are listed as follows:1. The sampling hole and the location of the pressure sensor bushing were redesigned through 3-dimension simulation with Pro-E. The fine thread and sealing gum of high temperature resistant were utilized for airproof. The cutter tube was also improved to ensure the convenient pucker and to avoid an accident. Moreover, a stable, controllable device which could simulate the turbocharged intercooler system was established.2. A new cylinder pressure acquisition system was built. The system can precisely determine the nominal sampling crank angle and monitor the combustion condition effectively.3. By means of the electromagnetic valve and flowmeter to control the dilution gas, the dilution system was able to drop down the temperature of sampling gas quickly, freeze the chemical reaction and gauge the flow accurately.4. With the improved total cylinder sampling system, the formation history, shape character and physiochemicasl property of in-cylinder particulate under different diesel engine operating conditions were preliminarily investigated. The experiment results indicate that mass concentration of particulate shows unimodal distribution, and the peak point lies at about 20°CA ATDC, corresponding to the diffusion combustion phase of diesel combustion. The soot particles are oxidized by about 70~80% in the late combustion phase. And then, the mass concentration of particulate equals to the concentration in the tail pipe. Particulates are in chain structure and agglomerated by elementary particles of sphere-like structures. The size of elementary particles is between 20~42 nm, and the contents dominately consists of what are amorphous carbon and microcrystalline carbon.
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