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Simulation software from Ansys has been used in the design of the Dyson Air Multiplier fan, which is presented as a technical and stylistic re-imagining of the household fan.

To complement experimental testing and reduce development time for this fan, Dyson’s engineers used fluid dynamics software from Ansys to evaluate up to 10 different designs per day.

The idea for the Dyson Air Multiplier fan originated when the engineering team was testing the Dyson Airblade hand dryer, which works by generating a thin sheet of air moving at 400mph that pushes water off the user’s hands.

Observing the side effect that the sheet of air was dragging a considerable portion of the surrounding air with it, the team conceived a new idea: to produce a thin, high-speed sheet of air that drags surrounding air – a process known as inducement – through a fan.

Airflow leaving the product then drags along more flow – a process known as entrainment – and the Dyson Air Multiplier fan was the result.

This approach eliminated the need for the external blades of a conventional fan and provided a much smoother movement of air that is said to feel like a natural breeze.

For the new, bladeless fan, Dyson engineers developed a basic design concept in which air is drawn into the base of the unit by an impeller, accelerated through an annular aperture and then passed over an airfoil-shaped ramp that channels its direction.

The initial design had an amplification ratio – how much air is dragged along for each unit of primary flow – of six to one, which needed to be improved substantially for the finished product.

The company’s engineers used Ansys Fluent software to simulate fluid flow without the need for a physical prototype.

Being able to visualise fluid flow throughout the solution domain helped engineers to gain an intuitive understanding of the design, leading to rapid improvements.

The software’s ability to divide the domain into sub-domains substantially speeded up the process of making design changes.

For example, the sub-domains in and around the annular ring contained a very dense mesh to maximise accuracy in this critical area.

After making a change, the team had to remesh only the sub-domain that contained the change and, thus, the time for remeshing was reduced from over an hour to about 10min.

Each case was simulated as a 2D, steady-state, incompressible, turbulent air flow using the K-Epsilon turbulence model.

The software was consistent in predicting performance trends that were observed, which gave the engineering team confidence in the simulation results.

The next step was to evaluate a series of design iterations with the primary goal of increasing the amplification ratio to move the maximum amount of air possible for a given size and power consumption.

Dyson’s engineers quickly homed in on three dimensions as having major impact on performance: the gap in the annular ring, the internal profile of the ring and the profile of the external ramp.

The team was able to design and model up to 10 geometric variations of these dimensions in a single day and then compute the results in a batch overnight.

Another benefit of using fluid dynamics simulation was that the engineers were able to establish relationships between air velocity and delivered flow rate for various designs.

Over the course of the design process, Dyson’s engineers steadily improved the performance of the fan to the point that the final design has an amplification ratio of 15 to one – a 2.5-fold improvement over the six-to-one ratio of the original concept design.

The team investigated 200 different design iterations using simulation, which was 10 times the number that would have been possible had physical prototyping been the primary design tool.

Physical testing was used to validate the final design and the results correlated well with the simulation analysis.

Fluid flow simulation advances fan design

Simulation software from Ansys has been used in the design of the Dyson Air Multiplier fan, which is presented as a technical and stylistic re-imagining of the household fan.

To complement experimental testing and reduce development time for this fan, Dyson’s engineers used fluid dynamics software from Ansys to evaluate up to 10 different designs per day.

The idea for the Dyson Air Multiplier fan originated when the engineering team was testing the Dyson Airblade hand dryer, which works by generating a thin sheet of air moving at 400mph that pushes water off the user’s hands.

Observing the side effect that the sheet of air was dragging a considerable portion of the surrounding air with it, the team conceived a new idea: to produce a thin, high-speed sheet of air that drags surrounding air – a process known as inducement – through a fan.

Airflow leaving the product then drags along more flow – a process known as entrainment – and the Dyson Air Multiplier fan was the result.

This approach eliminated the need for the external blades of a conventional fan and provided a much smoother movement of air that is said to feel like a natural breeze.

For the new, bladeless fan, Dyson engineers developed a basic design concept in which air is drawn into the base of the unit by an impeller, accelerated through an annular aperture and then passed over an airfoil-shaped ramp that channels its direction.

The initial design had an amplification ratio – how much air is dragged along for each unit of primary flow – of six to one, which needed to be improved substantially for the finished product.

The company’s engineers used Ansys Fluent software to simulate fluid flow without the need for a physical prototype.

Being able to visualise fluid flow throughout the solution domain helped engineers to gain an intuitive understanding of the design, leading to rapid improvements.

The software’s ability to divide the domain into sub-domains substantially speeded up the process of making design changes.

For example, the sub-domains in and around the annular ring contained a very dense mesh to maximise accuracy in this critical area.

After making a change, the team had to remesh only the sub-domain that contained the change and, thus, the time for remeshing was reduced from over an hour to about 10min.

Each case was simulated as a 2D, steady-state, incompressible, turbulent air flow using the K-Epsilon turbulence model.

The software was consistent in predicting performance trends that were observed, which gave the engineering team confidence in the simulation results.

The next step was to evaluate a series of design iterations with the primary goal of increasing the amplification ratio to move the maximum amount of air possible for a given size and power consumption.

Dyson’s engineers quickly homed in on three dimensions as having major impact on performance: the gap in the annular ring, the internal profile of the ring and the profile of the external ramp.

The team was able to design and model up to 10 geometric variations of these dimensions in a single day and then compute the results in a batch overnight.

Another benefit of using fluid dynamics simulation was that the engineers were able to establish relationships between air velocity and delivered flow rate for various designs.

Over the course of the design process, Dyson’s engineers steadily improved the performance of the fan to the point that the final design has an amplification ratio of 15 to one – a 2.5-fold improvement over the six-to-one ratio of the original concept design.

The team investigated 200 different design iterations using simulation, which was 10 times the number that would have been possible had physical prototyping been the primary design tool.

Physical testing was used to validate the final design and the results correlated well with the simulation analysis.

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