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Study of liquid fuel transport in a small carburetted engine in the context of cold-start HC emission control

Tewari, Sumit and Anand, TNC and Nishikant, MP and Ravikrishna, RV (2014) Study of liquid fuel transport in a small carburetted engine in the context of cold-start HC emission control. In: SADHANA-ACADEMY PROCEEDINGS IN ENGINEERING SCIENCES, 39 (3). pp. 549-571.

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In the present study, a detailed visualization of the transport of fuel film has been performed in a small carburetted engine with a transparent manifold at the exit of the carburettor. The presence of fuel film is observed significantly on the lower half of the manifold at idling, while at load conditions, the film is found to be distributed all throughout the manifold walls. Quantitative measurement of the fuel film in a specially-designed manifold of square cross section has also been performed using the planar laser-induced fluorescence (PLIF) technique. The measured fuel film thickness is observed to be of the order of 1 nun at idling, and in the range of 0.1 to 0.4 mm over the range of load and speed studied. These engine studies are complemented by experiments conducted in a carburettor rig to study the state of the fuel exiting the carburettor. Laser-based Particle/Droplet Image Analysis (PDIA) technique is used to identify fuel droplets and ligaments and estimate droplet diameters. At a throttle position corresponding to idling, the fuel exiting the carburettor is found to consist of very fine droplets of size less than 15 mu m and large fuel ligaments associated with length scales of the order of 500 mu m and higher. For a constant pressure difference across the carburettor, the fuel consists of droplets with an SMD of the order of 30 mu m. Also, the effect of liquid fuel film on the cold start HC emissions is studied. Based on the understanding obtained from these studies, strategies such as manifold heating and varying carburettor main jet nozzle diameter are implemented. These are observed to reduce emissions under both idling and varying load conditions.

Item Type: Journal Article
Additional Information: Copy right for this article belongs to the INDIAN ACAD SCIENCES, C V RAMAN AVENUE, SADASHIVANAGAR, P B #8005, BANGALORE 560 080, INDIA
Keywords: Carburettor; small engines; cold-start HC emissions; fuel film visualization; PLIF; PDIA; droplet sizing; backlit visualization
Department/Centre: Division of Mechanical Sciences > Mechanical Engineering
Date Deposited: 19 Aug 2014 09:08
Last Modified: 19 Aug 2014 09:08
URI: http://eprints.iisc.ac.in/id/eprint/49561

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