Effect of Bulkhead Pressurization on the Vibro-Acoustic Properties of an Aft-Fuselage-Mounted Twin-Engine Aircraft

Abstract Despite widespread use of an aft-fuselage-mounted twin-engine aircraft in the business jet industry, a thorough investigation into the vibro-acoustic properties of this aircraft type has yet to be undertaken. Additionally, the effect of bulkhead pressurization on the vibro-acoustic properties of this aircraft fuselage has yet to be investigated in isolation. This work investigates the effect of bulkhead pressurization on two different designs of an aft-fuselage-mounted twin-engine aircraft: a single and a double bulkhead designs. A modal analysis, a harmonic frequency response analysis, and an acoustic response analysis were performed. A split bulkhead pressurization methodology was introduced as a means of improving structural performance without impacting passenger comfort levels in a double bulkhead aircraft. Modal coupling between components was seen to be the primary cause of increased cabin noise, peaking above 80 Hz. The bulkhead frequency response was highly dependent upon bulkhead pressurization, as the modal participation factors were significantly impacted by bulkhead pressurization. Therefore, the importance of understanding all bulkhead natural frequencies was highlighted, as the response changed as a function of bulkhead pressurization. Bulkhead resonance conditions generated a tone in the acoustic frequency response inside the passenger cabin, highlighting the importance of this component to passenger comfort levels.