Centrifugal pump
Cooling pump for MOTOGP engine
CHALLENGE
A renowned motorcycle manufacturer asked us to study the pump in the engine cooling system of a MOTOGP, in order to improve its performance.
The motorcycle had overheating problems that put its reliability at risk: on a couple of occasions the rider could not finish the race due to engine failure because of too high thermal stress. In addition, the machine had cavitation problems at high RPM.
Our prime suspect was the cooling system: the actual flow rate was clearly not able to remove a sufficient amount of heat from the engine. The sizing of the centrifugal pump, however, seemed sufficient to compensate for the pressure losses at the operating flow rates. We performed some fluid-dynamic simulations of the pump under the correct installation conditions to understand the cause of the problem.
SOLUTION
With the help of targeted CFD analyses, based on validated models, we made the minimum number of modifications in the pump design which were necessary to ensure sufficient cooling capacity and a reduction in the vibrations transmitted to the frame. The resulting increase in engine life has made the bike more reliable, allowing the rider to complete the next Grand Prix races without any problems.
The characteristic curve of the centrifugal pump at maximum rotational speed, 9000 RPM, was obtained by simulating 6 different stationary conditions and was compared with the curve of the cooling circuit.
The CFD simulation at the operating point provided pressure values well below the cavitation pressure in some limited areas of the inlet.
The presence of a 90° curve before the intake was the main reason for the depression: however, it was not possible to modify the geometry of the intake duct, as this modification would have affected the entire engine and transmission design.
We therefore had to improve the design of the impeller and intake duct, in order to minimise the areas subject to cavitation.
RESULTS
After the modifications, we achieved an increase in cooling capacity and a reduction in vibration transmitted to the frame, a sign that the problem of cavitation had been solved. The results were confirmed by both CFD simulations of the centrifugal pump and test rides.
The resulting increase in engine life made the motorbike more reliable, allowing the rider to complete the next Grand Prix races without any problems.
