Experimental and Numerical Aerodynamic Analysis of a Passenger Car: Influence of the Blockage Ratio on Drag Coefficient

Altinisik, Armagan; Kutukceken, Emre; Umur, Habib

doi:10.1115/1.4030183

Cited by 40 publications

(15 citation statements)

References 19 publications

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“…Skin friction distributions on the pick trucks are shown in Figure 7 where red and blue colors represent attached and detached flows, respectively. Flow separations as indicated in red-shaded color were observed on the surfaces mainly at the intersection of the windscreen and top part of the front section of all models, intersection of cab roof and bed box (except Case 4) and rear end of the bed gate due to approximately zero shear stress caused by adverse pressure gradient as reported in the literature [19]. It is seen that the Case 4 is the best configuration among the models because it contains few areas of blue-shaded colors which mean minimum flow separation.…”

Section: Resultssupporting

confidence: 60%

Numerical investigation of aerodynamic characteristics of generic pickup trucks

Atatug¹,

Bayraktar²

2020

Pamukkale J Eng Sci

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ÖzIn the present study, aerodynamic properties of modified generic pickup trucks were investigated by means of finite volume method. Steady, three-dimensional and turbulent flows over the pickup trucks were solved by standard k-epsilon turbulence model. An experimentally investigated two-dimensional pickup truck found in the open literature was used as a benchmark case and some modifications were done on it by closing the sides of the bed first. Then a tonneau was used to close the top of the box and finally, a canopy was used to cover the box completely from the tailgate to the cab roof. Simulations reveal that such modifications that were done on the reference case improve the aerodynamic characteristics of the vehicles in terms of drag coefficient. With respect to the original case, the drag coefficient reduces approximately 50%, 30% and 20% by using a canopy, a tonneau and closing all sides except top of the bed. Such decreases in drag coefficient was achieved because every modification prevents the flow separation more effectively around the bed and behind the cab. Regardless of the shape of the bed, the drag coefficient decreases with increasing Reynolds (Re) number up to Re=12010 3 . It seems that this is the critical Reynolds number since drag coefficient does not change considerably with Re any more. Bu çalışmada, modifiye edilerek oluşurulmuş kamyonetlerin aerodinamik özellikleri sonlu hacimler metodu ile incelenmiştir. Kamyonetler etrafındaki daimi, üç-boyutlu ve türbülanslı akışlar standart k-epsilon türbülans modeli ile çözülmüştür. Açık literatürde bulunan ve deneysel olarak iki-boyutlu-olarak incelenmiş bir kamyonet referans alınarak, kasası üzerinde bir takım modifikasyonlar yapılmıştır. Bunun için, kasanın yanlarının dışında, üst kısmı da düzlemsel bir yüzeyle örtülmüştür. Son olarak, kasanın üstü, yanlarıyla beraber kamyonet kasasından kabin üst yüzeyine kadar her tarafından tamamen kapatılmıştır. Yapılan simülasyonlar, referans araç üzerinde yapılan değişikliklerin, direnç katsayısı dikkate alındığında, araçların aerodinamik karakteristiklerini iyileştirdiğini ortaya koymuştur. Orijinal duruma nazaran aracın kabinden kasanın üstüne kadar kaplanmasıyla %50, kasanın arka, üst ve yanlarının kapatılmasıyla %30 ve sadece kasanın arka ve yanlarının kapatılıp üst tarafının açık bırakılmasıyla direnç değerinde, %20 düşüş sağlanmıştır. Dirençteki bu azalmaların sebebi, kasa etrafında ve kasa ile kabin arasındaki bölgede akış ayrılmasının önlenmesidir. Kasanın şekli ne olursa olsun, direnç katsayısı Reynolds (Re) sayısının Re=12010 3 'e kadar arttırılmasıyla azalmıştır. Bu değerden sonra direnç değerleri Re sayısıyla artık çok fazla değişmediği için bu değerin kritik Reynolds sayısı olduğu görülmüştür.

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Section: Resultssupporting

confidence: 60%

Numerical investigation of aerodynamic characteristics of generic pickup trucks

Atatug¹,

Bayraktar²

2020

Pamukkale J Eng Sci

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“…It is worth mentioning that this blockage ratio leads to the drag coefficient to be overestimated. According to previous work on a model of Fiat Linea car the drag coefficient was overestimated by 9.2 % for a blockage ratio of 5 % [13].…”

Section: Model Preparation and Meshingmentioning

confidence: 88%

Aerodynamics Assessment Using CFD for a Low Drag Shell Eco-Marathon Car

Abo-Serie¹

2017

Journal of Thermal Engineering

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Having a small car running with low power can be achieved by reducing the aerodynamics drag, rolling resistance and mechanical frictions between the moving parts. The Shell Eco-Marathon competition held around the world with events in Europe, USA and Asia shows every year new techniques and ideas to reduce the power needed to drive the car. The record of over 3400 km on the equivalent of a single litre of fuel is an indication of how car can run efficiently. The problem with these low drag cars is the driver perception about the shape of the car. Although the tear drop shape is known as having the minimum drag, practically this shape cannot be used due to size and packaging limitations in addition to the safety issue. In this work, a low drag concept car is proposed using initial CAD design. The concept car is examined using a commercial CFD software by simulating the airflow around car. The spatial distribution of the pressure and velocity vectors are utilized to improve the car shape and to achieve a low drag force coefficient while keeping the down force at its minimum value. By changing the car front, underneath and rear shapes, it was possible to reduce the drag coefficient from 0.430 for the baseline to 0.127 for the final design, while meeting the competition regulations

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“…However, URANS model provide a very time effective numerical solutions for flow analysis and still a prefer approach in aerodynamic and aeroacoustics industry for large number of numerical simulations without compromising much accuracy. [40][41][42][43][44][45][46][47] Therefore, URANS model is used to simulate 392 configurations. A reference model was made without grooves and drag and lift coefficient results are validated against the study presented by Diasinos et al, 24 with less than 1% deviation.…”

Section: Numerical Configurationmentioning

confidence: 99%

Neural networks assisted computational aero-acoustic analysis of an isolated tire

Uddin

Niazi

Arafat

et al. 2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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The computational aero-acoustic study of an isolated passenger car tire is carried out to understand the effect of dimensions of longitudinal tire grooves and operational parameters (velocity and temperature) on tire noise. The computational fluid dynamics and acoustic models are used to obtain aero-acoustic tire noise at near-field and far-field receivers around the tire and artificial neural networks-based regression are used to study the highly non-linear and interactive causal relationships in the system. Unsteady Reynolds-Averaged Navier-Stokes based realizable k-epsilon model is used to solve the flow field in the computational domain. The Ffowcs Williams and Hawkings model is used to obtain aero-acoustic tire noise at far-field positions. Spectral analysis is used to convert the output time domain to frequency domain and to obtain A-weighted sound pressure level. Artificial neural network–based response surface regression is conducted to understand casual relationships between A-weighted sound pressure level and control variables (Groove depth, Groove width, Temperature and velocity). Maximum A-weighted sound pressure level is observed in the wake region of the tire model. The interaction study indicates that ∼10% reduction in the aero-acoustic emissions is possible by selecting appropriate combinations of groove width and groove depth. The interaction of velocity with width is found to be most significant with respect to A-weighted sound pressure level at all receivers surrounding the tire. The interaction of operational parameters, that is, velocity and temperature are found to be significant with respect to A-weighted sound pressure level at wake and front receivers. Therefore, the regional speed limits and seasonal temperatures need to be considered while designing the tire to achieve minimum aero-acoustic emissions.

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Experimental and Numerical Aerodynamic Analysis of a Passenger Car: Influence of the Blockage Ratio on Drag Coefficient

Cited by 40 publications

References 19 publications

Numerical investigation of aerodynamic characteristics of generic pickup trucks

Numerical investigation of aerodynamic characteristics of generic pickup trucks

Aerodynamics Assessment Using CFD for a Low Drag Shell Eco-Marathon Car

Neural networks assisted computational aero-acoustic analysis of an isolated tire

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