Thermowell Dimples Mitigate Vortex Shedding
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Solution Overview
Problem
Existing flow line inserts, such as thermowells, experience vibration-induced stresses and resonance due to vortex shedding, leading to mechanical failures and inaccurate parameter measurement, which conventional designs like shorter lengths or thicker walls often fail to adequately address.
Innovation Solution
Incorporating dimples on the outer surface of the inserts, which reduce vortex-induced vibrations by distributing drag forces and minimizing resonance effects, with dimples having specific depth and diameter ratios and distribution patterns tailored to the process fluid parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional thermowell designs are used, then the structure is simple and easy to manufacture, but vibration-induced stresses and resonance occur due to vortex shedding, leading to mechanical failures
Solution Approach 1:
The patent applies local quality by adding dimples only to specific regions of the thermowell outer surface where vortex shedding occurs, rather than modifying the entire structure. The dimples are strategically positioned to disrupt vortex formation while maintaining the overall simplicity of the thermowell design, thus improving reliability without excessive complexity
Solution Approach 2:
The patent uses curved dimples with specific geometric parameters (depth, diameter, spacing) on the thermowell surface. These curved features alter the flow pattern around the thermowell, reducing vortex-induced vibrations and resonance effects, thereby improving mechanical failure resistance
2Measurement precision
If the thermowell length is increased to improve measurement accuracy, then temperature measurement precision improves, but vibration-induced stresses increase due to greater exposure to vortex shedding
Solution Approach 1:
The dimples are applied locally to the thermowell surface in regions where vortex shedding occurs, allowing the thermowell to maintain its full length for accurate temperature measurement while only modifying specific areas to reduce vibration-induced stresses
Solution Approach 2:
The patent converts the harmful vortex shedding forces into beneficial reduced vibrations by using dimples to disrupt the vortex formation process. The dimples alter the flow pattern in a way that reduces the intensity of vortex-induced vibrations, allowing longer thermowells to maintain both measurement accuracy and vibration resistance
3Strength
If the thermowell wall thickness is increased to reduce vibration-induced stresses, then mechanical strength improves, but the interior cavity volume decreases, affecting sensor placement and measurement accuracy
Solution Approach 1:
The dimples on the thermowell surface alter the flow pattern and reduce vortex-induced vibrations, allowing the use of thinner walls compared to conventional designs. This maintains interior cavity volume for proper sensor placement while still providing adequate vibration stress resistance
Solution Approach 2:
The patent converts the potential weakness of thinner walls into an advantage by using dimples to reduce the intensity of vortex-induced vibrations. This allows the thermowell to maintain structural integrity with thinner walls, preserving interior cavity volume for sensor accommodation
4Reliability
If dimples are added to the outer surface to reduce vortex-induced vibrations, then vibration and stress are reduced, but manufacturing complexity increases
Solution Approach 1:
The dimples are added only to specific regions of the thermowell surface rather than the entire surface, reducing the overall manufacturing complexity. The localized application of dimples maintains vibration reduction benefits while minimizing the additional manufacturing steps required
Solution Approach 2:
The patent specifies particular geometric parameters for the dimples (depth, diameter, spacing patterns) that can be optimized for different thermowell sizes and applications. These standardized parameter ranges facilitate manufacturing by providing clear design guidelines while achieving effective vibration reduction
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
The dimpled design significantly reduces vibration and stress on the inserts, enhancing their durability and accuracy in measuring process fluid parameters by mitigating vortex-induced oscillations and resonance frequencies.
Implementation Method 1
reduce vibration in response to vortex shedding
Implementation Method 2
distributing drag forces and minimizing resonance effects
Data Source
AI summary
An example implementation of the subject matter described within this disclosure is a thermowell with the following features. A body has a closed end, an open end, an outer surface, and defining an interior cavity starting prior to the closed end and terminating at the open end. The outer surface defines dimples that reduce vibration in response to vortex shedding.