Purpose
This paper aims to determine the rational operating regime of a rotary percussive drilling machine under optimal conditions.
Design/methodology/approach
An orthogonal array of Taguchi, signal-to-noise (S/N) ratio, ANOVA Pareto analysis and regression analysis are used to investigate the effect of drilling operational factors on the penetration rate. A series of experiments based on orthogonal arrays L27 was carried out, and the results were collected and analyzed using the statistical software Minitab.
Findings
The statistical analysis (ANOVA Pareto) of the results showed that among all setting parameters, air pressure is the most essential element that affects the penetration rate. The rational operating regime of the rotary percussive drilling machine was determined with optimum air pressure values of 17 bar (Level 3), rotation speed of 60 rpm (Level 3) and a thrust of 825 kgf (Level 2), which maximize the penetration rate. A quadratic regression model was developed for the penetration rate. The predicted values are compared with the experimental data and are considered to be in good agreement.
Originality/value
The study uses the orthogonal array of Taguchi, S/N ratio, ANOVA Pareto analysis and regression analysis to investigate the effect of drilling operational factors on the penetration rate.
This study consists of proposing a new mathematical method to develop a new model for evaluating thermal distributions throughout convergent-divergent channels between non-parallel plane walls in Jeffery Hamel flow. Subsequently, dimensionless equations that govern temperature fields and velocity are numerically tackled via the Runge-Kutta-Fehlberg approach based on the shooting method. Additionally, an analytical study is performed by applying an effective computation technique named Adomian Decomposition Method. Determining the effect of Reynolds and Prandtl numbers on the heat transfer and fluid velocity inside converging/diverging channels can be mentioned as the fundamental purpose of this research. Based on the results obtained for dimensionless velocity and thermal distributions, a supreme match can be observed between numerical and analytical results indicating the adopted ADM method is valid, applicable, and has great precision.
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