Design of experiment analysis of air filter performance for helicopter applications

Helicopters are used in different situations and in extremely various environments. Sometimes they land or take off to or from rough landing sites where dust, sand and other materials are present. One of the major problem for helicopters engine is the ingestion of these materials. This problem can be solved by using a filter positioned at the engine intake. The filtration in helicopters is a recent development because, until recent times, research in this field was considered non-profitable and downplayed. Filtration is closely connected with engine efficiency and, in recent years, it has been seen that with a small investiment, helicopter performances were much better. A good filtration means less consumption and more perfomance. This work is a part of a project conducted by BMC Air Filters, a company known worldwide for the production of high performance air filters and air induction systems. The goal of the main project consists in studying the optimization of the process in the design of filter elements for helicopters. The two important features to evaluate an Inlet Barrier Filter are the pressure drop and the capture efficiency. In this work the first aspect is treated. In the engineering design process, the experimentation plays an important role. In this thesis the Design Of Experiment (DOE) method is used to minimize the number of tests conducted, reaching several positive results. Indeed, in order to decrease the pressure loss, the two parameters to change are materials and geometric shape. Thus, two different materials of filter and several different filter geometric shapes are investigated through DOE, leading to identify the best design solution.