Your route to this page:
CFD Underhood thermal analysis
of new MINI |
||||
|
During the product definition phase for the new MINI, a complete CAD representation was sent to CD-adapco. Once this had been read into es-uhood, the next task was to produce a closed surface of the geometry read for meshing using the surface wrapping tools. Figure 1 shows the underhood CAD data provided and figure 2 shows the closed surface produced. Next, the fluid mesh was built using an automatic custom mesh to locate increasing levels of refinement around areas of high surface curvature or thin gaps between surfaces. The MINI model totaled 5.5 million cells and featured a detailed underhood area and underfloor region as well as a large external domain. Once the mesh was complete, the model was run at three different conditions to simulate the planned test program. The model included a fan mesh which, in the ‘car at idle’ simulation, was drawing air into the underhood environment. This type of full three-dimensional analysis
is allowing engineers to evaluate particular components
in the MINI’s underhood as follows: |
||||
  |
• The location of the fan and design of its blades could be assessed during the underbonnet installation, something very difficult to do using traditional testing techniques. • Leakage paths around the radiator, which would reduce the radiator’s efficiency, could be identified. This included the redesign of the radiator grill or sealing the flow paths around the radiator. Minor modifications to the model could be easily processed and the model re-run from the previous solution to achieve a rapidly converged new solution. • In the case of the MINI, the major leakage paths around the radiator were identified where high velocity air was moving around the radiator package rather than through it. After this was highlighted, additional sealing strips were added around the radiator pack, and testing proved that there was an improvement in heat release. • As well as investigating the flow through the underhood area under driving conditions, the model could be used to investigate a stationary condition when the vehicle’s fan is operating. This can show a very different flow field from the ones under driving conditions and again highlights areas of reverse flow through the radiator, which will reduce the efficiency of the cooling pack. • In addition to looking at the side effects of airflow in this vehicle, the engine coolant flow could be modeled. This included the crucial heat transfer between air and coolant and made possible the investigation of any area of the radiator not expelling its share of heat. The end tanks of the heat exchangers were also included so that any maldistribution of coolant throughout the matrix would be obvious. The use of es-uhood enables detailed underhood analysis predictions of cars under design. Such high level analysis allows design engineers to understand how particular components will survive in the conditions they will be subjected to during service. It also allows Powertrain engineers to predict the efficiency of a cooling system in an underhood environment. es-uhood continues to demonstrate its powerful capabilities, and CD-adapco looks forward to supporting its clients in the automotive industry as they take up this new technology to get a head start in underhood analysis.
|
|||
That
style icon of the sixties, the Austin MINI, achieved greatness
without the help of CFD. However, its stylistic successor
the new MINI had to be a thoroughly modern car developed
using the latest software tools. CD-adapco welcomed the
opportunity to use its new Expert System CFD tool, es-uhood to
test the car’s underhood cooling performance.