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GEO-DRILL DTH Fluid Hammer

Tue, 22 September, 2020

The Geo-Drill Down-The-Hole (DTH) fluid hammer will operate with an innovative valve system, providing a more durable and longer lasting performance of the whole device. The commonly needed valve in such a percussion system will be substituted by a Coandă based fluidic oscillator without any moving parts and, therefore, be much less vulnerable to wear.

The fluidic switch (as shown in the figure) consists of one inlet port (1) and two outlet ports (5), which are connected to the respective upper and lower chambers of the percussion system, which includes an oscillating piston within a cylinder. The fluid follows along the inner surface of the mixing chamber (2) to one of the two outlet ports due to the Coanda effect. The feedback loops (3) will cause fluid flow inside the switch to alternate between the outlet ports, once a chamber is filled. A full chamber will be emptied through one of the outlet vents (4).

The initial prototyping is done via 3D printing for quick adaption and variation of parameters. E.g., surface roughness has become rather smooth down to 24 µm, appr. 10 times less than a sand´s grain diameter, while the printing structure remains regular and of high quality. A smooth surface is vital for safe functioning of the mixing chamber, as the Coanda effect only works with laminar flow across a smooth surface.

Geo-Drill will thereby be able to develop a completely new way of DTH drilling, and providing a more reliable device for deep hole drilling applications.

Article courtesy:

IEG Fraunhofer (Germany)

Fluidic switch CAD model (left) 3D printed prototype
Fluidic switch CAD model (left) 3D printed prototype