The Plasma Wind Tunnel Complex at Syracuse, Italy has
The Syracuse Plasma Wind Tunnel (PWT) is the world's largest and more powerful hypersonic, high enthalpy, low pressure arc-jet facility in operation. It was built in the framework of the ESA program Hermes and is operational since 2012. The design and engineering of the Syracuse facility represent the state of art of the arc-jet technology.
The Syracuse facility has been realized to simulate the extreme heat flux and pressure conditions to which are exposed space vehicles re-entering in Earth's atmosphere. The main goal of the facility is to qualify large scale test articles up to 600 mm in diameter, of Thermal Protection Systems (TPS), Hot Structures and Payloads of space re-entry vehicles. The engineering activities that lead from the test requirements up to the test execution and evaluation of results are extremely complicated and multidisciplinary.
It is powered by an arc heater of 70 MW maximum electrical power and it is able to generate a plasma jet of up to 2 meters of diameter for a test duration of up to 30 minutes.
The test gas is a mixture of Air and Argon with a maximum mass flow rate of 3.5 kg/s. Inside the arc, the compressed gas is heated up to plasma temperatures in the range of 2,000-10,000 K.
The plasma flow is accelerated to hypersonic speed through a converging-diverging conical nozzle. There are five different nozzle configurations available with exit diameters ranging from 187 mm (for super-orbital re-entry simulation) to 1950 mm, in order to achieve the desired flow condition.
A Model Support System injects the test article in the plasma jet inside the Test Chamber, a vertical cylindrical vessel with an overall height of 9 m and an inner diameter of 5 m. The hypersonic jet is convoyed to a long Diffuser where the transition from hypersonic to subsonic flow takes place and then is cooled by a gigantic Heat Exchanger. A Vacuum System generates the required vacuum conditions in the upstream test leg. The system consists of steam ejectors that use as motor fluid up to 100 t/h of high pressure water steam (30 bar and 250°C). Before the process gas is ejected into the atmosphere, it is scrubbed by chemicals in the DeNOx System in order to remove the Nitrogen Oxides produced in the hypersonic-subsonic transition.