Great emphasis on aerodynamic studies

Columns: On the technical side
Let's discover the interesting news of the KG range, the historic brand of kart accessories, also in light of how aerodynamics are increasingly important in our sport. (F.M.)
Great emphasis on aerodynamic studies

While the debate continues on how the regulation on the issue of bumpers can very often condition or affect race results, the new homologations of the fairings for the two-year period are set. Let’s discover the interesting news of the KG range, the historic brand of kart accessories, also in light of how aerodynamics are increasingly important in our sport as well.
«In the last homologation session we really spent a lot of time and money on this,» explains Davide Gaggianesi. «CFD simulation today has really reached very precise levels. We had the opportunity to have empirical validations on the track with the ‘flow-viz’ (from “flow-visualization” editor’s note) which is a paint containing paraffin, also used in the design of single-seaters; the flow trend and the stagnation points simulated by the software are truly verifiable in real-life case studies. The aerodynamic improvement made with the latest homologation is also aesthetically pleasing, I’d like to say, even if this involves significant production challenges in order to be able to ‘mass’ produce such special parts in series.» In the development of the new fairings, they have stretched and gone beyond what was previously achieved in karting, that is physical tests carried out on the track with Pitot tubes, fundamental in the design of aircraft and probably never used before in karting. In short, the Pitot tube is formed by two air intakes: one tangent to the direction of travel and one perpendicular. The first measures the dynamic pressure, the second the static pressure. One thus works with a differential pressure gauge between static and dynamic pressure. Knowing the pressures determines the speed. «For us, it was interesting to place a pitot tube at the entrance to the duct and one at the exit. This is to go and see how much the duct, thanks to the convergent design, was able to accelerate the flow and therefore to “blow”,» the technical manager of KG continues enthusiastically. «The result is remarkable: at 125 km/h the speed differential is 7 meters per second, over 25 km/h. At higher speed,  the differential increases, but already at 50 km/h as the minimum speed, in a tight hairpin bend, say, the duct is already working well, accelerating by 2 meters per second. This clearly does not mean that the kart gains 25 km/h, but that the flow of air that passes inside the duct accelerates to that speed and is absolutely noteworthy for a vehicle like the kart
Through the use of these tools and in collaboration with Engineering Automotive studies that often arise and collaborate within the Politecnico di Torino, KG has developed the front spoiler 507, in which an attempt has been made to improve the pressure zone of the feet, reducing exposure, improving the flow rate to the radiator and reducing the pressure zone to the tires. At the same time, the range to the radiator and the front brakes (KZ) has been increased, an essential aspect when we talk about these vehicles. These are therefore particularly large number plates which, interpreting the regulations correctly, reach the limit of the ‘possible coverage’ of the foot. Furthermore, the shape or profile of the sides was also influenced by a change of parameters desired by the FIA  for the tensile test, i.e. that one of the various tests requires the pieces to be pulled in the outer part from the bottom upwards with a deformation 100 mm and that the minimum load is now 700 N (previously it was only 450 N). «In the case of the new 507 side pods, on the other hand, the CFD simulations (Computational Fluid Dynamics, ed.) had shown that the opportunities were quite limited and we therefore concentrated on details such as surfaces. The real goal in this sense was weight reduction and it has been achieved: the new side fairing will weigh only 550 g, with a strong weight reduction, including its support with a miniaturization of the brackets too. Dimensions are now minimal, with a 40mm increase in radiator clearance and an increase in the flow of fresh air to the rear wheels. We worked a lot on the materials of both plastic and steel to be able to have good results in terms of crash tests, which have become particularly challenging with such a large reduction in size and therefore in the possibility of energy absorption

THE NEW FRONT PANELS 507 AND 508: OPTIMIZATION OF AIR FLOWS NEVER SEEN BEFORE

«Here we have done two homologations.The 507 model is the basic one, therefore a single much-enveloping fairing surface. However, this “standard” model was not our main focus, but we decided to give the choice between a good product like this at a level commercially in line with our past levels. The real objective, however, was what became the 508 model. For years we have been thinking of creating a venturi duct in front of the driver to accelerate the outflow and diverge part of the outflow from the driver. The regulation requires that the upper part of the “Nassau panel” be at the level of the upper edge of the steering wheel: this is a limit in the pressure on the helmet area, so we thought of a duct that could “blow”, creating a converging shape at the inside of the duct. Tests were carried out to optimize the shape and the first ducts created a whirlwind and stall situation inside the duct itself. At that point in the design, working on the geometries and on the simulation, we tried to have the most laminar and accelerating flow possible.»
 
 

Created by: dmusco - 21/01/22

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