Livestock and agricultural activities contribute significantly to atmospheric ammonia emission in Europe. The volatilization process depends on many factors, especially wind speed and rainfall. The most important methods to evaluate ammonia volatilization are the wind tunnel and micrometeorological methods. The tunnels are more flexible and simple to use in every situation. Few studies have been carried out to determine, which conditions are established inside the chamber and how they influence the ammonia volatilization and measurement. The aim of this research was to investigate the effects of the wind tunnel configuration and flow inlet velocity, by means of CFD simulations and wind speed measurements, in order to achieve a better aerodynamic performance. The SST k–ω model used for simulations was first validated in order to prove the consistency of the model itself. Several configurations were simulated and compared. In particular, in order to overcome the asymmetric flow conditions that occurred in all wind tunnel configurations, four flow distribution devices were proposed and simulated. The best setup was chosen with the purpose of reaching both the best uniform velocity distribution (to ensure homogeneous volatilization from the emitting surface) and easy transport for field applications. It consists of an emission chamber 40 cm wide, 25 cm high and 80 cm long, situated between a divergent diffuser and a convergent duct, respectively 50 cm and 25 cm long. Moreover, structures similar to honeycombs, namely guiding channels, were introduced in the divergent diffuser, because they showed the best aerodynamic performance. These 20 channels, located in the divergent diffuser, prevent flow from separating, by means of the reduction of the expansion angle, obtaining the desired flow conditions inside the wind tunnel. Finally, it was verified that CFD confirmed its usefulness as a decision-support instrument to design and simulate possible solutions, reducing design time.
Study of aerodynamic performances of different wind tunnel configurations and air inlet velocities, using computational fluid dynamics (CFD) / SCOTTO DI PERTA, Ester; Agizza, Maria Angela; Sorrentino, Giancarlo; Boccia, Lorenzo; Pindozzi, Stefania. - In: COMPUTERS AND ELECTRONICS IN AGRICULTURE. - ISSN 0168-1699. - 125:(2016), pp. 137-148. [10.1016/j.compag.2016.05.007]
Study of aerodynamic performances of different wind tunnel configurations and air inlet velocities, using computational fluid dynamics (CFD)
SCOTTO DI PERTA, ESTER;SORRENTINO, GIANCARLO;BOCCIA, LORENZO;PINDOZZI, STEFANIA
2016
Abstract
Livestock and agricultural activities contribute significantly to atmospheric ammonia emission in Europe. The volatilization process depends on many factors, especially wind speed and rainfall. The most important methods to evaluate ammonia volatilization are the wind tunnel and micrometeorological methods. The tunnels are more flexible and simple to use in every situation. Few studies have been carried out to determine, which conditions are established inside the chamber and how they influence the ammonia volatilization and measurement. The aim of this research was to investigate the effects of the wind tunnel configuration and flow inlet velocity, by means of CFD simulations and wind speed measurements, in order to achieve a better aerodynamic performance. The SST k–ω model used for simulations was first validated in order to prove the consistency of the model itself. Several configurations were simulated and compared. In particular, in order to overcome the asymmetric flow conditions that occurred in all wind tunnel configurations, four flow distribution devices were proposed and simulated. The best setup was chosen with the purpose of reaching both the best uniform velocity distribution (to ensure homogeneous volatilization from the emitting surface) and easy transport for field applications. It consists of an emission chamber 40 cm wide, 25 cm high and 80 cm long, situated between a divergent diffuser and a convergent duct, respectively 50 cm and 25 cm long. Moreover, structures similar to honeycombs, namely guiding channels, were introduced in the divergent diffuser, because they showed the best aerodynamic performance. These 20 channels, located in the divergent diffuser, prevent flow from separating, by means of the reduction of the expansion angle, obtaining the desired flow conditions inside the wind tunnel. Finally, it was verified that CFD confirmed its usefulness as a decision-support instrument to design and simulate possible solutions, reducing design time.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
