Date of Award
5-2025
Document Type
Thesis
Degree Name
Master of Science in Mechanical Engineering (MSME)
Department
Mechanical and Aerospace Engineering
First Advisor
Saeed Al Nuaimi
Second Advisor
Mohamed Kamra
Abstract
Energy harvesting from ambient sources has gained attention due to increasing energy demands. Despite VIV-based harvesters showing significant potential, their lock-in region, where significant power is generated, is narrow. Given the continuously varying ambient conditions of fluid currents, harvesters can easily fall into de-synchronization, yielding low energy output. Existing solutions like tunable masses or multiple degrees of freedom systems increase complexity and weight, limiting practical applications. This work introduces a novel variable diameter cylinder mechanism—a practical technique that actively tunes the cylinder’s geometry in real time to enhance energy harvesting efficiency from VIV. The mechanism employs an expanding pulley system that deforms the elastic circular cylinder radially, dynamically altering its diameter to adjust key non-dimensional parameters governing VIV. This real-time adaptability counteracts ambient fluctuations, significantly widening the lock-in range. The cylinder incorporates a piezoelectric transducer, and the fluid-structure-piezoelectric interaction problem was analyzed numerically to determine the cylinder motion, voltage, and power output. A partitioned Lagrange-Eulerian approach was employed, coupling an FVM fluid solver with a custom-coded structural piezoelectric solver via the preCICE library which enables data mapping and exchange between solvers at run time. The analysis was conducted for different diameter profiles, and the results showed an enhancement in the harvester synchronization width and maximum amplitude by 70% and 117%, respectively, compared to the constant diameter case. Additionally, a 113% increase in peak voltage was achieved, and more than 8 times greater power was generated. The analysis also showed the effect of load resistance on harvesting performance, and the varying diameter cases demonstrated resilience against the shunt-damping effect. The proposed control technique is versatile, as it can be used for VIV suppression as well as energy harvesting applications.
Arabic Abstract
اﻟﺤﺼﺎد اﻟﻄﺎﻗﻲ واﺳﻊ اﻟﻨﻄﺎق ﻣﻦ اﻻھﺘﺰازات اﻟﻨﺎﺗﺠﺔ ﻋﻦ اﻟﺪواﻣﺎت ﻷﺳﻄﻮاﻧﺔ ﻗﺎﺑﻠﺔ ﻟﻠﺘﺸﻜّﻞ
اﻛﺘﺴﺐ ﺣﺼﺎد اﻟﻄﺎﻗﺔ ﻣﻦ اﻟﻤﺼﺎدر اﻟﺒﯿﺌﯿﺔ اھﺘﻤﺎﻣًﺎ ﻣﺘﺰاﯾﺪًا ﻧﺘﯿﺠﺔ ﺗﺰاﯾﺪ اﻟﻄﻠﺐ ﻋﻠﻰ اﻟﻄﺎﻗﺔ. وﻋﻠﻰ اﻟﺮﻏﻢ ﻣﻦ أن أﻧﻈﻤﺔ اﻟﺤﺼﺎد اﻟﻤﻌﺘﻤﺪة ﻋﻠﻰ اﻻھﺘﺰازات اﻟﻨﺎﺗﺠﺔ ﻋﻦ اﻟﺪواﻣﺎت (VIV) ﺗُﻈﮭﺮ إﻣﻜﺎﻧﯿﺎت ﻛﺒﯿﺮة، إﻻ أن ﻧﻄﺎق اﻻرﺗﺒﺎط – (lock in)، اﻟﺬي ﯾﺘﻢ ﻓﯿﮫ ﺗﻮﻟﯿﺪ ﻗﺪر ﻛﺒﯿﺮ ﻣﻦ اﻟﻄﺎﻗﺔ، ﯾﻈﻞ ﺿﯿﻘًﺎ. وﺑﺎﻟﻨﻈﺮ إﻟﻰ اﻟﺘﻐﯿﺮ اﻟﻤﺴﺘﻤﺮ ﻓﻲ ظﺮوف اﻟﺠﺮﯾﺎن اﻟﻤﺤﯿﻂ، ﻓﺈن ھﺬه اﻷﻧﻈﻤﺔ ﻗﺪ ﺗﺨﺮج ﺑﺴﮭﻮﻟﺔ ﻣﻦ ﺣﺎﻟﺔ اﻟﺘﺰاﻣﻦ، ﻣﻤﺎ ﯾﺆدي إﻟﻰ اﻧﺨﻔﺎض ﻓﻲ إﻧﺘﺎج اﻟﻄﺎﻗﺔ. أﻣﺎ اﻟﺤﻠﻮل اﻟﺤﺎﻟﯿﺔ ﻣﺜﻞ اﻟﻜﺘﻞ اﻟﻘﺎﺑﻠﺔ ﻟﻠﻀﺒﻂ أو اﻷﻧﻈﻤﺔ ﻣﺘﻌﺪدة درﺟﺎت اﻟﺤﺮﯾﺔ، ﻓﺈﻧﮭﺎ ﺗﺰﯾﺪ ﻣﻦ اﻟﺘﻌﻘﯿﺪ واﻟﻮزن، ﻣﻤﺎ ﯾﺤﺪ ﻣﻦ ﺗﻄﺒﯿﻘﮭﺎ اﻟﻌﻤﻠﻲ ﯾﻘﺪم ھﺬا اﻟﻌﻤﻞ آﻟﯿﺔ ﺟﺪﯾﺪة ﺗﻌﺘﻤﺪ ﻋﻠﻰ أﺳﻄﻮاﻧﺔ ذات ﻗﻄﺮ ﻣﺘﻐﯿﺮ — وھﻲ ﺗﻘﻨﯿﺔ ﻋﻤﻠﯿﺔ ﺗﻌﻤﻞ ﻋﻠﻰ ﺿﺒﻂ ھﻨﺪﺳﺔ اﻷﺳﻄﻮاﻧﺔ ﻓﻲ اﻟﺰﻣﻦ اﻟﺤﻘﯿﻘﻲ ﺑﮭﺪف ﺗﺤﺴﯿﻦ ﻛﻔﺎءة ﺣﺼﺎد اﻟﻄﺎﻗﺔ ﻣﻦ VIV. ﺗﻌﺘﻤﺪ اﻵﻟﯿﺔ ﻋﻠﻰ ﻧﻈﺎم ﺑﻜﺮة ﻗﺎﺑﻞ ﻟﻠﺘﻤﺪد ﯾﻘﻮم ﺑﺘﺸﻮﯾﮫ اﻷﺳﻄﻮاﻧﺔ اﻟﺪاﺋﺮﯾﺔ اﻟﻤﺮﻧﺔ ﺷﻌﺎﻋﯿًﺎ، ﻣﻤﺎ ﯾﺆدي إﻟﻰ ﺗﻐﯿﯿﺮ دﯾﻨﺎﻣﯿﻜﻲ ﻓﻲ ﻗﻄﺮھﺎ ﻟﻀﺒﻂ اﻟﻤﻌﺎﻣﻼت ﻏﯿﺮ اﻟﺒﻌﺪﯾﺔ اﻟﺮﺋﯿﺴﯿﺔ اﻟﺘﻲ ﺗﺘﺤﻜﻢ ﻓﻲ ﺳﻠﻮك VIV. ھﺬه اﻟﻘﺪرة ﻋﻠﻰ اﻟﺘﻜﯿﻒ ﻓﻲ اﻟﺰﻣﻦ اﻟﺤﻘﯿﻘﻲ ﺗﻌﺰز ﻣﻘﺎوﻣﺔ اﻟﺘﻐﯿﺮات اﻟﺒﯿﺌﯿﺔ، ﻣﻤﺎ ﯾﻮﺳﻊ ﻧﻄﺎق اﻻرﺗﺒﺎط ﺑﺸﻜﻞ ﻛﺒﯿﺮ. ﺗﺘﻀﻤﻦ اﻷﺳﻄﻮاﻧﺔ ﻣﺤﻮﻻً ﺑﯿﺰو ﻛﮭﺮﺑﺎﺋﯿﺎ، وﻗﺪ ﺗﻢ ﺗﺤﻠﯿﻞ ﺗﻔﺎﻋﻞ اﻟﻨﻈﺎم اﻟﺜﻼﺛﻲ (اﻟﺴﺎﺋﻞ – اﻟﮭﯿﻜﻞ اﻟﺒﯿﺰو ﻛﮭﺮﺑﺎء) ﻋﺪدﯾًﺎ ﻟﺘﺤﺪﯾﺪ ﺣﺮﻛﺔ اﻷﺳﻄﻮاﻧﺔ وﺟﮭﺪ اﻟﺨﺮج واﻟﻄﺎﻗﺔ اﻟﻨﺎﺗﺠﺔ. ﺗﻢ اﺳﺘﺨﺪام ﻣﻨﮭﺠﯿﺔ ﻣﻔﺼﻮﻟﺔ ﻣﻦ ﻧﻮع Lagrange-Euler، ﺣﯿﺚ ﺗﻢ رﺑﻂ ﻣﺤﻠﻞ ﻣﺎﺋﻊ ﯾﻌﺘﻤﺪ ﻋﻠﻰ طﺮﯾﻘﺔ اﻟﻔﺮوق اﻟﺤﺠﻤﯿﺔ (FVM) ﻣﻊ ﻣﺤﻠﻞ إﻧﺸﺎﺋﻲ ﺑﯿﺰو ﻛﮭﺮﺑﺎﺋﻲ ﻣﺒﺮﻣﺞ ﺧﺼﯿﺼًﺎ، وذﻟﻚ ﻣﻦ ﺧﻼل ﻣﻜﺘﺒﺔ preCICE اﻟﺘﻲ ﺗﺘﯿﺢ ﺗﺒﺎدل اﻟﺒﯿﺎﻧﺎت ﺑﯿﻦ اﻟﻤﺤﻠﻠﯿﻦ أﺛﻨﺎء اﻟﺘﺸﻐﯿﻞ. ﺗﻢ إﺟﺮاء اﻟﺘﺤﻠﯿﻞ ﻟﻤﺠﻤﻮﻋﺔ ﻣﻦ ﺣﺎﻻت اﻟﻘﻄﺮ اﻟﻤﺘﻐﯿﺮ، وأظﮭﺮت اﻟﻨﺘﺎﺋﺞ ﺗﺤﺴﻨًﺎ ﻓﻲ ﻋﺮض ﻧﻄﺎق اﻟﺘﺰاﻣﻦ ﺑﻨﺴﺒﺔ 70٪ وزﯾﺎدة ﻓﻲ اﻟﺴﻌﺔ اﻟﻘﺼﻮى ﺑﻨﺴﺒﺔ 117٪ ﻣﻘﺎرﻧﺔ ﺑﺤﺎﻟﺔ اﻟﻘﻄﺮ اﻟﺜﺎﺑﺖ. ﻛﻤﺎ ﺗﻢ ﺗﺤﻘﯿﻖ زﯾﺎدة ﺑﻨﺴﺒﺔ 113٪ ﻓﻲ اﻟﺠﮭﺪ اﻷﻗﺼﻰ، وﺗﻮﻟﯿﺪ طﺎﻗﺔ أﻛﺒﺮ ﺑﺄﻛﺜﺮ ﻣﻦ 8 ﻣﺮات. وأظﮭﺮ اﻟﺘﺤﻠﯿﻞ أﯾﻀًﺎ ﺗﺄﺛﯿﺮ ﻣﻘﺎوﻣﺔ اﻟﺤﻤﻞ ﻋﻠﻰ أداء اﻟﺤﺼﺎد، ﺣﯿﺚ أﺛﺒﺘﺖ ﺣﺎﻻت اﻟﻘﻄﺮ اﻟﻤﺘﻐﯿﺮ ﻗﺪرة ﻋﻠﻰ ﻣﻘﺎوﻣﺔ ﺗﺄﺛﯿﺮ اﻟﺘﺨﻤﯿﺪ اﻟﻨﺎﺗﺞ ﻋﻦ اﻟﺘﻮﺻﯿﻞ اﻟﻜﮭﺮﺑﺎﺋﻲ. (shunt damping) ﺗُﻌﺪ ﺗﻘﻨﯿﺔ اﻟﺘﺤﻜﻢ اﻟﻤﻘﺘﺮﺣﺔ ﻣﺘﻌﺪدة اﻻﺳﺘﺨﺪاﻣﺎت، ﺣﯿﺚ ﯾﻤﻜﻦ ﺗﻮظﯿﻔﮭﺎ ﺳﻮاء ﻓﻲ ﻛﺒﺢ اﻻھﺘﺰازات اﻟﻨﺎﺗﺠﺔ ﻋﻦ اﻟﺪواﻣﺎت أو ﻓﻲ ﺗﻄﺒﯿﻘﺎت ﺣﺼﺎد اﻟﻄﺎﻗﺔ.
Recommended Citation
Mostafa, Ahmed Raafat, "WIDE LOCK-IN ENERGY HARVESTING FROM VORTEXINDUCED VIBRATIONS OF A DEFORMABLE CYLINDER" (2025). Theses. 1300.
https://scholarworks.uaeu.ac.ae/all_theses/1300
