Impeller Shroud Variable Gap for Leakage and Shear Control

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Solution Overview

Problem

Existing deaerators in rotational equipment, such as gas turbine engines, face challenges with leakage around the impeller rotor, which affects efficiency and leads to increased fluid shear and impeller rotor power demand.

Innovation Solution

The design incorporates a shroud with varying gap dimensions and protrusions to minimize fluid leakage and shear, featuring a static structure with a cavity surface and an impeller rotor with a vane structure and seal elements, including a base and protrusions that project towards the static structure, and grooves that adjust during different operational modes to optimize fluid flow.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If a fixed gap is maintained between the impeller rotor and static structure, then manufacturing and operation are simplified, but fluid leakage increases and efficiency decreases

Engineering Contradiction:

Improvefluid leakageVSAvoidgap configuration

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

The gap between the impeller rotor shroud and static structure is configured to vary along the axial direction, transitioning from a first gap dimension at the upstream end to a second gap dimension at the downstream end. This dynamic gap configuration optimizes fluid flow control and reduces leakage while maintaining manufacturability.

Inventive Principle:

Principle #15Dynamics

Solution Approach 2:

Different regions of the gap have different dimensions tailored to local flow requirements. The upstream end has a larger gap to accommodate inlet flow conditions, while the downstream end has a smaller gap to reduce leakage and control outlet flow, optimizing performance at each location.

Inventive Principle:

Principle #3Local quality

2Loss of energy

If seal elements are added to reduce leakage, then fluid leakage decreases, but device complexity increases

Engineering Contradiction:

Improvefluid leakageVSAvoidseal element structure

Core Design Contradiction:

Loss of energyVSDevice complexity

Solution Approach 1:

A seal element comprising a flexible lip is positioned within the gap between the impeller rotor shroud and static structure. The lip flexes to maintain contact with the rotating shroud surface, creating an effective seal that reduces fluid leakage without requiring complex mechanical sealing systems.

Inventive Principle:

Principle #30Flexible shells and thin films

Solution Approach 2:

The seal element acts as an intermediary component between the rotating impeller rotor and the static structure, mediating the fluid flow path and preventing direct leakage while allowing rotational motion to continue uninterrupted.

Inventive Principle:

Principle #24Intermediary (Mediator)

Data Source

PatentEP4137221A1Variable gap between impeller rotor and static structure

Publication Date: 2023.02.22 PRATT & WHITNEY CANADA CORP

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AI summary

An assembly is provided for a turbine engine. This rotational equipment assembly includes a static structure and an impeller rotor (32) housed within the static structure. The impeller rotor (32) includes a vane structure (76) and a shroud (74). The shroud (74) circumscribes the vane structure (76). A gap is formed by and extends between the shroud (74) and the static structure. A dimension of the gap changes as the gap extends along the shroud (74). The dimension can be changed by a protrusion on and around the shroud or by a groove in the static structure .