General and History of Automotive Aerodynamics

Automotive Aerodynamics 1
GENERAL AND HISTORY OF AUTOMOTIVE AERODYNAMICS
A Research Paper on Aerodynamics By
Rikash Mohamed
Kingston University

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Contents
INTRODUCTION...........................................................................................................................................3
OBJECTIVES..............................................................................................................................................4
HISTORY.......................................................................................................................................................4
Approaches in Early Stages and Shapes...................................................................................................4
Wind Tunnels...........................................................................................................................................8
Car Streamlining......................................................................................................................................9
Change in Drag Coefficient of Cars........................................................................................................10
FEATURES OF AERODYNAMIC VEHICLES....................................................................................................12
Flow Field..............................................................................................................................................13
Improvement of flow.............................................................................................................................15
Characteristics of Flow...........................................................................................................................16
Causes of Drag Force.............................................................................................................................16
Boundary Layer Separation...................................................................................................................17
COMPARISON WITH AIRCRAFT AERODYNAMICS.......................................................................................18
METHODS OF STUDYING AERODYNAMICS................................................................................................20
Wind Tunnel Testing..............................................................................................................................20
Computer Modelling..............................................................................................................................22
CONCLUSION.............................................................................................................................................23
BIBLIOGRAPHY...........................................................................................................................................24

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INTRODUCTION
This research paper is about the general and history of automotive aerodynamics and majorly
focuses of the approaches in early stages and shapes, wind tunnels, car streamlining, change of
drag coefficient of cars, features of aerodynamic vehicle such as boundary layer separation,
causes of drag force, characteristics of flow, improvement of flow, as well as flow field and also
comparison with aircraft aerodynamics. Aerodynamics involves the study of air motion,
specifically as interaction with a solid object like automotive. Automotive aerodynamics can be
defined as the study of the road vehicles aerodynamic. The major objectives of studying
aerodynamics of vehicles are to prevent aerodynamic instability at high speed and undesired lift
forced, minimize noise emission, wind noise, and reduce drag.
It first began as a way to determine methods of reducing the required power to move the
automotive at a specific speed on the roadways. In the year 1920s, engineers started considering
the shape of automobiles as a way of minimizing aerodynamic drag at a high velocity. In the
1950s, British and German automotive engineers were examining the impacts of automotive
friction for vehicles of high performance. They became conscious of the substantial increase in
the levels of sound produced by automotive at high speed by the late 1960s. Soon the highway
engineers started designing roadways to contemplate the speed effect of aerodynamic friction
generated levels of sound and the manufactures of these automobiles considered the same factors
in the design of the vehicles. Currently, numerous automakers have their own facilities for
testing wind tunnel, using it in developing and studying the aerodynamic features of any new
automotive (Ainegren & Jonsson, 2018).

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OBJECTIVES
The main objectives of this research paper on the general and history of automotive
aerodynamics are:
 To analyze the approaches in the early stages and shapes of automotive
 To evaluate the features of aerodynamics
 To compare aerodynamics with aircraft aerodynamics
 To determine the method of studying aerodynamics (Alam, et al., 2012)
HISTORY
The aerodynamic drag caused by the frictional force significantly increases with the speed of the
vehicle. In the early 1920s, engineers stated considering the shape of an automobile so as to
minimize aerodynamic friction at high velocity. By the year 1950s, British and German
automotive engineers were examining systematically the impacts of automotive friction for the
vehicles of higher performance. Engineers also became conscious of the substantial increase in
the levels of sound produced at high speed by the vehicles by the late 1960s (Antanaitis, 2012).
Approaches in Early Stages and Shapes
The air presented the greatest obstacle to the economy and automotive speed and this was
intuitively and scientifically understood before the dawn of automotive. Entrepreneurs, racers,
engineers, and dreamers were lured by the potential for the aerodynamic offered and profound
gains. The efforts to do resulted in more remarkable vehicles even if they challenged the
aesthetic assumptions of their moments. The origins of streamlining go back to 200 years ago
and the ideal form of streamline was illustrated by Sir George Cayley in 1865. Racers,
specifically those chasing the coveted and Speed Record were normally the first to apply the aids

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of aerodynamics (Antanaitis, 2016). The first automobile to break the 100km record in 1899 was
Jamais Contente shown in the figure below:
Figure 1: Jamais Contente of 1899 (Bansal & Sharma, 2014)
The position of the driver seems to reduce the aids of aerodynamics. The aerodynamic evolution
for the land speed record cars was rapidly remarkable as evidently shown in 1906 by Stanley
Rocket. The increased velocity was also even dramatic since the Rocket broke the barrier if
200km with a run of 205.44 kmh.
Figure 2: Stanley Rocket of 1906 (Buljac & Džijan, 2016)

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The first known attempt at streamlining a passenger vehicle was in 1914 in the Alfa Romeo
which was built for the Italian Count Ricotti by the coachbuilder Castagna. This vehicle turned
out not to improve the maximum velocity of the open Alfa due to the very heavy bodywork it
possessed (Chandar & Damodaran, 2010).
Figure 3: Alfa streamliner of 1941 (Chen, 2014)
The actual success of aerodynamic passenger vehicle was the German Rumpler of 1921. Unlike
the heavy and impractical Castagna Alfa, this vehicle was influential and different dynamically
due to its complete integration and original engineering and design. This car had numerous
features such as a four-wheel independently suspended by the use of swing axles and also a mid-
engined W6 engine. The German Rumpler was tested in a wind tunnel of VW in 1979 and
attained a Coefficient of drag of .28 remarkably. This degree of Coefficient of drag was later
attained by the Passat in 1988. The Coefficient of drag of a body denotes the relative
aerodynamic slipperiness of the vehicle irrespective of its entire size. The cross-section of the
vehicle looking straight on is multiplied by the Coefficient of drag to attain the critical total
aerodynamic drag which determines efficiency and the power required. The German Rumpler
was very aerodynamic relatively, however, it was quite boxy and tall, which led to numerous of
such designs to be used basically as taxis (Dalessio & Duncan, 2017).