Jet Pump Nozzle Apparatus Leakage Flow Suppression
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Solution Overview
Problem
Conventional jet pumps in boiling water reactors experience excessive vibration due to leakage flows through slip joints, which reduces efficiency and increases pressure loss, limiting the effectiveness of existing solutions like labyrinth seals and fluid sealing joints.
Innovation Solution
A nozzle apparatus with a nozzle base and multiple nozzles forming narrowing portions to reduce the fluid passage cross-sectional area, combined with a throat design where the passage area diminishes towards the downstream end, reduces leakage and enhances the efficiency by increasing the flow rate and reducing pressure loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a slip joint structure is used to allow thermal expansion differences, then thermal stress is reduced, but leakage flow increases causing vibration
Solution Approach 1:
The invention applies local quality by creating a flow passage reduction portion at a specific location (lower end portion) of the throat, rather than modifying the entire structure. This localized modification reduces the cross-sectional area to limit leakage flow while preserving the slip joint's thermal expansion accommodation capability elsewhere in the structure.
2Object-affected harmful factors
If the flow passage cross-sectional area is reduced in the throat, then leakage flow is suppressed, but pressure loss increases
Solution Approach 1:
The invention changes the geometric parameter (cross-sectional area) of the flow passage at a specific location (lower end portion of throat) to reduce leakage flow. By carefully controlling the reduction to be gradual and localized, the design minimizes the negative impact on overall pressure loss while achieving effective leakage suppression.
3Loss of energy
If multiple nozzles are used to increase contact area between driving and suction flows, then mixing is promoted and mixing loss is decreased, but device complexity increases
Solution Approach 1:
The invention segments the nozzle structure into multiple individual nozzles arranged in an array. This segmentation increases the total contact area between driving flow and suction flow, improving mixing efficiency and reducing mixing loss, while each individual nozzle remains a simple, manufacturable component.
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 solution effectively suppresses vibration and improves the efficiency of the jet pump by minimizing leakage and compensating for efficiency losses, allowing for increased core flow rates with reduced power consumption.
Implementation Method 1
The nozzle increases the speed of the driving flow
Implementation Method 2
The cooling water around the nozzle in the downcomer is sucked into the bell mouth as a suction flow due to the working of the ejected driving flow
Implementation Method 3
The cooling water passes the throat, and flows into the diffuser
Data Source
AI summary
A nozzle apparatus of a jet pump includes a nozzle base member, and a plurality of nozzles installed to the nozzle base member and forming a plurality of narrowing portions, in which a fluid passage cross-sectional area of a driving fluid passage formed in the nozzle is reduced.