Gas-Turbine Compressor Bleed-Air Tapping Geometry

Solution Overview

Problem

The existing bleed-air tapping geometries in gas-turbine compressors are not optimally adapted to the flow conditions, leading to flow separation, high pressure losses, and inefficient compressor operation, which can result in stability issues and mechanical excitation of compressor blades.

Innovation Solution

An optimized bleed-air tapping geometry is designed by inclining it circumferentially at a defined angle and providing an axial profile adapted to the flow direction, using specific geometrical and machine-specific parameters such as the metal exit angle, circumferential speed, and air quantity, to minimize pressure losses and reduce swirl, ensuring smooth flow entry and maximum static pressure recovery.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Device complexity

If a simple bleed-air tapping geometry (circumferential slot or discrete hole) is used, then the device complexity is low and manufacturing is easy, but pressure losses are high and flow separation occurs

Engineering Contradiction:

Improvebleed-air tapping geometry complexityVSAvoidpressure loss in bleed-air tapping

Core Design Contradiction:

Device complexityVSLoss of energy

Solution Approach 1:

The patent applies local quality by adapting the bleed-air tapping geometry specifically to the local flow conditions at the tapping point. The geometry is optimized based on the local flow direction (determined by upstream blade outflow angles) and local velocity, creating a tailored entrance shape that matches the incoming flow characteristics rather than using a universal simple geometry.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes geometric parameters of the bleed-air tapping based on machine-specific parameters. The entrance angle of the bleed-air tapping is calculated from the flow direction βE using the formula α = βE + 10°, and the area is determined from the required bleed air quantity ξ. These parameter adjustments optimize flow entry and reduce pressure losses.

Inventive Principle:

Principle #35Parameter changes

2Ease of manufacture

If a simple bleed-air tapping geometry is used, then manufacturing is easy, but compressor efficiency and stability are reduced

Engineering Contradiction:

Improvebleed-air tapping manufacturing easeVSAvoidcompressor stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent applies local quality by adapting the bleed-air tapping geometry specifically to the local flow conditions at the tapping point. The geometry is optimized based on the local flow direction (determined by upstream blade outflow angles) and local velocity, creating a tailored entrance shape that matches the incoming flow characteristics rather than using a universal simple geometry.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent converts the potentially harmful swirling flow into a beneficial aligned flow by designing the bleed-air tapping entrance angle to match the local flow direction. This alignment prevents flow separation and adverse interactions that would otherwise harm compressor stability, while still maintaining manufacturing feasibility.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

3Ease of manufacture

If bleed air is tapped with simple geometry, then production costs are low, but flow separation and mechanical excitation of blades occur

Engineering Contradiction:

Improveproduction costVSAvoidflow separation and blade excitation

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent applies local quality by adapting the bleed-air tapping geometry specifically to the local flow conditions at the tapping point. The geometry is optimized based on the local flow direction (determined by upstream blade outflow angles) and local velocity, creating a tailored entrance shape that matches the incoming flow characteristics rather than using a universal simple geometry.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The patent changes geometric parameters of the bleed-air tapping based on machine-specific parameters. The entrance angle is calculated as α = βE + 10° where βE is the local flow direction, and the area is determined from the required bleed air quantity. These parameter adjustments prevent flow separation and blade excitation while maintaining cost-effectiveness.

Inventive Principle:

Principle #35Parameter changes

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 minimizes pressure losses and improves compressor efficiency and stability, enabling more efficient bleed air tapping for applications like turbine cooling and cabin pressurization, while maintaining production simplicity and avoiding increased costs or weight.

Implementation Method 1

The bleed-air tapping geometry is provided with an adapted entrance angle such that the flow direction is aligned with the bleed-air tapping geometry

Methodology Applied

Scientific EffectFlow direction adaptation:

Implementation Method 2

The flow can enter the bleed-air tapping geometry without disturbance, thereby minimizing the local total pressure loss

Methodology Applied

Scientific EffectPressure loss minimization:

Implementation Method 3

is deflected such within the bleed-air tapping geometry that the swirl in the flow is reduced to zero, thereby obtaining a maximum of static pressure recovery

Methodology Applied

Scientific EffectSwirl reduction:

Data Source

PatentUS8220276B2Gas-turbine compressor with bleed-air tapping

Publication Date: 2012.07.17 ROLLS ROYCE DEUT LTD & CO KG

AI summary

A gas-turbine compressor has a casing (1) in which a rotor hub (2) is rotatably borne, and a compressor duct (9) being disposed between the casing (1) and the rotor hub (2), in which at least one rotor (4), which is rotatable about a machine axis (5), and one stator (5) are arranged. Recesses (12) of a bleed-air tapping device (6) are provided in the casing (1), which—in at least one circumferential area (11)—are arranged circumferentially to each other recess (12) and include a circumferential leading edge (16) in the circumferential direction and a circumferential trailing edge (17), each of which includes an identical angle βE with the surface (18) of the casing (1).