Multi-arm NACA Dimple Golf Ball Aerodynamics
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current golf ball dimple designs fail to effectively induce turbulence in the boundary layer air flow, leading to increased pressure drag, and there is a need for improved dimple geometries that can draw higher energy air into the dimples to enhance aerodynamics.
Innovation Solution
The dimple design incorporates a star-like pattern inspired by NACA duct technology, featuring arms with a leading edge of one width and a trailing edge of greater width, sloped floors, and side walls that create counter-rotating vortices to increase turbulence, with composite dimples arranged in specific patterns on the golf ball surface.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If traditional dimple designs are used, then the golf ball maintains simple geometry, but the boundary layer remains laminar resulting in increased pressure drag
Solution Approach 1:
The dimple is segmented into multiple arms (typically 3-6 arms) radiating from a center point, with each arm containing a NACA duct structure. This segmentation creates multiple vortex generators that collectively induce turbulence more effectively than a single traditional dimple, while maintaining a manageable overall structure that can be manufactured using standard molding techniques.
Solution Approach 2:
The NACA ducts within each arm feature curved, reflex-shaped cross-sections with specific geometric parameters (depth-to-width ratios, angles) that are optimized to generate counter-rotating vortices. The curved geometry of the ducts, rather than straight or angular shapes, is critical for creating the rotational flow patterns that transition the boundary layer from laminar to turbulent.
2Object-affected harmful factors
If dimples are designed to draw in air for turbulence, then pressure drag is reduced, but skin friction drag increases due to turbulent boundary layer
Solution Approach 1:
The dimple design applies turbulence-inducing features (NACA ducts) only in specific locations and orientations around the golf ball surface, rather than uniformly across all dimples. By strategically placing these features in high-flow regions and varying the number of arms per dimple, the design creates localized turbulence where it most effectively reduces pressure drag, while minimizing the overall surface area experiencing high skin friction.
Solution Approach 2:
The design varies key geometric parameters of the dimples including the number of arms (3-6), the depth-to-width ratio of NACA ducts (typically 0.2-0.4), and the angular orientation of arms. These parameter variations allow optimization of the vortex strength and distribution to achieve the right balance between pressure drag reduction and skin friction increase, with different parameter sets suitable for different flight conditions.
3Object-affected harmful factors
If NACA duct geometry is implemented in dimples, then turbulence is induced in boundary layer, but manufacturing precision requirements increase
Solution Approach 1:
The complex NACA duct geometry is created using master molds or master cavities that can be repeatedly used in injection molding or compression molding processes. Once the optimal three-dimensional shape is developed and verified through wind tunnel testing, it is copied many times across the golf ball surface through standard manufacturing processes, ensuring consistent geometry without requiring high precision for each individual dimple during production.
Solution Approach 2:
The NACA duct dimple design serves multiple functions simultaneously: it generates counter-rotating vortices to induce turbulence, creates low-pressure regions to draw in high-energy air from the free stream, and maintains a compact form factor suitable for golf ball applications. This multi-functionality is achieved through the specific reflex cross-sectional geometry of the ducts, which accomplishes several aerodynamic objectives within a single structural feature.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design reduces pressure drag by creating turbulent boundary layers, minimizing wake size and skin friction drag, while maintaining minimal disturbance to airflow, thereby improving the golf ball's aerodynamic performance.
Implementation Method 1
These S-shaped walks are a defining characteristic of the NACA duct and are believed to generate a pair of counter-rotating vortices that efficiently draw higher energy air from outside the boundary layer into the duct
Implementation Method 2
Golf ball dimples work by inducing turbulence in the boundary layer of the air adjacent to the surface of the golf ball
Implementation Method 3
Compared to laminar boundary layers, turbulent boundary layers are better able to remain attached to the ball surface. Thus, the size of the wake behind the golf ball can be reduced if the boundary layer is turbulent rather than laminar
Implementation Method 4
a large proportion of low energy boundary layer air, i.e., the layer of air that clings to the surface or a moving body, is drawn in which reduces the effectiveness of the duct
Data Source
AI summary
A golf ball dimple having a plurality of arms wherein each arm includes a leading edge, a trailing edge, side walls, and a sloped floor. The dimples of the invention may be included in a dimple pattern that may also include other types of dimples.