Turbomachine Blade Grid Platform Recesses for Secondary Flow Control
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Solution Overview
Problem
Turbomachines experience significant secondary flows and associated pressure losses due to the interaction of fluid flow with the side walls of the annular space, which current contouring techniques do not adequately address.
Innovation Solution
A blade grid segment with a platform surface featuring a recess that extends up to the first airfoil, where the depression touches the pressure side or trailing edge, reducing secondary flows by optimizing the geometry of the platform surface to minimize vortex formation and enhance flow alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional smooth platform surfaces are used, then manufacturing is simple, but secondary flows and pressure losses increase
Solution Approach 1:
The platform surface is given different local geometries through depressions and elevations at specific locations rather than being uniformly smooth. The depression is positioned downstream of the leading edges and the elevation upstream, creating localized flow control features that reduce secondary flows without complicating the entire structure.
Solution Approach 2:
The platform surface incorporates curved features in the form of a depression and an elevation rather than sharp angular transitions. These curved geometries help to guide the fluid flow smoothly and reduce vortex formation, thereby decreasing pressure losses while maintaining manufacturing feasibility.
2Loss of energy
If no platform surface contours are used, then the structure is simple, but secondary flows are strong
Solution Approach 1:
Instead of applying contours throughout the entire platform surface, the invention uses localized depression and elevation features at specific positions relative to the blade leading and trailing edges. This targeted approach reduces secondary flows where they are most problematic while keeping the overall structure relatively simple.
3Loss of energy
If the depression touches the first blade, then flow alignment is improved, but manufacturing precision requirements increase
Solution Approach 1:
The depression and elevation features are designed with predetermined dimensions and positions relative to the blade geometry. By establishing these features in advance during manufacturing, the flow alignment benefits are achieved without requiring complex real-time adjustments or extremely tight tolerances during assembly.
Data Source
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AI summary
A blade grid segment (110, 120, 130, 140, 150) of a blade grid for a turbomachine is disclosed, comprising a platform (10) with a platform surface and at least two blades (20, 30). The platform surface has a recess (111, 121, 131, 141, 151) extending towards the first blade, which contacts the pressure side (21) of the first blade downstream of 80% of the axial grid width (g) downstream of the leading edges (23, 33) and up to a maximum of 80% of the axial grid width (g) downstream of the leading edges (23, 33). At least one lowest point (112, 122) of the depression lies at least 90% of the axial grid width (g) downstream of the leading edges (23, 33). Also revealed are a blade grid, a blade channel, a platform, a turbomachine, and an aircraft engine.