Experimental study on ignitabilityoflean CNG/air mixturein the multi-stage cascade engine combustion system

Format:

Book

Conference/Event

Author/Creator:

Bueschke, Wojciech, author.

Contributor:

Szwajca, Filip

Wisłocki, Krzysztof

Conference Name:

SAE Powertrains, Fuels & Lubricants Meeting (2020-09-22 : Krakow, Poland)

Language:

English

Physical Description:

1 online resource cm

Place of Publication:

Warrendale, PA SAE International 2020

Summary:

Lean air-gas mixture combustion systems seem to be very promising solutions for IC engines in terms of lower emission indexes and higher thermal efficiency, especially in part-load operation. The main problem however is the necessity to provide the bigger activation energy for ignition of lean and very lean mixtures. In the preceding investigations reported in several publications and in research performed by the authors of this paper it has been confirmed, that the implementation of turbulent jet ignition (TJI) results in significantly faster inflammation of lean CNG/air mixture due to the improvement in on-ignition mechanism. The TJI-system consists of two chambers connected with nozzles, which provide charge exchange between them. The orifices generate complex charge movement during the mass transfer to the pre-combustion chamber and decrease significantly the charge homogeneity in the pre-combustion chamber, interrupting therefore first ignition process. The main research question of the investigations reported in this paper was to improve this unfavorable property and to validate better inflammation ability in the pre-chamber by applying additional small auxiliary combustion chamber integrated with spark plug in order to change inflammation mechanism in pre-chamber, creating together the 3-stage combustion system. Three types of combustion systems (conventional 1-stage, 2-stage and 3-stage) have been investigated for the comparative validation of main combustion efficiency indexes.The investigations have been performed using pneumatically driven Rapid Compression Machine (=15) with both indicating measurements and broadband chemiluminescence optical method. The images have been recorded using high-speed camera and post-processed with the LaVision Davis software for the parameterization of inflammation intensity and flame front velocity. Investigations have been performed at λ=1.5. In the first step the study on the spark plug with additional combustion chamber has been performed, which has been than installed on the top part of the pre-combustion chamber of turbulent jet igniter and investigated. On this basis the on-ignition capability of three-stage combustion system has been proven. The occurrence of luminescent jets in the main combustion chamber indicates delay in comparison to the prechamber system with conventional spark plug. However, in the further time instances, three-stage combustion resulted in bigger flame luminescence confirmed by bigger heat release rate obtained in indicating measurements, finally combined with earlier completing of combustion. Introduction of third stage resulted in shorter combustion duration of defined fuel quantity. The delay in ignition of main charge indicates further potential to be compensated with ignition advance adjustment. The results achieved in the model engine (RCM) have been verified in the one-cylinder research engine under real operation and complemented with the measurement of exhaust gas toxic compounds emission. Achieved test results according flame maximal temperature, flame front propagation velocity, combustion duration and emission of toxic compounds have been presented comparatively for all three investigated combustion systems

Notes:

Vendor supplied data

Publisher Number:

2020-01-2084

Access Restriction:

Restricted for use by site license