| 摘要 |
A drill bit includes a drill bit body, a cutting member and a fluid course extending in front of the cutting member. The fluid course includes a progressively widening diffuser having a particular design which allows pressure recovery in a fluid flowed through an axial bore of the drill bit body, through a narrow throat of the fluid course in front of the cutting member, and out the progressively widening diffuser of the fluid course. As a result, a significantly reduced pressure is obtained in front of the cutting member, which reduced pressure is below a borehole pressure where the drill bit is used.
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