Centrifugal Compressor Forward Thrust and Cooling Apparatus

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Solution Overview

Problem

Existing gas turbine engines with centrifugal compressors face challenges in maintaining optimal forward thrust on the impeller to minimize blade tip clearance and ensure efficient turbine cooling, as conventional methods have limitations in achieving sufficient forward rotor thrust and efficient air cooling due to design constraints and high airflow losses.

Innovation Solution

The apparatus includes an annular centrifugal compressor impeller with an impeller bleed system that directs aft bleed flow into a pressurized annular cavity, utilizing conical diffusion holes and metering holes to create a positive axial thrust, and a cooling air bleed system with minimal turning losses to efficiently cool turbine components.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Force

If the inner radius of the swirl plate is increased to increase forward rotor thrust, then forward rotor thrust is improved, but windage losses increase and the design becomes more complex due to the need for a windage shield

Engineering Contradiction:

Improveforward rotor thrustVSAvoidwindage losses

Core Design Contradiction:

ForceVSLoss of energy

Solution Approach 1:

The invention extracts the windage shield requirement by using a different approach to generate forward thrust. Instead of increasing swirl plate inner radius which requires a windage shield, the patent uses a vane assembly with adjustable vanes to create thrust while maintaining clean air flow paths for turbine cooling.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The vane assembly serves multiple functions: it generates forward rotor thrust through adjustable vanes while simultaneously allowing clean air to be bled for turbine cooling. This multi-functionality eliminates the need for separate windage shields and clean air bleed paths.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Temperature

If clean air is used for turbine cooling, then turbine cooling efficiency is improved, but the ability to increase forward rotor thrust is limited due to windage shield requirements

Engineering Contradiction:

Improveturbine cooling efficiencyVSAvoidforward rotor thrust capability

Core Design Contradiction:

TemperatureVSForce

Solution Approach 1:

The invention merges the forward thrust generation and turbine cooling functions into a single integrated system. The vane assembly creates thrust while the same structure allows clean air to be bled directly for turbine cooling, eliminating the trade-off between the two functions.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The vane assembly acts as an intermediary that enables both thrust generation and clean air bleed for cooling. The adjustable vanes create the necessary flow patterns to generate thrust while maintaining a separate clean air path to the turbine cooling system.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Stress or pressure

If the swirl plate inner radius is increased to reduce windage losses, then air static pressure and piston area increase, but practical design limits are reached

Engineering Contradiction:

Improveair static pressureVSAvoidswirl plate design complexity

Core Design Contradiction:

Stress or pressureVSDevice complexity

Solution Approach 1:

The invention uses adjustable vanes in the vane assembly that can be dynamically positioned to optimize performance. This dynamic adjustment allows the system to achieve optimal air static pressure and piston area without being constrained by fixed swirl plate radius design limits.

Inventive Principle:

Principle #15Dynamics

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 effectively maintains optimal impeller blade tip clearance, enhances forward rotor thrust, and provides efficient turbine cooling with reduced airflow losses, improving fuel efficiency and preventing potential engine damage from rotor thrust imbalances.

Implementation Method 1

conical diffusion holes in the forward end wall

Methodology Applied

Scientific EffectDiffusion: Diffusion

Implementation Method 2

annular centrifugal compressor impeller

Methodology Applied

Scientific EffectCentrifugal force: Centrifugal Force

Data Source

PatentUS8147178B2Centrifugal compressor forward thrust and turbine cooling apparatus

Publication Date: 2012.04.03 GENERAL ELECTRIC CO

AI summary

A gas turbine engine centrifugal compressor axial forward thrust apparatus bleeds impeller tip aft bleed flow from between an annular centrifugal compressor impeller of a high pressure rotor and a diffuser directly downstream of the impeller. The apparatus then uses the aft bleed flow to pressurize an annular cavity extending radially between an inner combustor casing and the rotor and extending axially between forward and aft thrust balance seals. Forward and aft thrust balance lands are in sealing engagement with the forward and aft thrust balance seals on the high pressure rotor respectively. An annular stator plenum in fluid communication with the annular cavity is bounded in part by a forward end wall having conical diffusion holes therethrough which may be axially or circumferentially or axially and circumferentially angled. The forward thrust balance seal may be on an aft conical arm of the impeller.