Browse Publications Technical Papers 2019-28-0024
2019-10-11

Optimization of In-Cylinder Flow and Swirl Generation Analysis for a Naturally Aspirated Diesel Genset Engine for Emission reduction through Intake Port Design 2019-28-0024

KEYWORDS - Intake port design, In-cylinder flow, steady flow test, CFD numerical simulation, emission reduction & fuel economy Engine in-cylinder flow structure governs the combustion process and directly influences emission formation and fuel consumption at the source. In naturally aspirated DI diesel engine combustion process, coupled with low pressure mechanical fuel injection systems set different requirements for inlet port performance. In-cylinder swirl needs to be optimized for efficient combustion to meet emission levels and fuel consumption targets. Thus, intake port design optimization process becomes a vital requirement. In the present paper intake port design optimization is carried out for single cylinder naturally aspirated engine using mechanical fuel injection systems. The objective is to investigate in-cylinder flow field developed by intake port designs. Study the effects of geometrical details of various port cross sections on flow velocity and pressure fields and establish a relationship with intake port performance parameters i.e. swirl and flow coefficient. Further, the impact of these new intake port designs on off-highway diesel engine emissions and performance is evaluated. Thus the focus is given to create a port performance evaluation design guidelines for future combustion system development. Two intake port geometries with 2.5 & 2.0 swirl levels are designed by defining a structured pattern of various cross sectional areas. These port designs are experimentally evaluated on steady state flow test rig using AVL paddle wheel method for swirl and flow coefficient performance. A detail numerical analysis is carried out using AVL FIRE CFD simulation software to understand in-cylinder flow distribution. Effect of geometrical parameters on flow velocity and pressure drop is studied. The variation in flow structure at major cross sections with reference to each valve lift position is studied and compared for two design variants of intake port. Finally, both these new port designs are tested on single cylinder DI diesel engine for genset application. The impact of intake port variants on engine emissions and fuel economy is evaluated through 5-mode emission test cycle. Intake port with reduced swirl level has given promising results with better margin with respect to emission limits. Thus, in order to reduce NOx and PM levels without deteriorating fuel consumption, optimized swirl generation through intake port design is achieved. Detail design guidelines for intake port on the basis of cross sectional areas with desired performance are established through this study. This will lead to develop a robust technique for intake port development for future emission norms with better fuel economy.

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