Center Floor Undercover Air Guide Development to Improve Aerodynamic Drag for a Passenger Car
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ght © 2020 KSAE/ 11715 pISSN 12299138/ eISSN 19763832
CENTER FLOOR UNDERCOVER AIR GUIDE DEVELOPMENT TO IMPROVE AERODYNAMIC DRAG FOR A PASSENGER CAR Se Rok Yang1), Hyun A Choi1), Ho Gyun Moon1), Moon Sang Kim1)* and Ju Yeol You2) Department of Aerospace and Mechanical Engineering, Korea Aerospace University, Goyang 10540, Korea Research & Development Division, Hyundai Motor Company, 150 Hyundai Yeonguso-ro, Hwaseong 18280, Korea 1)
2)
(Received 1 November 2019; Revised 23 December 2019; Accepted 23 December 2019) ABSTRACTCooling airflow is essential to the vehicle air conditioning system and engine cooling module. The cooling airflow in the engine room flows out through the front subframe, front wheelhouse, roll-rod, etc. and mixes with the upstream external flow in the underbody of the vehicle so that it affects the aerodynamic drag on the rear part of the vehicle. An air guide is developed to reduce the aerodynamic drag. It is attached on the center floor undercover and induces cooling airflow exited from the engine room to flow to the rear section of the underbody of a vehicle. It can reduce up to 2.3 % of the aerodynamic drag of baseline vehicle. Numerical flow simulations are performed at the velocity of 140 km/h vehicle driving condition. KEY WORDS : Cooling airflow, Center floor undercover, Air guide, Aerodynamic drag reduction, Numerical flow simulation
NOMENCLATURE
vehicle, 10 % induced drag, and 70 % shape drag (Auto Journal, 2013). Cooling drag occurs as the cooling airflow enters the engine room. Cooling airflow is essential for air conditioning system and internal combustion engine cooling. As the cooling airflow flows out through the engine room to the underbody of a vehicle, the cooling airflow mixes with the on-coming upstream external flow so that the aerodynamic drag on the rear part of the vehicle is affected. Various studies have been conducted to improve drag generated by the cooling airflow. Studies on the principle and phenomenon of cooling resistance have been accomplished by Wickern et al. (2006), Williams and Stevens (2006), Gillieron and Chometon (2001), and Xu et al. (2013). The effect of cooling resistance on fuel efficiency is also studied by Baeder et al. (2011). The influence of cooling airflow on the engine room has been studied by many researchers (Saab et al., 2013; Ha et al., 2017; Kim, 2016; Kubokura et al., 2014; Jama et al., 2006). The goal of this research is to develop a very simple device called air guide to reduce aerodynamic drag. A sedan-type commercial vehicle is chosen as a baseline vehicle and numerical simulations are performed using ANSYS Fluent 16.0 which is a very well-known commercial flow solver (FLUENT, 2015). Han et al. (2013) verified the FLUENT by comparing their numerical solutions with experimental results around an Ahmed body.
A Cd D V Cd
: frontal projection area of a vehicle, m2 : aerodynamic drag coefficient : aerodynamic drag force, N : airflow velocity, m/s : aerodynamic drag coefficient difference of a vehicle Cd rear section : aerodyn
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