Air Multiplier Cooling Structure for Low-Noise Transformer Airflow

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Solution Overview

Problem

Existing cooling systems for electric induction devices like transformers and shunt reactors are inefficient, noisy, and require high power consumption, with conventional fans producing turbulence and maintenance issues.

Innovation Solution

An airflow generator with a ducted fan and an air multiplier having a specific aerodynamic profile that efficiently pressurizes airflow, reducing power consumption and noise, while minimizing turbulence and maintenance needs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Object-affected harmful factors

If conventional bladed fans are used for transformer cooling, then cooling capability is achieved, but noise is high, structure is complex, and maintenance is difficult

Engineering Contradiction:
ImprovenoiseVSAvoidstructure complexity
Core Design Contradiction:
Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The patent replaces conventional bladed fans with an air multiplier device that uses aerodynamic principles instead of mechanical blades. The air multiplier creates a jet stream that entrains surrounding air through the Coandă effect, eliminating the need for complex bladed mechanisms while reducing noise and simplifying structure.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces a fluid conduit as an intermediary component that connects the ducted fan to the air multiplier, optimizing airflow transmission. This intermediary structure allows efficient pressure transmission while simplifying the overall system architecture compared to direct fan-to-radiator connections.

Inventive Principle:
Principle #24Intermediary (Mediator)

2Device complexity

If natural convection is used for transformer cooling, then structure is simple, but cooling capability is insufficient for high-power transformers

Engineering Contradiction:
Improvestructure simplicityVSAvoidcooling capability
Core Design Contradiction:
Device complexityVSProductivity

Solution Approach 1:

The air multiplier device utilizes the jet stream it generates to automatically entrain and accelerate surrounding ambient air through the Coandă effect. This self-service mechanism multiplies the airflow without requiring additional power input, achieving enhanced cooling capability while maintaining structural simplicity.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent employs pneumatic principles through the air multiplier device, which generates a controlled jet stream that interacts with ambient air through fluid dynamic effects. This pneumatic approach provides forced convection capability suitable for high-power transformers while keeping the structure relatively simple.

Inventive Principle:
Principle #29Pneumatics and hydraulics

3Productivity

If large fans are used to increase airflow rate, then cooling efficiency improves, but power consumption increases

Engineering Contradiction:
Improveairflow rateVSAvoidpower consumption
Core Design Contradiction:
ProductivityVSUse of energy by moving object

Solution Approach 1:

The air multiplier device uses the kinetic energy of its own jet stream to automatically draw in and accelerate surrounding ambient air. This self-service mechanism creates a multiplicative effect where a small amount of powered air generates a much larger total airflow, significantly reducing power consumption compared to conventional fans.

Inventive Principle:
Principle #25Self-service

Solution Approach 2:

The patent changes the fundamental parameter of airflow generation from direct mechanical displacement (conventional fans) to aerodynamic entrainment (air multiplier). This parameter change allows achieving higher airflow rates with lower power input by utilizing fluid dynamic effects rather than direct mechanical force.

Inventive Principle:
Principle #35Parameter changes

4Ease of operation

If conventional fans are used for cooling, then cooling function is provided, but the system is heavy and difficult to maintain

Engineering Contradiction:
Improvemaintenance easeVSAvoidsystem weight
Core Design Contradiction:
Ease of operationVSWeight of stationary object

Solution Approach 1:

The patent replaces heavy mechanical fan assemblies with a lighter air multiplier device based on aerodynamic principles. This substitution eliminates complex mechanical components such as blades, motors with heavy housings, and associated mounting structures, thereby reducing overall system weight and simplifying maintenance requirements.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

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 airflow generator achieves efficient cooling with reduced power consumption, lower noise, and extended service life by enhancing airflow without internal edges causing turbulence.

Implementation Method 1

The air multiplier comprises an aerodynamic profile defined by a cross-sectional profile shape swept along a profile path... The fan provides an airflow into the air multiplier... a much larger amount of air than the amount of air supplied by the fan, is discharged towards the oil-to-air heat exchanger

Methodology Applied
Scientific EffectCoandă effect: Coanda Effect

Implementation Method 2

The cooling process typically uses natural convection or forced convection to move ambient air past the radiator... The fan provides an airflow into the air multiplier. The ducted nature of the fan enables it to efficiently pressurize the fluid conduit.

Methodology Applied
Scientific EffectForced convection: Forced Convection

Data Source

PatentEP4549745B1An airflow generator
Publication Date: 2026.04.29 HITACHI ENERGY LTD
  • EP4549745B1 patent drawingFigure 1
  • EP4549745B1 patent drawingFigure 2~3
  • EP4549745B1 patent drawingFigure 4~6

AI summary

An airflow generator (1) comprising: an electrically powered ducted fan (2) provided with an inlet (3) and an outlet (4), a fluid conduit (5); and an air multiplier (6) for discharging air along a first axis (A), said air multiplier (6) comprising an inlet (8) and an outlet (9), said fluid conduit (5) fluidly connecting the outlet (4) of the ducted fan (2) to the inlet (8) of the air multiplier (6). The air multiplier (6) comprises an aerodynamic profile defined by a cross-sectional profile shape (P) swept along a profile path (PA), wherein the cross-sectional profile shape (P) comprises outer wall portions defining an inner space (S) and defining said outlet (9) which fluidly connects the inner space (S) to ambient air. The outer wall portions comprise a rounded leading portion (P1) for facing incoming ambient air moved by the air multiplier (6), an elongated first side portion (P2) extending from the leading portion (P1) towards a trailing portion (PT) of the profile shape (P), and an elongated second side portion (P3) extending from the leading portion (P1) towards the trailing portion (PT) of the profile shape (P), wherein the first side portion (P2) extends non-overlapping with respect to itself, wherein the second side portion (P3) extends non-overlapping with respect to itself, and wherein the first side portion comprises a curved end portion (P4) extending along said first axis (A) past a free end (E) of the second side portion (P3).