Measuring Nozzle With Hyperbolic Transitional Section For Polymer Viscosity
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Solution Overview
Problem
Existing measuring nozzles for determining extensional viscosity of polymer melts face challenges in achieving high measuring accuracy due to the limitations of commercially available pressure sensors, which require high responsiveness and are prone to deposits in measuring capillaries.
Innovation Solution
The measuring nozzle design includes a transitional section subdivided into an inlet-side zone with continuously converging channel walls and an outlet-side zone with parallel channel walls that converge hyperbolically, maintaining a constant mean strain rate and increasing pressure loss, allowing for direct connection of commercially available pressure sensors without measurement capillaries.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional transitional section with hyperbolic tapering is used, then a constant mean strain rate is achieved, but the pressure drop is too low for accurate measurement with commercial sensors
Solution Approach 1:
The transitional section is divided into two distinct zones: an inlet-side zone with continuously converging channel walls and an outlet-side zone with parallel channel walls. This segmentation allows each zone to perform a specific function - the inlet zone maintains constant mean strain rate while the outlet zone increases pressure drop, resolving the contradiction between measurement accuracy and sufficient pressure signal
Solution Approach 2:
Different geometric characteristics are applied to different parts of the transitional section. The inlet-side zone has continuously converging walls for constant strain rate, while the outlet-side zone has parallel walls for increased pressure loss. This local differentiation optimizes each section for its specific purpose, achieving both accurate measurement conditions and sufficient pressure drop
2Measurement precision
If high responsiveness pressure sensors are used to achieve accurate measurements, then measurement accuracy improves, but the system complexity and cost increase
Solution Approach 1:
The geometric parameters of the flow channel are modified to change the pressure drop characteristics. By designing the outlet-side zone with parallel walls and specific dimensions, the pressure loss is increased to a level that can be accurately measured by commercial sensors with moderate responsiveness, eliminating the need for specialized high-performance sensors
3Ease of operation
If measurement capillaries are drilled into the measuring nozzle for sensor connection, then sensor integration is enabled, but deposits in the capillaries cause measurement errors
Solution Approach 1:
The measurement connection is extracted from the internal flow path by providing connection bores that lead to the outer surface of the measuring nozzle. This allows pressure sensors to be connected without requiring capillaries drilled into the flow channel, eliminating the deposit problem while maintaining ease of connection
Solution Approach 2:
Connection bores serve as intermediaries between the internal flow channel and external pressure sensors. These bores provide a dedicated pathway for pressure measurement that is separate from the main polymer melt flow, preventing deposits from blocking the measurement path while enabling sensor integration
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, enabling the use of commercially available pressure sensors to achieve precise extensional viscosity measurements by increasing the pressure drop and maintaining a constant mean strain rate throughout the flow channel.
Implementation Method 1
the transitional section comprises an inlet-side zone in which the mutual distance of the two channel walls between the two hyperbolic channel walls decreases continuously in the direction of flow
Implementation Method 2
two of the channel walls disposed opposite one another in pairs extend parallel to one another, while the two channel walls arranged therebetween converge hyperbolically in the flow direction
Data Source
AI summary
The invention relates to a measuring nozzle for determining the extensional viscosity of polymer melts during their processing, comprising a flow channel which has a rectangular cross-section and which has a transitional section (3) between an inlet section (1) and an outlet section (2) with respective constant cross-section, which transitional section tapers hyperbolically in the flow direction (8) between two mutually opposite channel walls (6 and 7). In order to provide advantageous measuring conditions it is proposed that the transitional section (3) comprises an inlet-side zone (4) in which the mutual distance of the two channel walls (7) between the two hyperbolic channel walls (6) decreases continuously in the direction of flow (8), and an outlet-side zone (5) which adjoins the inlet-side zone and in which two of the channel walls (6, 7) disposed opposite one another in pairs extend parallel to one another, while the two channel walls (7) arranged therebetween converge hyperbolically in the flow direction (8).