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The use of composite material in modern commercial aircraft has increased significantly in recent years. The very low conductivity relative to Aluminium of composite materials means that the thermal environment experienced in an aircraft, during flight and on the apron, are significantly altered. The heat transfer mechanism is complex: natural and mixed convection flows established in compartments. This paper presents the thermally induced flow structures under representative conditions for a rectangular cavity representative of wing boxes and horizontal tail planes. The paper highlights the sensitivity to boundary conditions, the effect of structural stiffeners. The results indicate it may be possible to incorporate the effect of stringers and heating from above into existing correlations.

Abstract. We describe a heterodyne interferometry system based on a complementary metal-oxide semiconductor digital signal processor ͑CMOS-DSP͒ camera that is utilized for full-field optical phase measurement using a carrier-based phase retrieval algorithm, with no need for electro-mechanical scanning. Camera characterization test results support the adoption of a single-pixel approach to perform quasiinstantaneous differential phase measurements, which are immune to mechanical vibrations and thermal drifts. We developed an optical configuration based on a Mach-Zehnder heterodyne interferometer to perform a static test on a mirror surface. The profiles of the mirror surface set at two angular positions, the relative displacements in the range of nanometers, and the corresponding tilt angle were determined.