Turbopump Impeller Clearance Control for Axial Thrust Balance
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Solution Overview
Problem
Existing turbopumps face challenges in actively controlling axial thrust due to variations in operation environments, leading to potential damage from uncontrolled axial loads on bearings and rocket engines.
Innovation Solution
A turbopump design that automatically adjusts axial thrust by varying the clearance between the impeller and casing based on fluid pressure differences, using protrusions and projections to control the movement of the impeller and rotational shaft, thereby maintaining balance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If seals are installed on shoulders to adjust shroud area and reduce net load, then axial thrust control is improved, but the system loses adaptability when operation environment changes
Solution Approach 1:
The patent implements a dynamic axial thrust control mechanism where the impeller can axially move relative to the casing. This movement changes the clearance between the impeller shroud and casing, which dynamically adjusts the high-pressure fluid area behind the impeller. As operating conditions change, the axial position of the impeller automatically adjusts to maintain optimal thrust balance, resolving the contradiction between fixed seal configurations and adaptive thrust control.
Solution Approach 2:
The patent changes the geometric parameter of the clearance between the impeller and casing to control axial thrust. By varying this clearance through impeller axial movement, the effective area of the high-pressure region behind the impeller changes, which directly adjusts the balancing force. This parameter change mechanism enables adaptive response to varying operational conditions while maintaining reliable thrust control.
2Ease of manufacture
If fixed seals are used to control axial thrust, then manufacturing is simplified, but the system cannot actively respond to axial thrust variations
Solution Approach 1:
The patent employs a self-regulating mechanism where the impeller's axial position is automatically adjusted by the balance between axial thrust forces. The high-pressure fluid behind the impeller creates a balancing force that counteracts the axial load, and this balance automatically positions the impeller at the optimal clearance without requiring external control systems or complex active mechanisms. This self-service approach maintains ease of manufacture while achieving active response capability.
3Reliability
If additional axial-trust control structures are added, then thrust balancing is improved, but device complexity increases
Solution Approach 1:
The patent makes the impeller serve multiple functions: it not only pressurizes the fluid through centrifugal force but also acts as the axial thrust control element through its ability to move axially. The casing similarly serves dual purposes as both the containment structure and the reference surface for the variable clearance. This multi-functionality achieves reliable thrust balancing without adding separate control structures, maintaining device simplicity.
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 design effectively balances axial thrust, preventing damage to bearings and ensuring the durability and reliability of the turbopump by dynamically responding to changes in operational conditions.
Implementation Method 1
an impeller for pressurizing the fluid by centrifugal force
Implementation Method 2
axial thrust is controlled as a clearance formed between the impeller and the casing in a length direction of the rotational shaft varies according to a fluid pressure difference between front and rear sides of the impeller
Data Source
AI summary
A turbopump includes a casing, a rotational shaft rotatably supported on the casing, and an impeller mounted on a side of the rotational shaft and pressurizing a fluid flowing into the impeller from an inlet of the casing, wherein axial thrust is controlled as a clearance formed between the impeller and the casing in a length direction of the rotational shaft varies according to a fluid pressure difference between front and rear sides of the impeller.