Armed with CFD tools, the golf club maker applies aerodynamic principles to driver design, pushing the boundaries of range and performance.

A few years back, when most golf club manufacturers were fixated on building bigger drivers with broader heads, the engineering team at Adams Golf had a different approach in its sights. Unlike competitors who viewed larger head size as the key to longer distance and better performance, the Adams team believed that bigger clubs caused drag that hindered even the best players’ swings. Armed with computational fluid dynamics (CFD) simulation software and applying aerodynamic principles to golf club design for the first time, the team began a journey that would culminate in a driver concept that pushed the boundaries of range and performance without adding unnecessary weight and materials overhead to the club’s design.

The industry’s obsession with making bigger and wider-faced driver heads began in the late 1990s. Thanks to an influx of R&D dollars, golf club manufacturers got more adept at utilizing materials such as titanium as well as leveraging design tools such as mechanical computer-aided design (MCAD) to push the limits of technology and create new “extreme dimension” club shapes. Although the United States Golf Association (USGA) traditionally had no limit on club size, it recently imposed limits on club head volume (460 cc), moment of inertia (MOI), and dimension. Those rulings inspired an influx of unusual club shapes, all trying to leverage size to achieve greater swing distance. On the heels of a raft of studies conducted in the mid-1990s that found that aerodynamic drag was not large enough to have a negative impact on swing speed, most golf club manufacturers had sidelined aerodynamics as a key design factor when architecting their next-generation drivers.

The prevailing industry wisdom did not sit well with the engineering team at Adams Golf. In player tests and confirmed by observations on the Professional Golfers’ Association (PGA) tour, Adams engineers discovered that golfers using the extreme size clubs designed near the new USGA limits were getting slower club head speeds and experiencing diminished driving distances. On the basis of those informal observations, the team circled back to the issue of aerodynamics. The extreme shape of the new club genre made the drag issue relevant, the team surmised, because the heads had become so large and poorly shaped from an aerodynamic point of view that the aerodynamic drag force had become significant. With this hypothesis in mind, the Adams team set out to put new tools and processes in place to account for aerodynamic design principles even though it was relatively unproven ground in golf club design.

Integrated CAD and CFD

For its first pass at aerodynamics, Adams brought in outside consulting help that had a specialty in CFD since the company lacked that kind of formal expertise in house. The consultants were able to identify areas of concern on the driver where drag was an issue: on the top of club crown, for example, and on the heel and toe side of the club. This education in airflow paved the way for a trio of prototypes that were built and trialed in wind tunnel and player tests. That process narrowed the field to one low-drag design: the Speedline driver, which was manufactured and brought to market in January 2009. The Speedline won critical industry acclaim and put Adams on the map as a leading driver manufacturer for the first time.

After the success of the Speedline, Adams engineers knew there was an opportunity for refinements that would achieve more dramatic results. Yet enlisting the outside CFD specialist was too costly on an ongoing basis and did not allow Adams to iterate design trade-offs in a timely or consistent manner. The team realized that it needed to bring the CFD process in-house to capitalize on its potential fully, yet it needed a solution that would be accessible to Adams engineers, who had no formal training in CFD let alone familiarity with a specialized, best-of-breed tool set.

The answer came by way of leveraging an MCAD solution that had integrated CFD functionality, in this case, Siemens PLM Software’s NX tool and Flow CFD module. Today, instead of sending out CAD design files for analysis and limiting the field to a handful of possible new designs, the Adams team is able to examine airflow over proposed 3-D models in real time, making modifications and refinements to the club design as it sees fit without having to build costly prototypes or design tooling. An integrated CFD tool also highlights possible problem areas in easily understood color codes; this is much easier for non-CFD experts to visualize than cryptic drag and lift data generated by wind tunnel testing.

Although the integrated CAD/CFD tool was an enabler that allowed Adams engineers to take on the aerodynamics challenge on their own, it quickly became apparent that the outside CFD specialists still had an important role in the product development loop. Because of the lack of internal domain expertise on the Adams side, the CFD specialists are tapped to provide direction and verify CFD simulation results. The outside consultants are also instrumental in setting up the proper tests in the wind tunnel, helping the Adams engineers evaluate competitors’ clubs for which there is no access to CAD models. In addition to the intermittent consulting help, the Adams team has established standard operating procedures for its CFD and aerodynamics work to ensure that all six engineers on the team are setting up files in the same manner and, most important, getting consistent simulation results.

Aerodynamics Design Factors

The Adams team has had notable success thanks to the integration of CAD and CFD. In addition to the well-received Speedline driver, the team put its new tools and development processes in place for follow-on drivers that pushed the drag issue even farther. Whereas the initial Speedline driver had a reduced face area on the club to achieve less aerodynamic drag, the Adams team was able to increase that space on subsequent models, improving impact efficiency while delivering even higher club speeds. Specifically, the Speedline FAST 10, released this past January, has an expanded face size but achieves a 10% reduction in drag, allowing for a faster club head speed that produces an extra 10 yards of carry distance. The team was able to achieve that ratio by using the integrated CAD and CFD environment to simulate the different orientations of the club head as it moves through the swing. By testing multiple iterations in this manner, the engineers were able to make subtle modifications to the face area in addition to transition areas from the face to the club’s body.

Having an integrated CAD and CFD environment also has affected Adams Golf’s ability to get designs to market faster. Traditionally, the team would originate a driver design concept and send it to China to be manufactured, a process that could take 30 to 60 days. The parts would be physically tested and verified, and if changes were made, the production window would begin again. The CFD consulting used in the original Speedline development project shortened the time required to evaluate a design that cycle to around 20 to 40 days, but the integrated CAD and CFD tool approach brings the process down to less than a few days.

Although competitors have followed suit and begun designing clubs around aerodynamic principles, Adams has a one-year lead. The team has created a portfolio of intellectual property around aerodynamic designs and successfully refined its do-it-yourself CFD process in the hopes of maintaining its lead.

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