Geo-Drill: Novel DTH hammer

The new DTH fluid hammer designed and built by Fraunhofer IEG within the Geo-Drill project will operate with an innovative piston control system, providing a more durable and longer-lasting performance of the whole percussion device. Commonly used mechanical valves in such a percussion system will be substituted by a fluidic oscillator without any moving parts, which operates based on the Coandă effect and will be much less vulnerable to wear.

Based on IEG´s iterative approach of numerous experiments and numerical simulations, this built-for-purpose fluidic oscillator has been developed, showing improved performance to already known and reported designs from literature. IEG´s newly developed fluidic oscillator allows frequencies well within the range for today’s DTH hammer drilling applications. Most important, the stability of this Coandă effect based internal flow behavior and regime has been enhanced drastically, resulting in reliable starting and controlling of the connected percussion mechanism.

Furthermore, IEG´s percussion mechanism shows several advantages compared to other industry standard and state-of-art mechanisms, e.g. process reliability, less water consumption for the generated power output, well suitable frequency range and a rather compact design.

In combination with this optimized fluidic switch, IEG then developed a complete, tailored percussion unit providing new possibilities and more reliability for deep hole DTH drilling applications

Article Courtesy: Fraunhofer IEG