Tandem Blade Row Profile Depth for Flow Separation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Turbomachinery, such as fans and compressors, face limitations in aerodynamic capacity and efficiency due to boundary layer growth and detachment near hub and casing walls, particularly under high aerodynamic loads, where conventional blade row group arrangements lead to separated boundary layer flows and increased pressure losses.
Innovation Solution
A blade row group design where the leading edge of one blade row is positioned near the trailing edge of the adjacent row, creating a secondary passage between the pressure and suction sides, with increased profile depths towards the main flow path boundary to enhance flow deflection and reduce separation, using normalized profile depths that increase by at least 10% at the boundary compared to the mean meridional flow line.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If conventional blade row group arrangements are used with high aerodynamic loads, then flow deflection is achieved, but boundary layer separation occurs in the edge zones on hub and housing walls
Solution Approach 1:
The patent applies local quality by differentiating the profile depths of blades in the front and rear blade rows. Specifically, blades in the front row have a first profile depth while blades in the rear row have a second profile depth that is smaller than the first. This local differentiation allows the front row to handle high aerodynamic loads while the rear row maintains favorable flow conditions, preventing boundary layer separation in edge zones.
Solution Approach 2:
The blade row group is segmented into two distinct blade rows with different profile depth characteristics. The front blade row is designed with larger profile depths to manage the primary flow deflection and aerodynamic loads, while the rear blade row has smaller profile depths to maintain attached flow. This segmentation allows each row to be optimized for its specific functional role, resolving the contradiction between achieving flow deflection and preventing separation.
2Productivity
If profile depth is increased to enhance flow deflection, then aerodynamic capacity improves, but boundary layer growth and detachment worsen
Solution Approach 1:
The invention applies local quality by creating a spatial variation in profile depth across different blade rows. The front blade row utilizes larger profile depths to maximize flow deflection and aerodynamic capacity, while the rear blade row employs smaller profile depths to maintain favorable pressure gradients and prevent boundary layer detachment. This localized optimization resolves the contradiction between enhancing productivity and reducing harmful effects.
3Ease of manufacture
If uniform profile depth is used across all blades, then manufacturing is simplified, but flow behavior deteriorates in edge areas
Solution Approach 1:
The patent implements local quality by specifying that blades in the front row have a first profile depth while blades in the rear row have a second profile depth. This deliberate non-uniformity in profile depth across different blade rows optimizes the flow behavior in edge areas, preventing boundary layer separation while maintaining acceptable manufacturing complexity through the systematic differentiation between rows.
4Power
If blade rows are positioned close together to form secondary passage, then flow deflection is enhanced, but pressure losses increase due to interference
Solution Approach 1:
The invention applies local quality by differentiating profile depths between front and rear blade rows, which optimizes the secondary passage geometry. The larger profile depth in the front row combined with the smaller profile depth in the rear row creates an optimized flow path that enhances flow deflection while minimizing adverse interference effects and pressure losses in the secondary passage region.
Data Source
Figure 1
Figure 2
Figure 3
AI summary
The invention relates to a blade row group that can be arranged in a main flow path of a turbomachine and consists of N adjacent member blade rows that are fixed relative to each other in both the meridional direction (m) and the circumferential direction (u), wherein the number N of member blade rows is greater than or equal to 2 and (i) denotes the running index with values between 1 and N. A front member blade row with front blades (i) having leading and trailing edges, and a rear member blade row with rear blades (i+1) having leading and trailing edges are provided.It is provided that at least one of the normalized airfoil depths, namely the normalized airfoil depth In(i) of the leading blade, the normalized airfoil depth In(i+1) of the trailing blade, the normalized additive airfoil depth laddn and/or the normalized effective airfoil depth leffn of a blade row pairing (i) and (i+1) in the area between the mean meridional streamline (SLM) and at least one of the main flow path boundaries (HB) in the direction of the main flow path boundary (HB), increases at least locally.