Two Streamwise Drops Impinging onto a Plate

  • 陳 盛旗

Student thesis: Master's Thesis

Abstract

An experimental investigation is performed into the impact characteristics of two streamwise drops impinging on a plate The drops are generated using a free-falling drop technique and a drop severance device The experiments are performed using water as the working fluid and a drop velocity of 1 9 ± 0 1 m/s The experiments have focused particularly on the effects of the initial drop diameter (di) and oblique angle (Φ) of the impinged surface on the impact phenomena The investigation considers four different impingement conditions differentiated by the different time intervals (Δt) namely Case 1: single drop impingement; Case 2: Δt = Δt1 (the leading drop starting spreading); Case 3: Δt = Δt2 (the leading drop reaching its maximum spreading); and Case 4: Δt =Δt3 (the leading drop reaching its maximum height) Notably all of the cases correspond to low Weber number impingement (We = 40 ~ 50) It is shown that for the two drop impingement cases (Cases 2 ~ 4) the maximum spreading diameter is around 1 3 times larger than that of the single drop impingement case (Case 1) given the same initial drop diameter and a horizontal flat surface (i e Φ = 0°) Moreover the impact characteristics for an initial drop size of 1025 μm are similar to those for an initial drop size of 930 μm For a given initial drop diameter the spreading diameter (dw) decreases as the oblique angle increases from Φ = 0° ~ 15° However for Φ = 30° the spreading diameter increases compared to that for Φ = 15° As the oblique angle is further increased to 45° the spreading diameter reaches its maximum value and stabilizes For a given initial drop diameter the maximum film height is obtained in the Case 3 impingement condition for all of the considered oblique angles (Φ = 15 30 and 45°) As the oblique angles increasing the steady height of the drop decreases
Date of Award2017 Jul 28
Original languageEnglish
SupervisorTa-Hui Lin (Supervisor)

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