Hyperbolic Measuring Nozzle for Plastic Melt Viscosity
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Solution Overview
Problem
Existing measuring nozzles for determining elongational viscosity of plastic melts require high sensitivity pressure sensors and cannot directly connect to the outlet section due to channel narrowing, leading to measurement inaccuracies and damage from required drilling.
Innovation Solution
A measuring nozzle with a hyperbolic transition section that widens to match the inlet section width and steadily reduces height, allowing a constant mean expansion rate and increased pressure drop for accurate viscosity calculation, enabling use of commercially available pressure sensors and direct connection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a hyperbolic transition section with constant width is used, then a constant average strain rate is achieved, but the pressure drop is too low requiring high sensitivity pressure sensors
Solution Approach 1:
The patent applies local quality by varying the cross-sectional geometry along the flow direction. The transition section has a hyperbolic width profile to maintain constant strain rate, while the height is reduced at the outlet section to increase pressure drop. This localized geometric modification allows different sections to serve different functions: the hyperbolic width section ensures measurement accuracy through constant strain rate, while the reduced height section increases pressure drop for compatibility with standard pressure sensors.
2Ease of operation
If the flow channel narrows at the outlet section, then connection to pressure sensors is enabled, but measuring capillaries must be drilled which damages the polymer melt and falsifies results
Solution Approach 1:
The patent applies preliminary action by pre-designing connection openings in the outlet section walls before the measurement process. These openings allow direct connection of pressure sensors without requiring drilling during operation. The connection openings are strategically positioned to avoid interfering with the flow channel geometry and measurement process, thereby eliminating the need for damaging drilling operations that would otherwise compromise the polymer melt and falsify measurement results.
3Ease of operation
If the outlet section width is reduced to connect pressure sensors, then sensor connection is possible, but the aspect ratio requirement for viscosity determination is compromised
Solution Approach 1:
The patent applies dimensionality change by resolving the geometric conflict in different spatial dimensions. The outlet section width is maintained to satisfy the aspect ratio requirement (width/height ≥ 10) for accurate viscosity determination, while the height is reduced to enable pressure sensor connection. This dimensional separation allows both requirements to be satisfied simultaneously: the wide dimension ensures proper aspect ratio, while the reduced height dimension facilitates sensor connection without compromising measurement accuracy.
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 measuring accuracy and sensitivity, allowing commercially available pressure sensors to meet higher requirements and eliminating the need for measurement capillaries, while maintaining relevant aspect ratios for viscosity determination.
Implementation Method 1
a transition section (3) between the inlet and outlet sections (1, 2), in which the duct walls (4) delimiting the width of the flow duct converge in the direction of flow (5) according to a hyperbolic function and then diverge hyperbolically again
Implementation Method 2
This geometry leads to an increase in the pressure drop, on the basis of which the extensional viscosity is calculated
Data Source
Figure 1~2
AI summary
The invention relates to a measuring nozzle for determining the extensional viscosity of plastic melts during the processing thereof, comprising a flow channel having a rectangular cross section, which, between an inlet section (1) and an outlet section (2) of respectively constant cross section, has a transition section (3), the width of which tapers hyperbolically in the flow direction. In order to create advantageous measuring conditions, the width of the transition section (3), according to the invention, widens hyperbolically, following the taper, to the width of the outlet section (2) that corresponds to the width of the inlet section (1), and the height of the transition section (4) decreases continuously from the height of the inlet section (1) to the smaller height of the outlet section (2).