Axial Turbomachine Stator Ailerons Reduce Suction Side Stalling

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

Existing stators in axial turbomachines face inefficiencies due to stalling and entropy issues, which reduce the turbomachine's performance and output pressure, despite advancements in stator designs like intermediate blades and slats on the suction side of blades.

Innovation Solution

The introduction of auxiliary stator blades that are strategically positioned and geometrically designed to extend parallel to main blades, overlap them axially, and create negative pressure areas to deflect flow towards the trailing edge, thereby reducing stalling and enhancing the flow straightening capability of the stator.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If intermediate blades are added to reduce stalling at the shell, then stalling at the shell is reduced, but stalling still occurs on the suction side of the blades creating vortices that reduce efficiency

Engineering Contradiction:

Improvestalling reduction at shellVSAvoidenergy loss from vortices on suction side

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The stator is divided into main blades and auxiliary blades with distinct functions. Main blades handle the primary flow while auxiliary blades specifically address suction side stalling. This segmentation allows each blade type to be optimized for its specific role, resolving the contradiction by treating different stalling problems separately rather than with a single blade design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Auxiliary blades are positioned specifically at the suction side region where stalling occurs, rather than uniformly distributing all blades. The auxiliary blades have different dimensions and positioning (recessed by 10-30mm) tailored to the local flow conditions on the suction side, addressing the specific problem area without affecting other regions unnecessarily.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If slats are located on the suction side of each blade to reduce secondary flows, then secondary flows are reduced, but stalling occurs on the suction surface close to the trailing edge generating entropy

Engineering Contradiction:

Improvesecondary flow reductionVSAvoidstalling on suction surface near trailing edge

Core Design Contradiction:

Loss of energyVSReliability

Solution Approach 1:

The blade system is segmented into main blades with slats for handling secondary flows, and separate auxiliary blades positioned downstream to handle trailing edge stalling. This segmentation allows slats to focus on secondary flow control while auxiliary blades address the trailing edge stalling problem that slats cannot resolve.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

Auxiliary blades are positioned downstream of main blades to act on the flow after it has passed through the main blade trailing edge. This preliminary action at the correct location in the flow path prevents stalling from developing in the first place, rather than attempting to correct it after it occurs.

Inventive Principle:

Principle #10Preliminary action

3Loss of energy

If a plurality of slats are used to reduce secondary flows, then secondary flows are reduced, but the flow area in the annular stream is reduced creating pressure drops

Engineering Contradiction:

Improvesecondary flow reductionVSAvoidpressure drop in annular stream

Core Design Contradiction:

Loss of energyVSStress or pressure

Solution Approach 1:

Instead of using multiple slats across the entire blade span, the system segments the function between main blades with limited slats and separate auxiliary blades positioned downstream. This reduces the total number of flow-blocking elements in the annular stream while still achieving secondary flow control and stalling prevention.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution moves from a two-dimensional array of slats across the blade span to a three-dimensional arrangement where auxiliary blades are positioned downstream at specific axial locations. This dimensional change allows flow control without uniformly blocking the annular stream cross-section, reducing pressure drops.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

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 improves the stator's ability to straighten flows, reduces stalling, increases the force exerted by blades, and allows for a potential reduction in the number of blades, leading to increased efficiency and cost-effectiveness of the turbomachine.

Implementation Method 1

each auxiliary blade being configured to create a negative pressure area indirectly contributing to straightening the flow

Methodology Applied

Scientific EffectNegative pressure area creation: Bernoulli Effect

Data Source

PatentUS9739154B2Axial turbomachine stator with ailerons at the blade roots

Publication Date: 2017.08.22 TECHSPACE AERO

AI summary

The present application relates to the compressor stator of an axial turbomachine. The stator comprises an annular row of main stator blades and auxiliary blades each of which are associated with a main blade. The auxiliary blades are located at the trailing edges of the main blades and are in the vicinity of the pressure faces of the main blades. The auxiliary blades are aligned to generate a low-pressure area at the trailing edges of the main blades. Thus, a flow bypassing a main blade by its suction face is sucked in by the low-pressure area when it approaches the trailing edge of the main blade. Stalling is thus avoided and the efficiency of the machine is improved.