Ventilation deflector: the aerodynamic solution for natural ventilation
A ventilation deflector is a specialised device designed to increase the efficiency of natural ventilation through the use of aerodynamic processes. It is mounted on top of ventilation ducts and chimneys and plays a key function in enhancing draught without the use of electrical power.
The basic principle of the deflector is the formation of a rarefaction zone when the air stream flows around its body. Due to its special form and construction, the device directs the wind in such a way as to accelerate its movement and reduce the pressure in the air outlet area. This helps to actively “pull” the exhaust air out of the ventilation ducts, improving air exchange in the room.
From a physical point of view, the deflector realises the Bernoulli effect: as the air flow speed increases, the pressure decreases. Inside the device, narrowed areas are created where the air speed increases and the pressure decreases. This leads to the creation of the ejection effect - drawing air from the ventilation duct. Devices with rotating elements, such as turbo deflectors, additionally use mechanical energy from the wind, increasing the overall performance, especially in low winds.
The construction of the deflector fulfils not only a functional but also a protective role. It prevents precipitation - rain and snow - from entering the ventilation ducts, which is especially important for operation in regions with a difficult climate. The protective elements of the casing ensure reliable tightness and durability even during long term operation.
The materials from which deflectors are manufactured include galvanised steel, aluminium and stainless steel. The choice depends on the operating conditions and corrosion resistance requirements. Due to its self-contained nature and no energy consumption, the deflector is an environmentally friendly and cost-effective solution.
The operation of the deflector is directly dependent on the weather conditions. In calm conditions it functions as a protective umbrella, but in moderate winds (from 2 m/s) it creates a noticeable increase in draught. The optimum efficiency of most models is achieved at wind speeds of 5-10 m/s. Modern designs tend to reduce the dependence on wind direction through symmetrical forms and rotating constructions.
Special attention is paid to controlled turbulence in modern models. Turbulisers integrated in the housing help to create mixing flow zones, enhancing ejection and stabilising the system even in difficult aerodynamic conditions, e.g. on the roofs of high-rise buildings or in tight city areas.
Thus, a modern ventilation deflector is a highly efficient device that combines the principles of aerodynamics, energy efficiency and reliability. It ensures a stable draught, protects ventilation ducts from external influences and contributes to the creation of a favourable indoor climate without additional energy costs.
