A numerical and experimental investigation on the coefficients of discharge and the spray cone angle of a solid cone swirl nozzle

Numerical and experimental investigations have been made on the coefficient of discharge C d and the spray cone angle ψ of a swirl spray solid cone pressure nozzle. The theoretical predictions are made from a numerical computation of flow in the nozzle using the standard k– ε model of turbulence. The values of C d and ψ have been evaluated from the radial distributions of velocity components of liquid flow at the nozzle exit. The experiments have been carried out to measure the values of C d and ψ of a solid cone spray nozzle at different operating conditions to validate the numerical predictions. It has been established, from a fair agreement between the theoretical and experimental results, that the adaptation of the standard k– ε model for turbulence in nozzle flow serves well the purpose of predictions of C d and ψ within the range of operating parameters studied in the present work. It has been observed that the coefficient of discharge and the spray cone angle remain almost constant with the Reynolds number Re of the flow at inlet to the nozzle. The coefficient of discharge C d is almost uninfluenced by inlet swirl number S in its lower range, but decreases with S in its higher range. The spray cone angle ψ, on the other hand, always increases with an increase in S. For a given Re, an increase in flow ratio q r (the ratio of flow rate through inlet central port to the total flow through the nozzle) increases the value of C d and decreases the value of ψ. However, the influence of q r on C d is prominent at lower values of D 2/ D 1 (the ratio of the diameters of inlet axial port to the swirl chamber of the nozzle). An increase in the value of C d takes place with a decrease in D 2/ D 1 mainly in the range of higher q r and for values of D 2/ D 1 less than 0.17. The spray cone angle ψ, on the other hand, is almost uninfluenced with D 2/ D 1, except in the situation when ψ increases with an increase in D 2/ D 1, from 0.38 to 0.75 mainly in the lower range of flow ratio q r .