Turbomachine Blade Ring Discontinuous Gap Flow Control

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Solution Overview

Problem

Turbine diffusers face challenges in achieving maximum pressure recovery due to flow separation, which leads to inefficiencies and structural issues, and existing methods to prevent separation either reduce efficiency or increase costs.

Innovation Solution

A device with a blade ring featuring a discontinuous gap height around its circumference, increasing local gap flow to energize the boundary layer and stabilize the flow, thereby preventing separation and allowing for shorter diffuser designs with improved efficiency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stress or pressure

If the diffuser opening angle is increased to achieve maximum pressure recovery, then pressure recovery is improved, but flow separation occurs leading to backflow and reduced efficiency

Engineering Contradiction:

Improvepressure recoveryVSAvoidflow stability

Core Design Contradiction:

Stress or pressureVSReliability

Solution Approach 1:

The patent applies periodic action by introducing gap flow at regular intervals through circumferentially spaced gaps in the blade ring. This periodic injection of high-energy flow into the boundary layer prevents flow separation and stabilizes the diffuser flow, enabling higher opening angles without flow reversal

Inventive Principle:

Principle #19Periodic action

Solution Approach 2:

The patent uses gap flow as an intermediary substance to transfer energy from the main flow to the boundary layer. The gap flow acts as a mediator that energizes the boundary layer and prevents separation, allowing the diffuser to operate at optimal opening angles without flow instability

Inventive Principle:

Principle #24Intermediary (Mediator)

2Reliability

If passive flow energization methods are used to prevent flow separation, then flow stability is improved, but additional losses occur in stable operating ranges

Engineering Contradiction:

Improveflow stabilityVSAvoidflow losses

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The patent applies dynamics by making the flow control mechanism adaptive rather than static. The gap flow is dynamically activated only when needed (in unstable operating ranges) and can be adjusted in magnitude, allowing the system to maintain high efficiency in stable ranges while providing stabilization when required

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

The patent changes the parameter of gap flow rate to control boundary layer energization. By adjusting the gap flow rate based on operating conditions, the system can prevent flow separation when needed while minimizing energy losses during stable operation

Inventive Principle:

Principle #35Parameter changes

3Reliability

If active flow control with working fluid injection is used to prevent flow separation, then flow stability is improved, but power output and efficiency are reduced

Engineering Contradiction:

Improveflow stabilityVSAvoidpower output

Core Design Contradiction:

ReliabilityVSPower

Solution Approach 1:

The patent applies self-service by using the turbomachine's own gap flow (which would otherwise be waste) to energize the boundary layer and prevent flow separation. This eliminates the need for external working fluid injection, maintaining power output while achieving flow stabilization

Inventive Principle:

Principle #25Self-service

4Reliability

If diffuser length is increased to prevent flow separation, then flow stability is improved, but manufacturing costs increase

Engineering Contradiction:

Improveflow stabilityVSAvoidmanufacturing cost

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent changes the parameter of diffuser geometry by introducing circumferential gaps in the blade ring. This allows the diffuser to be shorter while maintaining flow stability through periodic boundary layer energization, reducing manufacturing costs without sacrificing reliability

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 enhances pressure recovery, reduces the risk of flow separation, and minimizes mechanical stresses, leading to more efficient and cost-effective turbomachine operation by maintaining a stable boundary layer and reducing backflow areas.

Implementation Method 1

energize the boundary layer and stabilize the flow, thereby preventing separation

Methodology Applied

Scientific EffectBoundary layer: Boundary Layer

Implementation Method 2

flow separation can arise because the boundary layer at the diffuser wall loses increasing energy with increasing length

Methodology Applied

Scientific EffectFlow separation: Flow Separation

Data Source

PatentEP3204614B1Device for influencing the flow in a turbomachine

Publication Date: 2022.01.26 UNIVERSITAT STUTTGART

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AI summary

The invention relates to a device (10) for influencing the flow in a turbomachine (1), which device comprises a housing (1a) and at least one blade ring (9), which has a plurality of blades (15) and rotates within the housing (1a). There is a gap (11) between the housing (1a) and the blade ring (9), which gap is continuous in the axial direction (x) and has a discontinuous height around the periphery of the blade ring (9). By means of the gap, the gap flow over the blade ring (9) is locally increased and the flow in the boundary layer with respect to the housing (1a) is stabilized.