Centripetal Air Bleed Fins for Turbomachine Compressor Rotor

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Solution Overview

Problem

Turbomachines experience significant turbulence and head losses in the annular chamber between compressor rotor disks due to centripetal air bleed, leading to increased specific consumption and elevated bleed air temperature, with existing radial fins failing to effectively reduce these issues.

Innovation Solution

The introduction of axially spaced, radially aligned deflector fins connected to the disks, which deflect the bleed air stream and limit eddies and turbulence, allowing the air to flow centripetally and reducing head losses by ensuring the air rotates at the same speed as the compressor rotor, thus enabling bleeding from a further upstream stage.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Temperature

If centripetal air bleed means with through passages in the wall are used, then cooling of downstream stages and turbine rims is achieved, but turbulence and head losses in the annular chamber increase

Engineering Contradiction:

Improvecooling of downstream stages and turbine rimsVSAvoidhead losses in the annular chamber

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The invention divides the air flow path into multiple controlled streams by introducing deflector fins that split the single through-passage flow into multiple smaller streams. This segmentation reduces turbulence intensity in each stream and allows more orderly centripetal flow along the disk surfaces, reducing overall head losses while maintaining effective cooling distribution.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The deflector fins act as intermediary elements between the through passages and the disk surfaces. These fins guide and condition the bleed air flow, transforming it from a turbulent jet into controlled boundary layer flows that follow the disk surfaces, thereby reducing energy losses while achieving the cooling function.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Temperature

If bleed air flow rate is increased to ensure proper cooling when Ke > 1, then cooling effectiveness improves, but specific consumption of the turbomachine increases

Engineering Contradiction:

Improvecooling effectiveness of turbine componentsVSAvoidspecific consumption of the turbomachine

Core Design Contradiction:

TemperatureVSLoss of energy

Solution Approach 1:

The invention changes the flow parameters (velocity distribution, flow direction, turbulence intensity) of the bleed air through the deflector fins. By transforming the flow into controlled boundary layer flows with lower turbulence and more uniform velocity distribution, the cooling effectiveness is maintained or improved at lower mass flow rates, reducing specific consumption.

Inventive Principle:

Principle #35Parameter changes

3Speed

If radial fins are arranged on the facing faces of the disks, then air speed in the interdisk chamber is reduced, but head losses in the central zone are not sufficiently reduced

Engineering Contradiction:

Improveair speed in the interdisk chamberVSAvoidhead losses in the central zone of the chamber

Core Design Contradiction:

SpeedVSLoss of energy

Solution Approach 1:

Instead of arranging fins in the radial plane (conventional approach), the invention positions deflector fins axially offset from the disks, creating a three-dimensional flow control structure. This axial offset allows the fins to interact with the flow in a different dimension, effectively guiding the centripetal flow and reducing head losses in the central zone where conventional radial fins fail.

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 solution reduces head losses and allows for bleeding air from a more upstream compressor stage, lowering the specific consumption and temperature of the turbomachine while maintaining the air's speed in alignment with the rotor, thereby enhancing efficiency and reducing energy expenditure.

Implementation Method 1

a portion of the air flowing in the flow section of the compressor is bled off via the through passages in the wall connecting the disks together, and it passes into the annular chamber where it flows centripetally along the disks of the rotor

Methodology Applied

Scientific EffectCentripetal flow:

Implementation Method 2

the fins extend in the central zone of the chamber, thereby serving to limit eddies and turbulence in this zone by forcing the air to flow centripetally

Methodology Applied

Scientific EffectTurbulence reduction: Turbulence

Implementation Method 3

The air that reaches the radial faces of the disks flows naturally along the disks towards the axis of rotation by forming layers on said disk of a kind that also occur as atmospheric or oceanic phenomena and that are known as Ekman layers

Methodology Applied

Scientific EffectEkman layers: Ekman layer

Data Source

PatentUS8894360B2Turbomachine compressor rotor including centripetal air bleed means

Publication Date: 2014.11.25 SAFRAN AIRCRAFT ENGINES SAS

AI summary

A turbomachine compressor rotor including at least two blade-carrying disks mounted on a common axis and connected together by a wall forming a substantially cylindrical surface of revolution, and a centripetal air bleed mechanism including air passages passing through the wall and radial fins for deflecting a stream of air leaving the passages in the wall, the fins being carried by one of the disks and being substantially in radial alignment with the passages through the wall.