Loading...

Investigation of the Effect of Shape, Frequency and Amplitude on Fin Oscillating Motion Inspired by Fish Tail Shape

Raiszadeh Oskooi, Mohammad | 2021

332 Viewed
  1. Type of Document: M.Sc. Thesis
  2. Language: Farsi
  3. Document No: 53908 (08)
  4. University: Sharif University of Technology
  5. Department: Mechanical Engineering
  6. Advisor(s): Vossoughi, Gholamreza; Seif, Mohammad Saeed
  7. Abstract:
  8. Inspired by the behavior of creatures in nature, including fish, generating propulsive forces under water has attracted great interest in recent years. Various tools such as computer software and experimental laboratory observations can be used to study the movements for different types of fishes. In this research, two thin fins, the shape of which is inspired by fish tail, will be investigated as a simplified model under non-viscous and incompressible fluid conditions using the experimental results and Ansys CFX software. For this purpose, the fin is considered once as a unforked rigid cantilever and again as a rigid forked cantilever with a constant water inlet speed of 10 cm per second. Next, using equations of motion, fluid pressure distribution on the fin surface are calculated and movement speed and energy consumption are obtained. This is performed for each fin at two different frequencies and amplitudes. For the experimental work, fins and movement conditions are duplicated as in the numerical analysis. The thrust forces generated are then measured under the periodic movement of the fins. The results are then compared with the the numerical analysis results to validate the numerical results. Experimental results are then analyzed based on statistical methods. After validation, in CFX software, the shape of the created vortices and various other parameters such as power factor, thrust coefficient, work done and displacement coefficient of these movements are compared. Based on the results, the coefficient of power and work done in the fork fin is less than unfork fin. In fact, the fork fin performs better with regard to these two parameters. While the unfork fin is more suitable in terms of displacement coefficient. By decreasing the oscillation frequency, the amount of power factor, the work done and the displacement coefficient are reduced. Also, the amount of drift coefficient decreases with decreasing amplitude. In some other cases, the process may be different for each fin. For example, as the amplitude of the oscillation decreases, the power factor for the unfork fin decreases; while for forked fins this had an upward trend. Based on the results, it is not possible to say with certainty, which fin and movement results in a better performance. That is, one mode may be best in one parameter and not very suitable in another. Based the desired goal, one of the parameters should be taken as the objective function and then the best fin shape and oscillating frequency and amplitude should be selected
  9. Keywords:
  10. Fin Actuator ; Amplitude ; Frequencies ; Fish Locomotion ; ANSYS Software ; Fish Tail ; Experimental Investigation

 Digital Object List

 Bookmark

No TOC