Dyson unveils new ultra-quiet second-generation blade-less fans

UK inventor Sir James Dyson who invented the blade-less fans in 2009, will introduce the second generation of its fans, that are up to 75 per cent quieter than their predecessors (See; British innovator develops bladeless fan).

The fans would be offered complete with a remote control, a newly-introduced sleep timer and a choice of 10 airflow settings. Each fan can deliver cool air for up to nine hours at a stretch.

The noise reduction has been achieved with the aligned loop mechanism, which allows air to enter with less turbulence and subsequent noise.

The manufacturer makes use of a Helmholtz cavity in the base of each machine to eliminate irritating noise frequencies by dissipating sound waves.

The company first introduced the blade-less fan in 2009 after four years of development. It had launched the successful Airblade hand dryer three years earlier.

The fan draws air into an energy efficient brush-less motor near its base, and pushes it out at speed through a gap in the fan's ring, which is pushed over an airfoil-shaped ramp.

The flow draws in the surrounding air, which pushes out around 405 litres of air every second.

Each model undergoes 24 hour testing seven days a week to identify any potential problems.

The fan integrates a device that gets rid of tones in the 1000Hz range that are similar to the noise frequency of a mosquito.

According to the company's engineers this frequency was the one that irritated users of previous models so their aim was to make this particular noise ''totally inaudible''.

By reducing air turbulence and using ingenious, simple engineering principles like a Helmholtz cavity, Dyson engineers had targeted tones and reduced sound volume, making quiet fans with powerful airflow.

The fan is already one of Dyson's most successful ventures apart from its vacuum cleaners. According to Sir James, the company had invested around £40 million to produce the device.

The new fan range would be available in March. Prices would range from £219.99 (approximately Rs22,500) to £299.99.