Product Code: ICAL08_309

Aerospace Applications of Precision Trepanning
Authors:
Paul Jacobs, LFI Inc.; Smithfield RI USA
Presented at ICALEO 2008

In a companion paper Precision Trepanning with a Fiber Laser, analytical constraints were developed leading to criteria for optimal trepanning of very precise holes. That paper also includes recent documented test data verifying these calculations. In this paper, we utilize these optimal fiber laser trepanning results to show the potentially substantial benefits that can accrue for relevant aerospace applications. Specifically, the jet engine selected for the Joint Strike Fighter will require over 1.2 million film cooling holes to operate at the elevated temperatures necessary to satisfy overall efficiency and fuel consumption specifications. Since the flow through a small hole is proportional to the fourth power of the hole diameter, an equation is derived to express the flow variance as a function of the standard deviation in the diameter of the laser trepanned holes, and relevant Gaussian statistics regarding the likelihood of encountering such extremes over a large number of holes. Reducing film cooling flow variance is critical to jet engine manufacturers, and this paper shows the potentially significant benefits that are likely by employing precision trepanning using a fiber laser based system.