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Develoment of Droplet Velocimetry Method Using Shadowgrapy

Abbasi Zarrin, Fatemeh | 2018

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  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 50950 (45)
  4. University: Sharif University of Technology
  5. Department: Aerospace Engineering
  6. Advisor(s): Kebriaee, Azadeh
  7. Abstract:
  8. Injection of liquid fuel in the cross-flowing air provides a means of higher penetration, rapid mixing of liquid fuel and air, and is encountered in many engineering applications. Air-breathing propulsion systems (e.g. gas turbine combustors, ramjets, and scramjets), liquid rocket engines,cooling sprays for turbine blades, and injection of fuel in the afterburners are examples of such applications. The identification of microscopic characteristics is one of the basic methods of atomizer examination, which has not been taken into account due to inadequate experimental equipment. In the present study, droplet mono-frame velocimetry and size distribution of secondary atomization in a pressure atomizer with slot cross section have been conducted. Light emitting diodes are utilized as a pulsed light source which is set in an inline arrangement with the test section and the camera. As a result, the droplet shadow forms a dark spot on a bright background. A novel method is employed for velocimetry such that two Consecutive images of the droplet motion are recorded on the same frame by using two sequential pulses of the light source. Then, using a self-developed computer algorithm, each droplet and the respective pair in the same image, is detected, the velocity vector is obtained, and the results are discussed.For the sizing of spray droplets, the light source is set to single pulse mode, then the images are processed and calibration procedure is applied to extract the final size distribution. The most basic method of presenting in the literature is utilized for particle sizing. Eventually, the droplet velocimetry and sizing methods are examined for the evaluation of microscopic characteristics of slot atomizer in cross flow for different Weber numbers and momentum ratios
  9. Keywords:
  10. Spray ; Cross Flow ; Shadowgraphy Method ; Droplet Size Measurment ; Mono-Frame Technique ; Velocimetry

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