F0riction losses in coolant flow through kidney shaped gundrill shank

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Abstract
The factor of factional losses for both laminar and turbulent coolant flow through the passages in a gundrill has been investigated. A kidney shaped passage in the tip has been used because it is superior to both single circular and double circular passages. An extensive experimental investigation revealed a considerable deviation from the Blasius relation for circular passages. The concept of hydraulic diameter used to predict friction in circular passages fails to predict the friction in the kidney shaped passage. The results of this investigation suggest that by introducing a concept of a characteristic dimension of the passage cross-section, the friction can be predicted in a relatively simple manner similar to the Blasius approach. Computer fitting of the experimental data resulted in an empirical relation which can be used to calculate the factor of frictional tosses in a kidney shaped gundrill passage for coolant.