Client: Baruffi Composites Solutions
Contact person: Eng. Davide Mavillonio, Eng. Yauheni Parfionau
Category: Fluid Dynamics, CFD Analysis
Requirement
Baruffi Composites Solutions, a leading company in the design, development and production of both aesthetic and structural products in advanced composite materials for many sectors, and in particular for the automotive one, has relied on the experience of Asotech to test the longitudinal stability characteristics of a motorboat of its realization for the inshore motorboat championship.
An innovative high-performance boat that presented some salient features compared to other boats, such as floating elements and a flat bottom with futuristic geometries, designed to increase the efficiency of navigation, and a lighter and more resistant pilot survival cell that, combined with the use of carbon materials, allowed weight savings and a consequent gain in top speed.
Baruffi Composites Solutions used Asotech’s expertise to test two critical aspects of the vessel prior to its actual testing:
Aerodynamic lift
Lengthwise stability
Lift and drag play a fundamental role in the calculation of powerboat performance, since aero and hydrodynamic characteristics but also longitudinal stability depend on them.
To perform the CFD numerical simulations, Asotech professionals used the commercial program FLUENT in ANSYS Workbench 2019 R1 environment with the appropriate modules for the pre-processing, solving and post-processing phase. Once simplified the 3D model provided by the client in Space Claim environment, the fluid dynamic model has been created, which has allowed to understand the trend of air and water flows and how lift and drag forces change with the variation of the inclination and speed of the vessel. In fact, a number of cases have been examined with different boat inclinations (from 0° to 12°) and speeds (from 0 to 200 km/h).
Given the impossibility of obtaining information regarding the engine thrust, it was decided to simulate the propeller in its maximum efficiency conditions. As for the vessel, the propeller model was imported into the Space Claim environment and then into Fluent to obtain the thrust curves as the pitch angle and rotation speed varied.
Once analyzed the data obtained, it was possible to detect that the boat had some defects, in particular a rear downforce, which led it to be particularly unstable and with a tendency to overturn.
Essentially, the main objective was to obtain the negative pitch moment characterized by the location of the center of pressures behind the CG.
On the motorboat there were also some areas of partial detachment of the fluid vein (see figure below): their presence would have led to a loss of efficiency of the vessel and a consequent reduction of the maximum speed attainable.
Thanks to the collaboration with Asotech, Baruffi Composites Solutions has obtained a boat that will allow to compete in complete safety in the inshore powerboat championship.
The suggested modifications, derived from a scrupulous CFD analysis, have allowed to obtain a 30% higher lift and a 5% increase in performance, in terms of speed and lower consumption, compared to the competitors’ models.
