# What type of fountain nozzle ejects water in an oval shape?

I have seen one video about fountains, and there are some kind of nozzles. What type of nozzle is used in the fountain shown below?

As can be seen in the photo, the fountain nozzle causes an oval shape to form from the water cascading back down.

• A lot more comes into play in this type of fountain design than just the nozzle shape. A few arguably more important variables are: flow rate, depth of the nozzle under the water surface, and size of the container. Aug 17, 2015 at 13:25

## 3 Answers

The only way to achieve a curved water stream without an external force* is to change the direction it is being sprayed. The way the effect below is accomplished is that the nozzle rotates from a vertical to a horizontal angle, which causes the illusion that the stream is curving.

The oval shape is created by a trumpet-type nozzle:

Increasing the deflection and reducing pressure causes the flow to bulge outward and not go as high. The fountain then just oscillates between a "high and narrow" stream, and a "medium height and wide" stream. The resulting shape then also oscillates, making it look like an oval that collapses in on itself and then reemerges.

This page has some more sample pictures. Those are composed from multiple individual nozzles, but the same principle applies to e.g. trumpet nozzles, which create a 3-dimensional flow from one nozzle.

*Gravity is one force, but will always accelerate downward causing a parabola shape. Wind is another, but again it acts in one direction and is not predictable/constant. Surface tension can actually produce a spherical curve like that with a water bell, but requires laminar flow and the water in your case looks rather turbulent. Also it wouldn't change shape.

The fountain you're asking about (and yes, I realize this thread is years old...) is at Harborside Fountain Park in Bremerton, WA. That effect is created with air-fired fountain jets. Think of a compressed-air potato cannon, set vertically, with the pipe filled with water. Air is rapidly injected into the base of the pipe, pushing out a big slug of water. If the pipe is tall and narrow, or has a small nozzle orifice, and high pressure is used, these will shoot very high (like the hyper shooters in the Bellagio fountain). In Bremerton, the pipes are large diameter, so you're pushing up a massive volume of water, at a fairly low pressure (as opposed to high-pressure at Bellagio). When the slug of water blasts into the open air it expands outward creating the exploding egg effect.

This type of flow is called a water bell, or at least the laminar version of it is. Here's the website of a manufacturer of these sorts of nozzles.

Also, G. I. Taylor wrote a paper on the various phenomena involved with water bells. (I have not read it, but someone reading this may find it to be interesting.)

• sorry dude those nozzles are not water bell kind because the waters wall change with motor power and is rise up and down along the time. this photo is only one part of a video. Aug 18, 2015 at 12:01
• @soheilpaper don't expect people to read your mind. As I commented on your question, describe what you want. Nowhere in your question do you mention that things change.
– hazzey
Aug 18, 2015 at 13:54
• There are a number of ways to make a pulsing fountain, so the nozzle could be the same. If you could link to the video, I would be interested. Aug 18, 2015 at 23:23