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The Aerodynamic Development of the New Jaguar XF Adrian Gaylard Technical Specialist – Aerodynamics & CFD

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Overview <ul><li>The Task </li></ul><ul><li>The Process </li></ul><ul><li>The Achievement </li></ul><ul><li>Conclusions </li></ul>

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The Task - The Jaguar S-Type <ul><li>Drag coefficient (C D ) of 0.31, (2.7L diesel variant) </li></ul><ul><li>Lift coefficients of 0.040 (C Lf ) at the front axle and 0.160 (C Lr ) at the rear. </li></ul><ul><li>(Based on a 2.27 m 2 frontal area) </li></ul>

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The Task <ul><li>The first production Jaguar saloon with a C D below 0.3 </li></ul><ul><li>Improved lift distribution between front and rear axles </li></ul><ul><li>Coping with enhanced cooling flows (larger cooling apertures) </li></ul><ul><li>Working with a new style language and other changes </li></ul><ul><ul><li>large haunches </li></ul></ul><ul><ul><li>increased track and overhangs </li></ul></ul><ul><ul><li>bigger wheels </li></ul></ul><ul><ul><li>lower sump and re-designed exhausts. </li></ul></ul><ul><li>An S-Type with these features would have a C D of 0.34. </li></ul><ul><li>0.05 drag task (  C D ) </li></ul>

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The Task - S-Type Aerodynamics

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The Process – Product Development

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The Process – Starting Point

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The Process – Geometry Changes

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The Process – Geometry Changes Before After

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Process – CFD and Correlation

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MIRA Full Scale Wind Tunnel 35 m 2 Closed Jet Process – Full-Scale Wind Tunnels

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Volvo WT 27 m 2 Slotted Wall 200km/h + Moving Belt Rotating Wheels Process – Full-Scale Wind Tunnels

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The Process – Full Scale Testing

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The Process – Full Scale Testing

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The Process – Related Attributes <ul><li>Soiling & Water management </li></ul>Competitor Jaguar XF

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The Achievement – The Jaguar XF

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The Achievement - Drag Relative to S-Type S-Type XF

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The Achievement - Drag Relative to S-Type S-Type XF

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The Achievement - Drag Relative to S-Type S-Type XF

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The Achievement - Underbody

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Conclusions <ul><li>The lowest Jaguar C D so far was delivered with </li></ul><ul><ul><li>About 250 CFD simulations </li></ul></ul><ul><ul><li>Around 600 hours of aerodynamics wind-tunnel testing </li></ul></ul><ul><ul><ul><li>120 hours of moving ground testing. </li></ul></ul></ul><ul><li>No impediment from removing model-scale testing from the process </li></ul><ul><li>CFD in combination with an economical wind-tunnel was effective </li></ul><ul><li>Full Scale Wind-Tunnel testing is essential </li></ul><ul><ul><li>Confirmation of CFD direction </li></ul></ul><ul><ul><li>Better evaluation of aerodynamic lift </li></ul></ul><ul><ul><li>Evaluation of yawed onset flows </li></ul></ul><ul><ul><li>Support for related attributes </li></ul></ul>