Why install a ball on the roof? Surprisingly, so many people don't know

Tech 2023-05-04 21:48:28 Source: Network

Audit experts:Luo HuiqianAssociate Researcher, Institute of Physics, Chinese Academy of SciencesDo you have any friends like me? Every time I look at the scenery on the rooftop, my attention is attracted by the constantly rotating metal balls on the roof. Are everyone curious about these metal balls that frequently appear on rooftops or on the roofs of factories? What are these round and rolling guys used for, and why do they always appear on the roof?Today, let me take you all to understand the past and present lives of these little things

Audit experts:Luo Huiqian

Associate Researcher, Institute of Physics, Chinese Academy of Sciences

Do you have any friends like me? Every time I look at the scenery on the rooftop, my attention is attracted by the constantly rotating metal balls on the roof. Are everyone curious about these metal balls that frequently appear on rooftops or on the roofs of factories? What are these round and rolling guys used for, and why do they always appear on the roof?

Today, let me take you all to understand the past and present lives of these little things.

Unpowered hood

To be honest, because these things always "roll" on the roof, the editor had always referred to them as "silver rolling balls" before. As for their real names, I just learned from the worker a few days ago that the names of these guys areUnpowered hoodThe reason why they are called 'unpowered' is not because they do not require any power, but rather because they do not require additional electrical energy and can be driven solely by natural wind.

Unpowered hood

Source | Sohu website

So, what are they used for?Unpowered hood

Unpowered hood

Next, let's explore what kind of internal structure lies beneath their round appearance.

Unpowered hoodThe wind blade is the most important component of the entire hood.

Internal structure of the hood

| @Unpowered hood

The round exterior of the hood has a considerable space inside, with two brackets hidden inside. Among them, the upper bracket is an aluminum bracket, and the lower bracket is a nylon bracket. They mainly play a supporting role, effectively improving the overall mechanical strength and flexibility of the hood.

The stainless steel material used in making the hood eliminates the need for us to consider the issue of corrosion in the hood. At the same time, the stainless steel material also greatly improves the mechanical strength of the hood, ensuring its sustainable and stable operation.

In short, after precise design by experts, the hood can not only be waterproof, fireproof, explosion-proof, and windproof, but also effectively prevent foreign objects from falling into the device, greatly improving the service life of the hood.

Unpowered hood

After understanding the internal structure, another issue arose before us. How does this seemingly simple hood work?

Unpowered hood

The range hood in the kitchen

Source | Zhihu @ What is it worth buying for a straight man

If there is natural wind outside, the hood can rotate under the force of wind, and the centrifugal effect during the rotation can reduce the surrounding air pressure, forming a negative pressure zone, where the air pressure inside the hood is lower than the indoor air pressure.Due to the existence of pressure difference, the air flowing in parallel directions indoors will partially transform into air flowing vertically from bottom to top, thus pumping the stale air inside the house to the outside.

As for the rate of air extraction, it mainly depends on the size of natural wind. In this case, the working principle of the hood is similar to that of a range hood, except that the range hood drives the internal fan to rotate by consuming electrical energy, thereby forming a negative pressure zone.

A towering chimney

Source | Baidu Baike

If there is no horizontal wind outside, the thermal updraft formed solely by relying on the indoor air temperature being higher than the outdoor air temperature(Similar to the principle of a chimney)It can also drive the hood to rotate, and the centrifugal effect generated by the rotation will form a negative pressure zone, further accelerating the flow rate of the upward airflow, thereby accelerating indoor and outdoor air circulation.

A small hood has many benefits

fromFrom an environmental perspectiveGenerally speaking, the hood does not produce any pollution during operation and emits very little noise, making it an environmentally friendly and practical product.It can also improve the lighting environment of users' homes. The hood installed on the roof can provide light through the gaps between the fan blades, and a bright home environment can also improve our mood throughout the day.

fromOne installation requires no maintenance, reducing installation costs and electricity bills.

fromSafety perspectiveGenerally speaking, a hood can also ensure the personal safety of users in special circumstances.from

Unpowered hood

Source | Zhihu @ Homestead Decoration Station

to make a long story short,Unpowered hoodUnpowered hood

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Does not represent the position of the Institute of Physics of the Chinese Academy of Sciences

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Source: Digital Beijing Science Center

Editor: Xiao Fan

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