Shower head and method of operation to produce a suspension of water droplets in air

A shower apparatus (1) including:

• an air supply means (2),
• a water supply means (3), and
• a shower head (10), the shower head including at least one chamber (11);
• the chamber being defined by a chamber wall (12) and extending along a central chamber axis (Xc), from an air inlet (13) and a water inlet (14) at a first end of the chamber, to an outlet (16) opening at a second end of the chamber;
• the air inlet (13) being arranged around the water inlet (14);
• the chamber having a length Lc along the chamber axis from the water inlet (14) to the outlet opening (16);
• the water supply means being arranged for connection to a supply of water having a density ρw, surface tension σw and dynamic viscosity μw to eject the water at a velocity uw from the water inlet (14), axially centrally into the chamber along the chamber axis (Xc), as a column of water (41) with a diameter dw;
• the air supply means being arranged to supply an annular flow of air (51) at a density ρa and a velocity ua from the air inlet (13) into the chamber (11) around the water column (41);
• the flow of air (51) being arranged to destabilise the water column (41) within the chamber so as to break the water column into a shower of droplets suspended in the air flowing from the outlet opening (16);
• wherein
• an aerodynamic Weber number is defined as
• Wea=(ρa·(ua−uw)2·dw)/σw
• and a liquid Reynolds number is defined as
• Rew=(ρw·uw·dw)/μw
• and wherein
• ua>uw and
• 5≤Wea≤55 and
• 3000≤Rew≤10000 and
• the water column (41) is contained within a dimensional envelope (61) defined as a surface of rotation about the chamber axis (Xc), and
• the dimensional envelope (61) is spaced apart radially inwardly from the chamber wall (12) at all points along the length Lc of the chamber, and
• the water column (41) is continuous for the length Lc of the chamber.