Pressure Oscillation Characteristics of Compound Combustion for DME Engine

HOU Junxing; YANG Haipeng; ZHENG Lu; LI Shuhao; ZHANG Huayang; AN Xiaodong

Vehicle Engine ›› 2022, Vol. 0 ›› Issue (4) : 36-40.

HOU Junxing¹,YANG Haipeng²,ZHENG Lu²,LI Shuhao¹,ZHANG Huayang¹,AN Xiaodong¹

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Abstract

The pressure oscillation characteristics of DME compound combustion at different speeds were studied. The time-domain and frequency-domain characteristics were determined. The effect of the fuel amount introduced into the intake port on the sub-signal peaks of in-cylinder pressure in the different frequency-domains was investigated. The results show that the curve of heat release rate produces three stages and the spectrum curve of in-cylinder pressure level also produces three stages of rapid drop, slow drop and fluctuation when the intake fuel amount increases from 0.77 mg/s to 1.37 mg/s at 1 500 r/min. The law is also similar at 1 100 r/min. With the increase of intake fuel amount, the peak of low-temperature heat release part for HCCI combustion increases and the phase advances, the high-temperature heat release part changes from a single-peak to a doublepeak, and the diffusion combustion part fluctuates sharply. The sub-signals of low-frequency p₁, medium-frequency p₂ and high-frequency p₃ are obtained from the in-cylinder pressure by the band-pass filter, and the sub-signal of p₁ corresponds to the normal combustion pressure and the sub-signals of p₂ and p₃ correspond to the combustion pressure oscillation. The combustion state determines the peak value of each cycle for sub-signal of p₁, p₂ and p₃. As the intake fuel amount increases, the peak of each cycle for subsignal of p₁ increases. The peak of each cycle for sub-signal of p₃ is very small, and the peak of each cycle for subsignal of p₂ is significantly larger than that for sub-signal of p₃ in normal combustion. The peaks of each cycle for sub-signal of p₃ and p₂ increase significantly in the slight and severe pressure oscillation respectively.

Key words

dimethyl ether / compound combustion / pressure oscillation / time-domain characteristic / frequency-domain characteristic

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HOU Junxing,YANG Haipeng,ZHENG Lu,LI Shuhao,ZHANG Huayang,AN Xiaodong. Pressure Oscillation Characteristics of Compound Combustion for DME Engine[J]. Vehicle Engine. 2022, 0(4): 36-40