In the processing industry where liquids are mixed, shear stress is one of the most important factors affecting the quality of the final product. The shear coefficient (Ns) serves as a quantitative measure of the intensity of the shear stress . This article discusses the concept of the shear coefficient, its significance, calculation methods, and application in various industries.
What is the part number (Ns)?
The part number is a dimensionless parameter :
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It represents the relationship between shear force and inertial force in a mixed system.
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It is defined as follows: Ns = (γ̇ × D) / V
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γ̇: shear rate (1/s)
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D: Impeller diameter (m)
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V: Linear speed of the fan (m/s)
The importance of downsizing in the industrial sector
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Quality control of sensitive products ( cells , polymers, proteins)
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Improving energy consumption in hybrid systems
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Predicting the rheological behavior of complex fluids
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Precise design of process equipment
How to calculate the cutting time
1. Theoretical approach
NS = (D x H x D) / (60 x W)
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N: Speed (rpm)
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D: Impeller diameter (m)
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V: Linear velocity (m/s)
2. Experimental methods
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Using the rotation scale
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Application of Particle Image Velocimetry ( PIV) technology
3. Computer-aided modeling of hydrodynamics
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Flow field modeling
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Analysis of shear stress distribution
Industrial applications of abbreviated numbers
1. Biotechnology industry
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Cell culture : The ideal value is 0.5–1.5.
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Industrial fermentation : nitrogen control to prevent cell damage
2. Polymer industry
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Polymerization process : Ns is normally 2-5
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Connection establishment: The importance of an even Ns distribution
3. Food industry
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Production of sauces and emulsions : approx. 1-3 nanoseconds
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Milk processing : nitrogen control to maintain protein structure
Table with the ideal cutting time
| industry | Optimal range for Ns | Effects of high nitrogen levels |
|---|---|---|
| biotechnology | 0.5-1.5 | Destruction of cells |
| polymer | 2-5 | Break the chains |
| Eat | 1-3 | Changes in taste and texture |
| pharmaceutical products | 0.3-1.2 | Decrease in biological activity |
Factors that influence the number of units
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Fan properties (type, diameter, speed)
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Rheological properties of liquids (viscosity, non-Newtonian behavior)
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Geometry of the tank (presence of partition walls, aspect ratio)
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Operating conditions (temperature and pressure)
CNC cutting solutions
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Adjust the rotation speed
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Change license type
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Improving tank design
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Use of viscosity-increasing additives
Problems and advanced solutions
Frequently Asked Questions
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Destruction of sensitive products
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inefficient energy consumption
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Uneven distribution of shear stress
New solutions
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Use smart variable speed fans
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Using the Ns sensor
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Developing Ns forecast models using machine learning
Finally
The part number (NS) is a powerful tool for the design and optimization of industrial mixing systems . A clear understanding of this concept and its practical application can improve production efficiency, increase product quality, and reduce operating costs.
Frequently Asked Questions
1. What is the difference between the number of cuts and the cutting speed?
The shear rate (γ̇) is a dimensionless parameter (1/s) and the shear number (Ns) is a dimensionless quantity that represents the force ratio.
2. How can the number of failures in the current system be measured?
Use rotary flow meters or flow visualization methods such as PIV.
3. Do all fluids have the same part number?
No, this number depends largely on the rheological properties of the fluid.
4. What are the risks of setting coin prices too high?
The molecular structure is destroyed, product quality decreases and energy consumption increases.
Keywords: shear number, Newton, shear stress, synthetic mixture, fluid rheology, momentum, shear-sensitive process