© Mercedes-AMG Petronas Motorsport

Halo with a Down­side

Safety measures like the halo are impor­tant. But they can often have a nega­tive effect on perfor­mance. Not only for racing cars, but for fans as well.

The most striking and contro­ver­sial rule change for the 2018 Formula 1 season – as far as fans and racing teams are concerned – is the cockpit module, called the safety halo. The semi-circular barrier is designed to protect drivers against flying debris. But many are crit­i­cizing the protec­tion system because it disfig­ures the other­wise sporty racing cars. James Allison, the tech­nical director of Mercedes-AMG Petronas Motor­sport, is aware of this. “The imper­a­tive to look after the driver’s safety and our clear desire to give us cars that are going to set the pulse racing aesthet­i­cally will see us continue to develop this concept in the seasons to come.”

Robust – and heavy

The halo is highly robust and must be able to absorb forces of up to 116 kilo­newton coming from various direc­tions. This is why the tita­nium barrier weighs several kilos itself. “We had to strengthen the design of the chassis so that it would roughly take the weight of a London double-decker bus,” explained Allison. This is why it was a true chal­lenge for the team to stay below the weight limit.

Turbu­lence at the tail fin

The halo’s round stan­dard pipe also has a nega­tive effect on racing car aero­dy­namics. Turbu­lence partic­u­larly influ­ences the motor’s air intake at the roll cage and tail fin. The FIA permitted little room for changes in the first season with the halo. “We’re permitted to fit an aero­dy­namic fairing around it,” said Allison. “Which gives us a certain amount of scope to miti­gate the effect it has on the aero­dy­namics of the car.”

Guard grill: the halo for fans

The engi­neers at ebm-papst in Mulfingen are familiar with this opti­miza­tion problem. After all, the end users of fans must ensure that they do not pose a hazard. This is why many fans have a guard grill at the front or back, and in some cases, on both sides.

Bad for effi­ciency and noise

Dr. Jürgen Schöne, Head of Aero­dy­namics at ebm-papst in Mulfingen.

And the safety measures have a nega­tive impact on airflow. “Fric­tion and pres­sure resis­tance are the result,” explained Dr. Jürgen Schöne, head of the Aero­dy­namics Depart­ment at ebm-papst in Mulfingen. “Both resis­tances ensure that fans must consume more power for the same air perfor­mance than they would without a protec­tion system.” But the fan’s noise suffers along with its effi­ciency level.

Reducing losses

The reason for this is that the airflow gener­ated behind the guard grill is distorted. This has its greatest effect on guard grills at the front of fans since the fan blades must rotate through the turbu­lence, gener­ating addi­tional noise at the blades. “The intake side guard grill must be care­fully designed because a lot can go wrong there,” said Schöne. “In recent years, we have focused on devel­oping measures to reduce extra losses and noise. They involve the grill details and blade geom­etry.”

Two birds with one stone: the Flow­Grid

Flow­Grid in sizes 190 to 250 works as guard grille for fans and reduces blade-passing noise by 15 dB at the same time.

ebm-papst provides an espe­cially inno­v­a­tive solu­tion to the problem with the guard grill: the Flow­Grid. Orig­i­nally, the air-inlet guard was devel­oped to mini­mize the effects of turbu­lent airflows that arise inde­pen­dently of safety measures as a result of a heat exchanger, for example. “However, we now use Flow­Grid to imple­ment the safety measures at the same time.” The func­tion does have its limi­ta­tions, though. The Flow­Grid is made of plastic and can only guar­antee the required mechan­ical robust­ness up to size 250.

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