PSI - Issue 73

Vladimira Michalcova et al. / Procedia Structural Integrity 73 (2025) 106–111 Author name / Structural Integrity Procedia 00 (2025) 000–000

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In the immediate vicinity of the warm wall (1 mm and 2 mm), a larger temperature difference between the beginning and end of the sample is visible in the faster velocity, while in variant 1 the horizontal profile is distributed more evenly.

Fig. 3. u 2 = 2.25 m.s -1 , horizontal temperature profiles above a heated structural element expressed by a dimensionless fraction ∆ � ⁄ . Fig. 4 shows vertical profiles of actual temperatures at the monitored points (point 1-3). In accordance with the horizontal records, they show that already in the space above the beginning of the heated element (point 1) conventional heat transfer is influenced by the air velocity, see detail on the top left. In the first variant the air is heated up (slightly) to a distance of 24 mm above the surface, while in the second variant only up to about 14 mm. In the axis of the structural element (point 2), the air is heated similarly in both variants, up to approximately 35 mm above the surface.

Fig. 4. Vertical temperature profiles above a heated structural element.

Fig. 5 presents the change in the vertical velocity profile above the monitored points. A variant, where the structural element was not heated and had the same temperature as the surrounding air, is also added to these profiles. The assumption that buoyancy forces affect not only the temperature but also the velocity field was confirmed again. While in the first variant the profile "flattens" when it reaches the point 3, at a higher velocity (variant 2) the velocity gradients are uniform at all points. The velocity profile in the case of zero temperature gradient is affected only by friction forces in the boundary layer.