Blade Row-Internal Fluid Return for Boundary Layer Control

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Solution Overview

Problem

The aerodynamic loadability and efficiency of fluid flow machines like blowers, compressors, and pumps are limited by the growth and separation of boundary layers near the casing wall, with existing solutions providing only limited and complex methods to influence these layers.

Innovation Solution

A blade row-internal fluid return arrangement with fluid offtake and supply openings in the sidewall, connected by a short fluid return path, optimizing flow behavior by positioning offtake points at the blade trailing edge and supply points near the suction side, allowing for efficient fluid recirculation without relative movement between blades and the sidewall.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If fluid is removed from a location with higher energy level and returned to a downstream location, then boundary layer influence is achieved, but efficiency is impaired due to repeated work application and high pressure losses in long transfer passages

Engineering Contradiction:

Improveboundary layer control effectivenessVSAvoidefficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The fluid return arrangement is segmented into multiple distributed openings (of take openings and supply openings) along the blade row span, rather than using single centralized openings. This segmentation allows localized boundary layer control at multiple positions while minimizing the length of return passages, thereby reducing pressure losses and maintaining efficiency while achieving effective boundary layer influence.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The invention transitions from traditional axial or radial fluid transfer to a circumferential dimension by positioning of take and supply openings on opposite sides of the blade row in the circumferential direction. This dimensional change enables short return passages that bypass the long axial or radial transfer paths, significantly reducing pressure losses while maintaining boundary layer control effectiveness.

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If complex boundary layer flow phenomena are addressed using conventional methods, then some influence on wall boundary layers is achieved, but device complexity increases and practical applicability is restricted

Engineering Contradiction:

Improveboundary layer influenceVSAvoidcomplexity of fluid return arrangement

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The fluid return arrangement is merged with the existing blade row structure by integrating of take and supply openings directly into the blade row components (such as the rotor drum or stator housing). This merging eliminates the need for separate, complex external fluid transfer systems and auxiliary units, thereby reducing device complexity while maintaining boundary layer influence capability.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The blade row structure itself serves the dual function of both aerodynamic work and fluid return transport. The of take and supply openings are positioned such that the blade row's own structure provides the return passage, making the system self-sufficient and eliminating the need for external auxiliary units, thus reducing overall system complexity.

Inventive Principle:

Principle #25Self-service

3Reliability

If fluid return passages are made long to connect different blade rows, then boundary layer control is achieved, but pressure losses increase significantly

Engineering Contradiction:

Improveboundary layer controlVSAvoidpressure losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

Fluid is of taken from the high-energy region at the blade trailing edge or pressure side and immediately returned to the suction side within the same blade row's circumferential span, rather than transporting it axially to downstream blade rows. This preliminary action within the current blade row eliminates the need for long axial transfer passages, significantly reducing pressure losses while maintaining effective boundary layer control.

Inventive Principle:

Principle #10Preliminary action

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 achieves improved flow characteristics and increased efficiency, reducing constructional and cost investments, with potential efficiency gains of up to 1% and a more space-saving design.

Implementation Method 1

at least one fluid offtake opening (9) and at least one fluid supply opening (10) which are arranged in the sidewall (1) in the area of a blade row (6, 7) and which are connected by at least one fluid return path (11)

Methodology Applied

Scientific EffectFluid recirculation:

Data Source

PatentUS8043046B2Fluid flow machine with blade row-internal fluid return arrangement

Publication Date: 2011.10.25 ROLLS ROYCE DEUT LTD & CO KG

AI summary

A fluid flow machine has a flow path (2) which is confined by at least one wall, on which at least one row of blades (6, 7) is fixedly mounted. At least one fluid offtake opening (9) and at least one fluid supply opening (10), which are connected by at least one fluid return path (11), are arranged in the wall in an area of a blade row (6, 7), with a circumferential extension of the fluid supply opening (10) being less than a distance between two adjacent blades.