Flextensional Piezoelectric Harvester for Harsh Flow Environments
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional bimorph cantilever-type piezoelectric energy harvesters have low transverse bending stiffness, leading to high stresses and short lifetimes due to brittleness, making them unsuitable for generating power in harsh environments like oil wellbores where large deformations occur.
Innovation Solution
A flow energy harvesting system featuring a flextensional member with a frame and cantilever, where a stack of piezoelectric elements is housed in the frame, and the frame is designed to deform and generate current through the piezoelectric effect due to fluid flow-induced aeroelastic flutter, with a resonant frequency lower than the cantilever's, allowing for increased thickness and reduced fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional bimorph cantilever-type piezoelectric energy harvesters are used, then power can be generated with small amplitude forces, but the device has short lifetime due to brittleness and large stresses
Solution Approach 1:
The device is segmented into two distinct functional components: a flextensional member (frame and cantilever) that interacts with the fluid flow and undergoes large deformations, and a stack of piezoelectric elements housed in an interior cavity that generates electricity. This segmentation allows the structural component to handle mechanical stresses while the piezoelectric elements remain protected from direct fluid exposure and excessive deformation.
Solution Approach 2:
The frame acts as an intermediary between the fluid flow and the piezoelectric elements. The frame deforms in response to fluid forces and transmits this deformation to the piezoelectric elements, which convert the mechanical deformation into electrical energy. This intermediary structure protects the piezoelectric elements from direct exposure to harsh fluid conditions while still enabling energy harvesting.
2Power
If piezoelectric elements are exposed to fluid flow for energy harvesting, then power can be generated, but corrosion and erosion reduce device lifespan
Solution Approach 1:
The frame serves as a protective intermediary that separates the piezoelectric elements from direct contact with the corrosive fluid flow. The frame undergoes the mechanical interaction with the fluid while shielding the piezoelectric elements housed in the interior cavity from corrosion and erosion, thereby extending device lifespan.
Solution Approach 2:
The frame and cantilever structure acts as a flexible shell that encapsulates and protects the piezoelectric elements. This shell allows the device to interact with fluid flow for energy harvesting while protecting the internal piezoelectric components from harmful environmental factors such as corrosion and erosion.
3Productivity
If the resonant frequency of the frame and piezoelectric elements is lower than the cantilever, then energy conversion efficiency is enhanced, but the structural design becomes more complex
Solution Approach 1:
The device utilizes dynamic resonance principles where the frame and piezoelectric elements are designed with a specific resonant frequency lower than that of the cantilever. This dynamic design allows the system to efficiently convert fluid flow energy into electrical energy at the optimized resonant frequency, enhancing overall energy conversion efficiency.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This design enhances energy conversion efficiency and extends the lifespan of the device by isolating piezoelectric elements from fluid flow, reducing corrosion and erosion, and enabling power generation locally near electronic devices without the need for long-distance power transmission.
Implementation Method 1
The frame is configured to deform and elongate the stack of piezoelectric elements to generate a current based on the piezoelectric effect when a fluid flows through the spline-shaped flow channel
Implementation Method 2
when a fluid flows through the spline-shaped flow channel and generates unbalanced forces on the cantilever due to aeroelastic flutter
Data Source
AI summary
A flow energy harvesting system including a nozzle-diffuser defining a spline-shaped flow channel and a flow energy harvesting device in the spline-shaped flow channel of the nozzle-diffuser. The spline-shaped flow channel includes a converging portion, a diverging portion, and a constriction section between the converging and diverging portions. The flow energy harvesting device includes a flextensional member having a frame and a cantilever extending outward from the frame, and a stack of piezoelectric elements housed in an interior cavity defined in the frame. The cantilever is a non-piezoelectric material. The frame of the flextensional member is in the converging portion and the cantilever is in the constriction section of the spline-shaped flow channel. The frame is configured to deform and elongate the piezoelectric elements to generate a current based on the piezoelectric effect when a fluid flows through the spline-shaped flow channel and generates unbalanced forces on the cantilever due.