Motorsport: Aerodynamic Development
Experimental vs Computational methods
As in any engineering discipline, it’s important to use the right tools for the job. Aerodynamic development in motorsport is no different. In Formula 1, experimental methods have dominated motorsport aerodynamic development – predominantly with wind tunnel testing of scale models. The costs of such a programme are high however: requiring a highly detailed and accurate scale representation of the race car, and significant time in an appropriate wind tunnel.
Increasingly over the past 15 years wind tunnel testing has been supplemented with computational methods - Computation Fluid Dynamics (CFD). Using powerful computers to perform numerical analysis calculations, it’s possible to simulate the air flow that interacts with a vehicle's surfaces. In more recent times, with the exponential growth of the super-computer, CFD has become far more prevalent, and in Formula 1 has now become the principle development tool. It has also opened a development method for other motorsport disciplines, without perhaps the need for expensive wind tunnel testing.
I’ve been fortunate enough to witness the rise of CFD first-hand, and to view and appreciate the benefits that it offers. The computation predictions produce a wealth of knowledge and information in helping to understand the flow fields around a vehicle. I’ve been a great advocate for the use of CFD throughout my career in motorsport, but I’d also like to question whether its use is fundamental in every circumstance. Computational methods are the new tech and the future of aerodynamic development, but are they the right tool for all scenarios?
Formula 1 is like no other motorsport. The level of financial commitment is unparalleled in any other motorsport discipline. Although CFD is perceived to be the “cheap” alternative to wind tunnel testing, to achieve its true worth still requires some significant investment. To achieve reasonably development progress generally requires very high-fidelity models, and significant numbers of cases and conditions to be solved – which are typically time and labour intensive. There also remains some questions over the real-world accuracy of CFD. CFD has revolutionised the development process (in F1 at least) with increased flow understanding. In terms of aerodynamic load predictions, it is not without inaccuracies, but generally good for identifying trends. Predictions of the flow in turbulent regimes is an area of concern, due to the instabilities that occur. Flow around the tyres for instance are typically difficult to predict correctly. In my experience, CFD has also been notoriously difficult to predict drag force, again due to the turbulent nature of the flow. Given sufficiently high model fidelity, number of cases and permutations, then a fuller understanding of the flow can be gleamed. This works extremely well in F1, where an aerodynamics department can typically have dozens of engineers dedicated to this exercise, and financial concerns are less of an issue.
But is this also true of other motorsport disciplines? For instance, how about a LMP, GT, or BTCC manufacturer/team with a vehicle already in competition – what is the best tool(s) for improving the aerodynamic performance?
In these scenarios, cost is obviously a big factor. Scale model testing is a significant commitment and investment, likely reserved for long term development programmes. There are certainly computational options for these scenarios, but they are not necessarily the best option when considering the above comments. It’s certainly possible to scan an existing vehicle easily and complete some initial CFD studies without significant cost. However, I believe that wind tunnel testing is still a valid and potentially cost-efficient option to improve performance – but full-scale testing using the existing race vehicle. Full-scale wind tunnel testing can be an excellent tool to categorise a vehicle’s aerodynamic performance, optimise it’s configuration/setup, and provide directions for future performance gains. This cost of renting a full-scale wind tunnel is not as significate as you’d think, and the returns are far more yielding in the real world. The biggest benefit is that the subject matter already exists and ready to work with, which is significant in terms of development timescales. The downside is the availability of facilities for such testing, which are limited. However, there a few options, and some even in the UK.
From my experience, an ideal development programme for these scenarios would involve some limited CFD knowledge to feed into a full-scale wind tunnel test session(s). This can be a cost-effective method for improved aerodynamic performance, without the need for huge investment or commitment.
Dynamic-Aero can offer and arrange these services and provide professional expert advice on aerodynamic development programmes.
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