Aerospace applications of precision trepanning

Abstract

In a companion paper “Precision Trepanning with a Fiber Laser”, an analysis was developed leading to criteria for the optimal trepanning of precision holes. Also included were recent fiber laser trepanning test data that nicely verified those calculations. In this paper, we utilize these recent fiber laser trepanning results to show the remarkable economic benefits that could accrue for relevant aerospace applications.Specifically, the jet engine selected for the Joint Strike Fighter (JSF) will require over 1.2 million cooling holes to operate at the elevated temperatures necessary to satisfy current efficiency and fuel consumption specifications. Production drilling of JSF engine film cooling holes will be ongoing for many years.The flow through a small hole is proportional to the fourth power of the diameter. Consequently, a nonlinear equation is developed in this paper to express the normalized flow variance of laser trepanned film cooling holes as a function of the standard deviation in their diameters.Gaussian statistics are then used to determine the likelihood of encountering extreme diameters over a large number of laser trepanned holes. Reducing hole-to-hole film cooling flow variance is important to jet engine manufacturers. This paper shows the substantial economic benefits that can accrue by employing precision trepanning with a fiber laser.In a companion paper “Precision Trepanning with a Fiber Laser”, an analysis was developed leading to criteria for the optimal trepanning of precision holes. Also included were recent fiber laser trepanning test data that nicely verified those calculations. In this paper, we utilize these recent fiber laser trepanning results to show the remarkable economic benefits that could accrue for relevant aerospace applications.Specifically, the jet engine selected for the Joint Strike Fighter (JSF) will require over 1.2 million cooling holes to operate at the elevated temperatures necessary to satisfy current efficiency and fuel consumption specifications. Production drilling of JSF engine film cooling holes will be ongoing for many years.The flow through a small hole is proportional to the fourth power of the diameter. Consequently, a nonlinear equation is developed in this paper to express the normalized flow variance of laser trepanned film cooling holes as a function of the standard deviation in their diameter...