Engine cooling airflow의 공기 저항에 관한 수치적 연구

송봉하(Bongha Song),이규익(Kyuik Lee),하종백(Jonpaek Ha) 한국자동차공학회 2011 한국자동차공학회 부문종합 학술대회 Vol.2011 No.5

These days, the fuel economy of road vehicles is getting important all over the world due to the several reasons such as the depletion of fossil fuel, high fuel cost, and stringent regulation of toxic exhaust gas from conventional internal engine combustion. Therefore, all auto makers are requested to develop a vehicle with high fuel efficiency as a demand of times. In this view point, aerodynamics can contribute considerably to solve these demands from customers. Total drag of road vehicle is mainly composed of three parts, exterior skin effect from upper body, underbody effect, and cooling drag. Especially, drag increment from engine cooling airflow need to be minimized for better aerodynamic and powertrain cooling performances through the optimization of front-end styling. Aerodynamics friendly front-end styling is completed by the grille inlet opening and CRFM sealing which are represented by baffle and gap seal. In this research, the drag impact on cooling airflow is studied using CFD analysis. The analysis results showed that grille inlet opening can be closed by reducing the cooling air leakage from grille inlet airflow to heat exchanger. Finally, the closing of non-effective opening are through the optimization of CRFM sealing using baffle and gap seal gave us dramatic aerodynamic saving effect, and therefore it helps the fuel economy.

냉각 공기 유동 최적화를 통한 공력 성능 향상에 관한 수치적 연구

송봉하(Bongha Song),이규익(Kyuik Lee),하종백(Jongpaek Ha) 한국자동차공학회 2011 한국자동차공학회 학술대회 및 전시회 Vol.2011 No.11

These days, the fuel economy of road vehicles is getting important all over the world due to the several reasons such as the depletion of fossil fuel, high fuel cost, and stringent regulation of toxic exhaust gas from conventional internal engine combustion. Therefore, all auto makers have been requested to develop a vehicle with high fuel efficiency as a demand of times. In this view point, aerodynamics is well known as a big potential which can contribute considerably to solve these demands from customers. Total drag of road vehicle is mainly composed of three parts, exterior skin effect from upper body, underbody effect, and engine room’s flow recirculation effect driven by engine cooling air flow. Especially, drag increment from engine cooling air flow needs to be minimized for better aerodynamic performance through the optimization of front-end styling. However, P/T cooling performance has also to be considered carefully because there is a trade-off relationship between aerodynamics and engine cooling performance. In this research, the drag impact on cooling air flow was studied using CFD analysis. Aerodynamics friendly cooling air flow system is completed by the optimization of front grille inlet opening, cooling air outlet, and CRFM sealing, which is represented by baffle and gap seal. The analysis results showed that grille inlet opening could be closed by reducing the leakage of cooling air flow from grille inlet to heat exchanger. Finally, the closing of noneffective grille inlet opening driven by the optimization of CRFM sealing using baffle and gap seal gave us dramatic aerodynamic saving effect, and therefore it will help the fuel economy. The size of cooling air outlet also showed that the bigger the size, the better the aerodynamic performance.

연비향상을 위해 최적화된 opening을 이용한 aerodynamic front end styling

이규익(Kyuik Lee),송봉하(Bongha Song),하종백(Jonpaek Ha),이태원(Taewon Lee) 한국자동차공학회 2010 한국자동차공학회 부문종합 학술대회 Vol.2010 No.5

As the environmental disruption caused by the vehicle is emerged, new vehicles with high fuel efficiency are needed. To improve fuel efficiency, vehicles have certainly the low aerodynamic drag coefficient. This paper is mainly purposed to reduce aerodynamic drag coefficient using the optimized opening for fuel efficiency front end styling by using CFD analysis. There are two ways to reduce aerodynamic drag coefficient in this paper. First one is to lower air leakage from front opening to CRFM module. Second one is to have the optimized opening. As a result, this paper showed that aerodynamic drag coefficient was reduced by lowering leakage and front opening. Also engine cooling performance was increased with aero-friendly styling.

전기자동차 냉방 시스템의 운전 조건이 Driving Range에 미치는 영향에 대한 연구

권지원(Jiwon Kwon),송봉하(Bongha Song),김용석(Yongsuk Kim) 한국자동차공학회 2015 한국자동차공학회 부문종합 학술대회 Vol.2015 No.5

CFD analysis를 이용한 Fuel filling pipe-line 설계

이규익(Kyuik Lee),송봉하(Bongha Song),하종백(Jonpaek Ha) 한국자동차공학회 2010 한국자동차공학회 학술대회 및 전시회 Vol.2010 No.11

When filling the gas tank, the gas dispenser is shut off long before the tank is filled. It’s called PSO(Premature Shut-Off). Generally, this problem occurs when the filler pipe from the nozzle to the gas tank fills up with fuel and operates a sensor located on the pump nozzle. A sharp bend in the pipe causes the fuel rushing into the inlet to accumulate at the top of the pipe rather than move directly into the gas tank. When the fuel swirls around in the pipe, it creates a blockage, causing fluid to back up in the filler pipe. The nozzle of the fuel pump has a sensor that turns the pump off as soon as it is surrounded by liquid. This simulations are for the fuel to travel from the fuel inlet to the gas tank while avoiding obstacles along the way. This paper is mainly purposed to avoid this phenomenon through the optimized pipe design by using CFD analysis. As a result, the simulations indicate that CFD can be successfully utilized as a tool to shorten the design, development and cost reduction cycle of a nozzle, filler pipe, canister, and tank system.

2016 쉐보레 더 넥스트 스파크 공력성능 개발

김용년(Yongnyun Kim),강선제(Sunje Kang),송봉하(Bongha Song),김용석(Yongsuk Kim) 한국자동차공학회 2015 한국자동차공학회 학술대회 및 전시회 Vol.2015 No.11

This paper presents the development on the Aerodynamic performance of the 2016 Chevrolet the Next Spark. This 2016 Spark is fully changed on the exterior styling and the architecture comparing from its previous version released in 2009 and it was conducted to improve Aerodynamic performance to support fuel economy and fuel consumption. To reduce the drag of the 2016 Spark, Exterior skin is fully optimized to have best Aerodynamic performance. And several Aerodynamic treatments are applied such as flat underbody, low leakage for cooling flow, and add-on Aerodynamics devices. Biggest contribution on drag of the vehicle is coming from exterior surface and underbody shape. This 2016 Spark was developed to have better drag coefficient on these exterior surface and underbody shape. For reducing drag on the exterior surface, it was conducted to optimize the exterior surface cooperated with Exterior studio from early development stage. In this development, Aero was involved from proportion development of the vehicle and theme development. This new vehicle is able to get 58 counts drag reduction from its initial styling model. And for reducing drag on the underbody structure, this vehicle is applied not to have vertical wall on the underbody structure decreasing pressure load. General vehicle and previous version of the Spark have vertical wall on the underbody structure against flow direction to support vehicle safety, but this 2016 Spark is adopted and designed flat underbody structure considering not hurting vehicle safety in early stage of development. This concept was contributed to reduce drag on the underbody structure. Also, this vehicle is developed low leakage cooling flow between the grill and the radiator. The 2016 Spark is reduced 8% - 19% in each powertrain variant comparing to the previous version. This improved cooling flow leakage contributes drag reduction decreasing non-effective flow goes into the engine room. And this vehicle adopted the enhanced airdam, Aerodynamic friendly OSRVM, D-pillar applique integrated roof spoiler, and edged side corner on taillamp, etc. In this development, Aero spends 344 hours for wind tunnel test of the 2016 Spark. And, there was 38 simulation runs for Aero CFD analysis and there was 5 times architecture change reflecting changed body structure. This development was supported to reduce drag 8.3% from the previous Spark and the 2016 Spark is able to lead Aerodynamic performance in the A segment.

Hood Deflector 공력최적설계

허도영(Doe Young Hur),이동현(Donghyun Lee),송봉하(Bongha Song) 한국자동차공학회 2014 한국자동차공학회 부문종합 학술대회 Vol.2014 No.5

During the age of fuel economy, aerodynamic efficiency of ground vehicles takes more portion than ever. But aero items, or enablers, are limited because of many reasons. Thus improving the efficiency of current enablers is one of the most important issues to increase aerodynamic performance of the ground vehicles. In this paper, I will discuss about the efficiency of hood deflector. The part can change the whole aerodynamic characteristics of a ground vehicle, both drag and lift, with little change of its shape. Aerodynamic benefit by hood deflector affects drag coefficient reduction. 0.01 drag reduction is generally regarded as 0.2mpg fuel save. Thus by only adding or modifying the hood deflector, more than 1mpg of fuel efficiency can be improved. Furthermore, if the shape of the parts can be optimized, aerodynamic characteristics can be largely changed. To build or optimize 3-Dimensional shape of vehicle, millions of approximated points are needed. But optimizing a number of points is inefficient and almost impossible. So by using improved Vehicle-modeling function, can improve design efficiency for automobiles and other complex systems. Through control poles and various methods of superposition, the complex shape of a large-scale system can be defined by a set of spline curves by Bezier curves. To facilitate shape optimization, methods of shape representation have been widely investigated. As a result, an increase in the number of superposition functions occurs. To resolve this issue, Kulfan and Bussoletti represented the shape information of an object by exponential functions instead of a set of points to control streamline curves, and applied this method to the shapes of 2D wings, 3D wings, and aircraft bodies. For Vehicle Modeling Function for hood deflector, total 10 variables are defined. Using D-optimal DOE method, total 98 cases are defined. The optimized models successfully showed improvement of aerodynamic characteristic of the vehicle. For further study, an optimization tool should be developed to adapt the hood deflector to other kinds of vehicles.

경차의 비대칭 Defrost duct의 HVAC 성능 최적화에 대한 연구

강선제(Sunje Kang),김용년(Yongnyun Kim),송봉하(Bongha Song) 한국자동차공학회 2013 한국자동차공학회 학술대회 및 전시회 Vol.2013 No.11

This paper present a study about developing a defrost performance of the mini vehicle. Defrost performance of vehicle, specially de-ice performance is one of major contributed factor to safe driving on secure vision area view point. Major keys for secure vision area of a windshield are uniformity of airflow pattern at defrost duct outlet. Generally, a mini vehicle has small packaging area to place a HVAC(Heating, Ventilation and Air-Conditioning) module and ducts having symmetrical geometry. There are lots of restriction to develop HVAC module and ducts because of small space. Position and geometry of HVAC module and ducts have negative effect to have uniformity of airflow pattern at defrost duct outlet. For this reason, developing defrost performance in a mini vehicle is required lots of study. This study was performed by CFD CAE to optimize defrost duct design to secure uniformity of defrost duct outlet airflow pattern. Validation results between physical climate chamber test and CFD simulation result are also discussed. Results show well matched for a defrost performance development by CAE.

차체 성능분석 및 최적화를 위한 Deep Neural Network 구축에 관한 연구

김지언(Jieon Kim),김정호(Jungho Kim),송봉하(Bongha Song) 한국자동차공학회 2018 한국자동차공학회 학술대회 및 전시회 Vol.2018 No.11

The Deep Neural Network is a mathematically approximating method of the human brain which consists of neurons network. For this reason, Deep Learning can conduct high complex works such as prediction, classification and making decisions by training data like human. The object of this study is to apply Deep Learning to vehicle body performances analysis and optimization. In Deep Learning method, the most important thing is to define a proper Hyperparameter combination according to each performance characteristic. And it’s not easy to find the best Hyperparameter combination if just depending on engineer’s experience. Therefore, the Hyperparameter optimization procedure using Gradient based optimization method is proposed in this study. On the basis of this method, the best Deep Neural Network prediction model can be built very efficiently with high accuracy and low-cost. This research will be used for large scale optimization cases which were hard to be handled in the past.

반응표면법을 이용한 차량 항력 및 냉각항력의 다중 목적 최적화에 관한 연구

최혜빈(Hyebin Choi),김지언(Jieon Kim),송봉하(Bongha Song),김용석(Yongsuk Kim) 한국자동차공학회 2017 한국자동차공학회 학술대회 및 전시회 Vol.2017 No.11