Vortex Generators in Compressor Diffuser Pipes

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Solution Overview

Problem

Gas turbine engine diffuser pipes face efficiency issues due to spatial constraints, leading to shorter lengths and increased turbulence, resulting in pressure losses and flow separation at bends, which compromise compressor performance.

Innovation Solution

Incorporating vortex generators downstream of the throat and upstream of the curved portion in diffuser pipes to generate vortices, which enhance mixing and delay flow separation, reducing pressure losses and improving compressor efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If the diffuser pipe length is increased to improve flow diffusion, then diffusion performance is improved, but spatial constraints prevent this in practical gas turbine engines

Engineering Contradiction:

Improveflow diffusion performanceVSAvoiddiffuser pipe length

Core Design Contradiction:

ProductivityVSLength of stationary object

Solution Approach 1:

The patent changes the flow regime parameter by introducing vortex generators that create controlled turbulence. This allows the shorter diffuser pipe to achieve better diffusion performance by transitioning from laminar to turbulent flow, which enhances mixing and momentum transfer across the boundary layer without requiring increased pipe length.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The vortex generators create rotational motion and vortices in the fluid flow. These mechanical vibrations and rotational flows enhance the mixing action within the diffuser pipe, improving diffusion efficiency through turbulent motion rather than relying solely on the pipe length for diffusion.

Inventive Principle:

Principle #18Mechanical vibration

2Length of stationary object

If a tight bend is formed in the diffuser pipe to compensate for shorter length, then spatial constraints are satisfied, but turbulence and non-streamline behavior cause pressure losses

Engineering Contradiction:

Improvediffuser pipe lengthVSAvoidpressure losses

Core Design Contradiction:

Length of stationary objectVSLoss of energy

Solution Approach 1:

The vortex generators are positioned upstream of the bend to pre-energize the boundary layer and create controlled vortices before the flow enters the curved section. This preliminary action reduces the severity of flow separation and pressure losses that would otherwise occur at the tight bend, allowing the bend to be tighter without excessive energy loss.

Inventive Principle:

Principle #10Preliminary action

3Productivity

If vortex generators are added to reduce flow separation and pressure losses, then compressor efficiency is improved, but device complexity increases

Engineering Contradiction:

Improvecompressor efficiencyVSAvoiddiffuser pipe structure

Core Design Contradiction:

ProductivityVSDevice complexity

Solution Approach 1:

The vortex generators are strategically positioned at specific locations within the diffuser pipe where they provide maximum benefit - downstream of the throat and upstream of the bend. This localized placement ensures that the complexity is concentrated only where needed to address specific flow problems, rather than throughout the entire diffuser pipe.

Inventive Principle:

Principle #3Local quality

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

The use of vortex generators in diffuser pipes reduces flow separation and pressure losses, enhancing compressor performance and stability, leading to improved efficiency and reduced risk of structural damage.

Implementation Method 1

one or more vortex generators projecting into the internal flow passage, the vortex generators being disposed downstream of the throat and upstream of the bend

Methodology Applied

Scientific EffectVortex generation: Vortex Ring

Implementation Method 2

generating vortices in the fluid flow within the internal flow passage downstream of the throat and upstream of the curved portion

Methodology Applied

Scientific EffectTurbulence: Turbulence

Data Source

PatentUS10502231B2Diffuser pipe with vortex generators

Publication Date: 2019.12.10 PRATT & WHITNEY CANADA CORP

AI summary

A diffuser for a centrifugal compressor includes a diffuser pipe having an internal flow passage extending therethrough between an inlet and an outlet, a bend in the internal flow passage disposed between the inlet and the outlet, and a throat defined in the internal flow passage downstream of the inlet and upstream of the bend. One or more vortex generators project into the internal flow passage, and the vortex generators are disposed downstream of the throat and upstream of the bend. A method for diffusing fluid flow in a diffuser of a compressor is also described. In operation, the vortex generators engage fluid flow in the internal flow passage to generate downstream vortices.