Integrally Bladed Rotor Air Injection to Delay Flow Separation
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Solution Overview
Problem
The separation of working fluid from laminar flow to turbulent flow over the rotor blades in integrally bladed rotors reduces the aerodynamic efficiency of rotary machines, such as air cycle machines.
Innovation Solution
The integration of a rotor blade with an internal channel and strategically placed air outlets at the leading edge, which directs discharged air to delay the separation of the main flow, maintaining laminar flow and enhancing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If integrally bladed rotors are used to increase aerodynamic efficiency, then the rotor structure is simplified and manufacturing is easier, but the working fluid separates from laminar flow to turbulent flow over the rotor blades, reducing overall efficiency
Solution Approach 1:
The rotor blade is segmented into multiple functional zones with different surface properties. The leading edge portion has a first surface configuration optimized for flow attachment, while the trailing edge portion has a second surface configuration that promotes laminar flow maintenance. This segmentation allows each zone to perform its specific function optimally, preventing premature flow separation while maintaining the integral blade structure.
Solution Approach 2:
Different portions of the rotor blade are given different local surface qualities and geometries. The leading edge features a specific curvature and surface finish to delay flow separation, while the suction and pressure surfaces have differentiated profiles to maintain laminar flow characteristics. This local optimization resolves the contradiction by making the blade structure itself adaptive to flow conditions.
2Loss of energy
If the rotor blade geometry is modified to maintain laminar flow, then aerodynamic efficiency increases, but the device complexity increases due to internal channels and multiple air outlets
Solution Approach 1:
The internal cooling channels and flow control outlets are merged into the rotor blade structure itself, creating an integrated component rather than separate elements. The first and second air outlets are formed as integral parts of the blade body, eliminating the need for external ducts or separate flow control mechanisms. This merging reduces overall device complexity while achieving the laminar flow maintenance objective.
Solution Approach 2:
The rotor blade structure serves multiple functions simultaneously: it generates aerodynamic force, manages internal cooling flows, and controls external flow separation. The integrated air outlets serve both cooling and flow control purposes, while the differentiated surface configurations perform both flow attachment and laminar flow maintenance functions. This multi-functionality reduces the need for separate components, thereby reducing device complexity.
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 maintains laminar flow over the rotor blades, thereby increasing the aerodynamic efficiency of the air cycle machine by entraining the main flow with discharged air, reducing turbulence and improving overall performance.
Implementation Method 1
maintaining laminar flow and enhancing efficiency
Implementation Method 2
the separation of working fluid from laminar flow to turbulent flow over the rotor blades
Implementation Method 3
reduces the efficiency of the overall rotary machine
Implementation Method 4
entraining the main flow with discharged air
Data Source
Figure 1
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Figure 3
AI summary
An integrally bladed rotor (36) includes a rotor disk (114), rotor blade (112), internal channel (130) and air outlets (132). The rotor blade includes a body defined by a pressure surface (124) and suction surface (126) between a leading edge (116) and a trailing edge (118). The internal channel extends radially from the rotor disk internally within the body of the rotor blade. The air outlets are formed proximate the leading edge and extend within the body of the rotor blade to the internal channel.