Applus IDIADA presents a SUV concept car with a Cx value of 0.19

The concept incorporates two breakthrough aerodynamic innovations to reduce consumption enhanced by an optimized body design

Geneva, 5th March 2018 - Aerodynamics is increasingly crucial in the improvement of electric vehicles’ range. At highway speed a 10% reduction in aerodynamic drag gives a 5% improvement in range. Responding to this need, Applus IDIADA presents at the Geneva International Motor Show 2018, the CRONUZ project, an EV compact SUV concept car with an optimal aerodynamic performance.

The CRONUZ was developed from a blank page to fulfil best-in-class aerodynamic values thanks to the seamless cooperation between Applus IDIADA’s aerodynamicists and designers. That cooperation allowed the upper-body to be optimized while keeping the design concepts. This concept car includes breakthrough aerodynamic solutions that include active and passive aerodynamic enablers that focus on key areas such as the wheelhouses and underbody.

Carles Grasas, CEO of Applus IDIADA declared: “The CRONUZ is the result of a research project that shows that compact electric SUV’s can break the barrier of Cx values below 0.2, while maintaining a streamlined and appealing design.”

Josep Mª Farran, COO of Applus IDIADA added: “This project is another example of IDIADA’s comprehensive engineering capabilities and unique approach that sets the vehicle functionality at the centre of the development process.”

CRONUZ technical specifications:

- Compact electric SUV (C class) 1 electric motor per axle

- 4 seats Lightweight BiW: 200 kg

- Dimensions: 4,415 x 1,819 x 1,536 mm Skateboard battery pack platform: 200L

- Wheelbase: 2,720 mm Closed under-hood with active grill shutter

- Ground clearance: 177 mm Rear view cameras

- Low-friction high-efficiency 195/55/R20 tyres Intelligent light system

Aerodynamics innovations within the CRONUZ Project

Active systems: various rocker and fairings were investigated achieving a potential improvement of 11 drag counts. This force reduction is achieved mainly by reducing forces on the wheels, and increased base pressure via reduced wake intensity. Assuming that the rocker and front fairing could break the design line, we decided to develop active systems for these parts.

Wheelhouse & underbody: The wheelwell areas and underbody are responsible for 40% of the aerodynamic losses and therefore have high potential for improvement. Design actions in this area include optimized rims and underbody wheelhouse covers that interact perfectly with the extended rockers and front fairings to minimize the wheel house air circulation. The effect of the wheelhouse covers and the rims makes a 44 drag count reduction posible.

CRONUZ Design features

The objective of the designing team was to create a minimalist aero design concept to achieve a pure and elegant form with surface and volume solutions to reach a Cx below 0.2. These are the main design features:

- Emotional surfaces

- Streamlined design form

- Steering laser headlamps

- Progressive brightness OLED stop lights

- Dynamics active cooling system/grille

- Driving integrated mirror camera

Final assessment in wind tunnel

The full-scale model was used for testing the vehicle configurations and enablers with better CFD performance, as well as confirming the accuracy of the CFD aerodynamic forces. The best performing vehicle configuration provided a Cx value of 0.19.

Detailed flow measurement in the wake to validate the simulation set-up, including mesh discretization, turbulence modelling and wind tunnel representation were also performed.