Multi-stage Hydraulic Machine Blade Count Optimization
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Solution Overview
Problem
Existing hydraulic machines face challenges in maximizing performance, optimizing cavitation behavior, and minimizing pressure pulsations, particularly in high-power applications like those with over 10 MW capacity, where the first stage affects cavitation and the top stage influences pressure pulsations.
Innovation Solution
A multi-stage hydraulic machine design with a smaller number of rotor blades in the first stage compared to subsequent stages, and potentially fewer blades in the top stage, along with varying blade lengths and increased distances between stationary and rotor blades in critical stages to enhance cavitation and pressure pulsation management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the number of rotor blades is increased to maximize performance, then the power output increases, but cavitation behavior deteriorates
Solution Approach 1:
The patent applies different numbers of rotor blades to different stages of the hydraulic machine. Specifically, the first stage has a different number of rotor blades compared to the second and subsequent stages. This local differentiation allows optimization of cavitation behavior in the first stage while maintaining performance in other stages, resolving the contradiction between overall power output and cavitation performance.
2Use of energy by moving object
If the number of rotor blades is increased to maximize performance, then the energy transfer improves, but pressure pulsations increase
Solution Approach 1:
The patent differentiates the number of rotor blades in the uppermost stage from other stages. The uppermost stage has a specific number of rotor blades optimized to minimize pressure pulsations, while other stages have different numbers optimized for energy transfer. This local optimization resolves the contradiction between energy transfer efficiency and pressure pulsation minimization.
3Ease of manufacture
If all impellers have the same number of blades for simplicity, then manufacturing is easier, but cavitation and pressure pulsation behavior cannot be optimized
Solution Approach 1:
The patent specifies different numbers of rotor blades for different stages (first stage versus second and subsequent stages), creating local differentiation in the blade configuration. This approach prioritizes hydraulic performance optimization (cavitation and pressure pulsation behavior) over manufacturing uniformity, while still maintaining reasonable manufacturing complexity through a limited number of different blade counts.
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 improves cavitation behavior and reduces pressure pulsations, maximizing performance while maintaining defined cavitation safety and minimizing pressure pulsations in high-power hydraulic machines, particularly during modernization projects where design flexibility is limited.
Implementation Method 1
an impeller (2) connected to the shaft (1), in each case designed for at least partially radial flow
Data Source
Figure 1
Figure 2
AI summary
The invention relates to a hydraulic machine having at least two stages, said hydraulic machine comprising a shaft (1) and impeller wheels (2), wherein: each stage comprises an impeller wheel (2); each impeller wheel (2) comprises a plurality of blades (4), is connected to the shaft (1), and is of the radial type; the hydraulic machine comprises a low-pressure side and a high-pressure side; a first stage is arranged adjacent to the low-pressure side of the hydraulic machine; and the number of blades (4) of the impeller wheel (2) of the first stage is smaller than the number of blades (4) of any impeller wheel (2) of the remaining stages.