Monthly Archives: June 2020

Global Wind Day

To celebrate Global Wind Day, Mechanical Engineering Graduate, Jenny tells us about her experience of designing and creating a wind turbine.

Did you know that the UK now generates twice as much energy from wind as coal? Or that wind turbine blades are usually 60 metres long?! That’s roughly the same length as six double-decker buses!

As we’re all trying to combat climate change, the rise of wind power is excellent news as they generate ‘clean’ energy – wind turbines do not produce any harmful greenhouse gases or pollutants once they are built thanks to their clever design! Wind turbines might seem like a modern invention, but humans have been using wind power for over two thousand years. In the past, farmers in Iran and China would use windmills to grind grains for people to eat. The first wind turbine to generate electricity was invented in 1888 and it had 144 wooden blades!

You might be wondering – why do modern wind turbines always have three blades? There’s actually lots of science behind this. As the number of blades increases, so does the ‘drag’ – where force from the air slows it down. Ideally, wind turbines would only have one blade, as this would generate the most electricity, however it would be extremely unstable. Turbines with three blades are a compromise – the least blades possible to produce a stable turbine that won’t fall apart once it starts spinning!

Wind turbines work by generating electricity as they spin – the kinetic energy from the rotating blades powers a generator which turns the kinetic energy into electricity that we can use to power our homes. This is one of the benefits of wind power – it gives us a great way to generate electricity without burning fossil fuels, which emit gases which contribute to global warming.

As a mechanical engineering student, I learned a lot about wind turbines in my first year of University. My first group project was to take apart an old computer with my team, and re-build it into a small wind turbine. We were able to test our turbine in a ‘wind tunnel’ – where fast-moving air is channelled towards an object to see how it will perform in real life. Engineers use wind tunnels to test devices they’ve made for safety and performance. It’s not just wind turbines that get tested in wind tunnels though – engineers test cars, planes and even spacecrafts to see how they behave!

Jenny with her project team and their wind turbine

At university we learned about the different kinds of wind turbines. Most of the turbines that you’ve seen in real life are a specific type of turbine called a ‘HAWT’ – a ‘Horizontal Axis Wind Turbine’. They have three, long thin rotating blades. However, there’s a whole other category of wind turbines that you might not know existed – they’re called ‘VAWT’s (Vertical Axis Wind Turbines), such as the one shown below. VAWT’s rotate around a centre axis, like a merry-go-round. They are used when winds are too turbulent for regular (horizontal axis) turbines.

A Vertical Axis Wind Turbine (VAWT)

To celebrate ‘Global Wind Day’ on June the 15th, a great experiment to do at home would be to create your own wind turbine from paper or wooden sticks and test it out in front of a desk fan. Why not try out different blade shapes to see which ones work the best? How about trying a different number of blades? How does that affect how your turbine spins?

STEM Students answer Children’s Questions #8

When visiting schools and museums our Street Scientists often get asked a variety of questions from curious children. Here are the answers to some of our favourite questions!

This week, we’re answering questions on Marine Biology and Oceanography, ahead of World Ocean Day next Monday.

How do they (fish) breath under water?

-asked by Maisie, 9, from Kells Lane Primary School

Fish can breathe under water because they have lungs that are adapted to work under water. These are called gills. Gills are feathery organs full of blood vessels, fish use them to take up oxygen that is dissolved in the water. Oxygen is taken up through the thin walls of the gills and the travels into the cells in the body. However, there are some mammals that are mistaken as fish, such as whales and dolphins. They are just like us and they need to breathe air to survive. Therefore, we often see them swimming into the surface and take up some oxygen from the air.
– Aurelia, Dentistry Student

What is the fastest fish in the world?

-asked by Isobel, 11, from Marden Bridge Middle School

The fastest current known fish is the sailfish, it can swim at speeds of up to 68 miles per hour which is around the same speed as cars travel up the motorway! 
– Demi, Marine Biology Student

How are waves formed?

-asked by James, 10, from Ravenswood Primary School

Most waves are formed by wind blowing over the top of the sea. The stronger the wind the bigger the waves! However there are a couple of different types of wave that aren’t formed by the wind for example the tides are actually a form of wave, which are formed by the gravitational attraction of the sun and the moon on the water. Also tsunamis are a type of wave that is formed by under water earthquakes or eruptions!  
– Demi, Marine Biology Student

How big is the sea?

-asked by Iyla, 7, from Grace Darling Primary School

The sea covers about 71% of the world’s surface and although it is all connected it is usually split into 5 oceans called: The Pacific, the Atlantic (this is the ocean the UK is in), the Indian, the Antarctic and the Arctic ocean. All combined that is 1.3 billion cubic km of water, that’s about 3.47 Quadrillion swimming pools which is 462,667 swimming pools for every person living on the planet! The Atlantic ocean where we are is the second biggest ocean in the world and if you tried to swim from here to America it would take you 50 days if you swam non stop. The deepest bit of the ocean is called the Mariana trench and it is 11,034 metres deep that’s more than mount Everest which is the highest mountain in the world, it’s so deep that only 3 people have ever been there (that’s fewer than have been to the moon). 
-Lizzie, Biology Student

#TryThisTuesday: Colourful Flower Bouquet

Last week, Street Scientist, Ailie, showed us how to make a colour wheel with kitchen roll. Now we’re going to use that same technique to create a colourful bunch of paper flowers.

How can we use the process of capillary action, and the coloured water we made last week, to do something creative? First, you need to make 6 flower heads out of kitchen roll by folding and cutting as below.

  1. First fold the sheet in half to make a rectangle.
  2. Fold the rectangle in half to make a square.
  3. The fold the square in half diagonally to make a triangle.
  4. Fold the triangle in half again.
  5. Cut the top of the small triangle into a round petal shape
  6. Unfold the sheet to reveal your flower.
  • Cut another sheet in half and twist it up to form a stalk. Then pinch the end of your flower head and tape the stalk to the flower.
  • Place the stem of each flower into one of the cups of coloured water from earlier. Put something underneath the flower heads to soak up any extra water, or do it outside if you can.
  • Come back in an hour and the water should have moved, by capillary action, throughout the whole flower. You can now remove the stems from the cups and leave them to dry.
  • Scrunch all the dried flowers you’ve made together, tape around the top of the stalks, and you’ve made a beautiful multicoloured bouquet.