Experimental-Based Correlations for the Characterization of Free Convection of AIr Inside Isosceles Triangular Cavities With Variable Apex Angles

The archival literature contains an abundance of correlations for the characterization of laminar-free convection in rectangular, square, and annular cavities, but unfortunately does not disclose a single correlation for triangular cavities. A prominent application of triangular cavities specialized to isosceles shapes arises in air-filled attic spaces of houses and buildings with sloped roofs and horizontal suspended ceilings. In this work, two contrasting situations are considered embodying three apex angles and several Grashof numbers: a hot base and symmetrically cold inclined sides for winter conditions, and a cold base and symmetrically hot inclined sides for summer conditions. The goal of this article is to construct two dependable correlations, one for the mean convective coefficient at the air/wall interface, and the other for the temperature variation of the ascending air along the center plane of attic spaces. The input data was taken from precise measurements available in the specialized literature.