Rotary Machine Blade Internal Passage Flow Separation Control
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Solution Overview
Problem
Flow separation near the surface of blades in rotary machines leads to decreased performance and efficiency, as existing designs fail to effectively manage separation and associated losses.
Innovation Solution
The blade design incorporates an internal passage with a first opening end on the pressure or suction surface within 0.3L from the base end and a second opening end closer to the tip, utilizing centrifugal force to draw in flow from the separation-prone region, with radial-directional passage portions and strategically angled intake and outflow portions to enhance fluid pressurization and momentum transfer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an internal passage is introduced to reduce flow separation, then flow separation is reduced, but the device complexity increases
Solution Approach 1:
The internal passage is segmented into multiple functional portions: a radial-directional passage portion for centrifugal pressurization, an intake portion for flow entry, and an outflow portion for flow discharge. This segmentation allows each portion to be optimized for its specific function while collectively solving the flow separation problem without requiring complete structural redesign
Solution Approach 2:
The internal passage is positioned to open at specific locations on the blade surface (within 0.3L from the base end) where flow separation is most likely to occur. The passage geometry and orientation are locally optimized to match the flow patterns and pressure gradients at each specific location, providing targeted separation control
2Reliability
If the first opening end is positioned closer to the base end to capture separation flow, then separation suppression is improved, but the pumping pressure increase is reduced
Solution Approach 1:
The internal passage is oriented in the radial direction (blade height direction) rather than purely in the chordwise direction. This radial orientation allows the passage to simultaneously achieve two objectives: capturing separation flow at the blade surface and utilizing the radial pressure gradient to generate pumping pressure increase through centrifugal force
3Power
If the internal passage is designed with radial-directional passage portion, then centrifugal pumping effect is enhanced, but the manufacturing precision requirements increase
Solution Approach 1:
The passage geometry parameters (cross-sectional area, orientation angle, length) are optimized to achieve the desired centrifugal pumping effect. The radial-directional passage portion is designed with specific dimensional relationships that maximize the conversion of rotational kinetic energy to pressure energy, while the parameters are selected to be within manufacturable tolerances
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 configuration effectively reduces flow separation and tip leakage, improving the efficiency and performance of rotary machines by utilizing centrifugal pumping effects and strategic passage designs to manage fluid flow and momentum.
Implementation Method 1
a pressure increase is caused by a centrifugal force (pumping pressure increase) due to the radius difference between the first opening end at the radially inner side (at the side of the base end) and the second opening end at the radially outer side (at the side of the tip end)
Data Source
AI summary
A blade includes: an airfoil portion having a pressure surface and a suction surface each of which extends between a base end and a tip end along a blade height direction between a leading edge and a trailing edge; and an internal passage passing through an inside of the airfoil portion, the internal passage having a first opening end opening to one of the pressure surface or the suction surface and a second opening end which is positioned closer to the tip end than the first opening end in the blade height direction and opening to a surface of the airfoil portion. When L is a length from the base end to the tip end in the blade height direction, a distance from the base end to the first opening end in the blade height direction is not less than zero and not greater than 0.3 L.