Itsariyapinyo, Pititat

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Itsariyapinyo, Pititat
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pititat.it@kmitl.ac.th

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    Characterization of Solar Hot Air Balloons with Different Envelope Shapes
    (2022-01-01)
    Amonjanyaporn, Kritsadis
    ;
    Jiwchuaphan, Patchalaporn
    ;
    Wattanathanakeat, Raschanon
    ;
    Itsariyapinyo, Pititat
    This paper reports on the ground test of the solar hot air balloons which were tethered to the ground station. The measurements of the solar radiation flux throughout the days of testing were carried out using a solar meter to estimate the available heat energy which could be absorbed by the balloons. A temperature sensor was placed at the test site and three thermocouples were installed at an interval of approximately 0.5 m inside the balloon to measure the ambient and internal air temperatures, respectively. A thermal camera was employed to approximate the distributions of the temperature on the balloon surface. The results showed that the solar radiation affects the thermal properties of the solar balloon in two ways. First, the solar radiation and its reflected radiation from the Earth surface directly add heat to the balloon surface. Second, the solar radiation adds heat to the Earth surface and atmosphere and these warm-up Earth surface and atmosphere then add heat to the balloon surface via convection and radiation. Furthermore, the thermal profiles predicted that the tetrahedral balloon could gain heat faster and hence, take flight faster than the spherical balloon when exposed to similar environmental conditions. The spherical balloon, on the other hand, is expected to stay airborne for a longer duration as it is observed to retain heat better than the tetrahedral balloon.
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    Experimental Study of a NACA0015 Circulation Control Airfoil Using Synthetic Jet Actuation
    (2022-01-01)
    Itsariyapinyo, Pititat
    ;
    Sharma, Rajnish N.
    Wind tunnel testing is conducted on a NACA0015 airfoil with a rounded trailing edge, known as a circulation control airfoil, at the chord Reynolds number of 1.10 × 10<sup>5</sup> and at the angles of attack of 0–15°. An array of synthetic jet actuators is installed next to the rounded trailing edge to produce synthetic jet at the excitation frequency range of 150–600 Hz and the momentum coefficient range of 0.00021–0.0134 across the airfoil span length. For the circulation control airfoil at prestall angles of attack, the current study suggested that the reduced excitation frequency of a synthetic jet should approximately be on an order of the Strouhal number based on the diameter of the Coanda surface to achieve optimal lift augmentation.
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    Visualization of the flow behind a backward-facing step using a schlieren technique and tetrafluoroethane
    (2022-11-01)
    Itsariyapinyo, Pititat
    This paper explores the possibility of visualizing the low-speed, near-wall flow using a schlieren imaging technique. In this investigation, wind tunnel testing is conducted on a backward-facing step at step Reynolds numbers of 2940, 5140, and 6120. Tetrafluoroethane is injected through a rectangular slot mounted flush to the wind tunnel floor and is introduced to the downstream region of the step as refractive tracers. The visualization acquired at the midsection suggests that the mass flux of tetrafluoroethane should be approximately 5%-10% lower than that of the freestream air to ensure that the injection is less intrusive to the flow field while still achieving the visibility required to characterize the flow field. For long-exposure photography, the reattachment length or the length scale behind the step can be estimated when the exposure time of a camera is 3.2-12 times longer than the timescale of vortex roll-up. For high-speed photography, the sequence of vortex shedding can be adequately visualized when the frame rate of a camera is at least four times higher than the vortex shedding frequency.
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    Design and Manufacture of Solar Hot Air Balloons with Different Envelope Shapes
    (2022-01-01)
    Korawutwiwat, Kasama
    ;
    Sukchai, Phitchaya
    ;
    Itsariyapinyo, Pititat
    This paper reports on the design and manufacture of the spherical and tetrahedral solar hot air balloons. For the sake of consistency, these two balloons are made of a high-density polyethylene (HDPE) plastic sheet with a thickness of 0.025 mm and are of similar volumes. In this study, the performance of these balloons is mainly assessed by the difference between the internal air temperature of a balloon and the ambient air temperature at a given solar radiation flux range. Three thermocouples are placed at an interval of approximately 0.5 m to measure the internal temperatures of the balloon. In conjunction with these measurements, a thermal camera is used to approximate the distributions of the temperature on the balloon surfaces. The results showed that the effects of solar radiation flux and altitude on the balloon lift force are similar for all envelope shapes and could be approximated with linear functions. Nevertheless, the spherical balloon is expected to be able to carry more payloads than the tetrahedral balloon as it weights less than the tetrahedral balloon of the same volume.