Cranfield University Icing Tunnel
Our Icing Tunnel facilities are unique, comprising arguably the largest icing tunnel in the UK and the largest droplet tunnel for icing studies in the world. Opened by HRH Duke of Kent, the facilities have been the focus of a wide range of international research and development work.
Water droplets in clouds can cool well below freezing point and yet remain liquid. It is often only when they touch a solid object that they freeze. Aircraft, tall buildings, wind turbines and even crops can be greatly affected by the ice which forms on them due to windborne droplets. Ice growth rates can be over 1 mm per minute and the ice layer is often highly irregular and can give rise to major changes in the aerodynamic qualities of both natural and man-made structures. The weight of ice can also cause problems, especially on rapidly rotating parts such as helicopter blades and aero gas turbine engine fans. When ice fractures or warms up and falls away from whatever it has grown on, further problems can arise. Rotating parts can become dangerously out of balance and ice fragments falling or blowing around can cause mechanical damage and blockages.
About the facility
In our main icing tunnel, we are able to create realistic icing conditions at a component level, providing information on how well ice protection equipment is working and on the adhesion of ice to a given material. We collect information which helps to support the development of ice accretion modelling tools so that designers of aircraft, their engines and other exposed equipment can assess the likely impact of ice accretions on the performance of their devices.
In our droplet tunnel, we can examine how a single water droplet behaves as it strikes a surface at speed. This is our microscope on the icing process. It allows us to see the change in shape of droplets in an air flow as they move close to a solid surface and how they splash and spread when they strike the surface. We see how the water which does not freeze immediately flows and gathers as rivulets, attached droplets or forms a film of water. All this helps us to understand the icing process and find better ways to model it. It also helps us look into the potential of how highly engineered surfaces can be used to control ice growth.