*Article* **Numerical Investigation of Fluid Flow and In-Cylinder Air Flow Characteristics for Higher Viscosity Fuel Applications**

**Mohd Fadzli Hamid <sup>1</sup> , Mohamad Yusof Idroas 1, Shukriwani Sa'ad 2, Teoh Yew Heng 1, Sharzali Che Mat <sup>3</sup> , Zainal Alimuddin Zainal Alauddin 1, Khairul Akmal Shamsuddin 4, Raa Khimi Shuib <sup>5</sup> and Muhammad Khalil Abdullah 5,\***


Received: 6 January 2020; Accepted: 13 February 2020; Published: 8 April 2020

**Abstract:** Generally, the compression ignition (CI) engine that runs with emulsified biofuel (EB) or higher viscosity fuel experiences inferior performance and a higher emission compared to petro diesel engines. The modification is necessary to standard engine level in order to realize its application. This paper proposes a guide vane design (GVD), which needs to be installed in the intake manifold, is incorporated with shallow depth re-entrance combustion chamber (SCC) pistons. This will organize and develop proper in-cylinder airflow to promote better diffusion, evaporation and combustion processes. The model of GVD and SCC piston was designed using SolidWorks 2017; while ANSYS Fluent version 15 was utilized to run a 3D analysis of the cold flow IC engine. In this research, seven designs of GVD with the number of vanes varied from two to eight vanes (V2–V8) are used. The four-vane model (V4) has shown an excellent turbulent flow as well as swirl, tumble and cross tumble ratios in the fuel-injected region compared to other designs. This is indispensable to break up heavier fuel molecules of EB to mix with the air that will eventually improve engine performance.

**Keywords:** piston bowl; alternative fuel; vanes; emulsified biofuel; biofuel
