**2. Experimental apparatus**

In this study, PIV was used to study the hydrodynamic structure generated with the convex blade turbine in a stirred vessel. For the particle image velocimetry, the flow is illuminated by an Nd-YAG 532 nm green pulsed laser source generated in 2 30 mJ. The acquisition of the two-dimensional image data was taken with a CCD camera with 1600 1200 pixels of resolutions. The results are obtained for 170 images at three different azimuthally planes. The average diameter of the seeding particle was equal to dp = 20 μm with 0.15 g of concentration. The cylindrical vessel was mounted in a squared vessel to decrease reflection which is filled by water. The height of the water is equal to the tank diameter (D = 300 mm). Besides, the turbine diameter is equal to the half of the vessel diameter (T = D/2), and it is placed in the middle of the tank. Four equally spaced baffles which are placed 90° far from one another were used. The rotation speed of the turbine is equal to N = 70 rpm which is equal to a Reynolds of Re = 26,250. The velocity at the tip of the impeller is equal to Utip = 0.55 m/s. The velocity speed is settled by using an electrical motor placed at the top of the tank and controlled automatically by the computer. In addition, the azimuthally plane of the investigation is localized at θ = 10° from the blade. The angular position between two successive blades is settled through a position sensor localized near the electrical motor.

**3. Data analysis**

**Figure 2.** *Staged system.*

**165**

**Figure 1.** *One-staged system.*

velocity ui and a temporal fluctuating term u<sup>0</sup>

which the velocity was measured for each acquisition. The mean velocity is calculated as follows:

ui,rms <sup>¼</sup> <sup>u</sup>0<sup>2</sup>

ij � �<sup>1</sup>*=*<sup>2</sup>

For a given point, the instantaneous velocity components uij in terms of a mean

*The Effects of Curved Blade Turbine on the Hydrodynamic Structure of a Stirred Tank*

*DOI: http://dx.doi.org/10.5772/intechopen.92394*

uij ¼ ui þ u<sup>0</sup>

where i refers to the velocity component r, z, or θ and j refers to the instant at

j¼1

ui <sup>¼</sup> <sup>1</sup> Nn X Nn

With Nn refers to the snapshot total number. The average of the temporal fluctuating terms which known as a root mean square (rms) value is given by

> <sup>¼</sup> <sup>1</sup> Nn X Nn

0 @

j¼1

uij‐ui � �<sup>2</sup>

1 A

1*=*2

(3)

ij is given as

ij (1)

uij (2)

**Figure 1** shows the different impellers geometry for the one-staged system namely, flat, concave, and convex blade impeller. **Figure 2** shows the staged system. In fact, the highest impeller is localized at the third position according to the free surface, and the lowest one is localized at the third position according to the bottom. For the first configuration (**Figure 2(a)**), the flat blade impeller is localized at the highest position and the concave blade impeller at the bottom (PD8 h, PI8 concave). For the second configuration, the impeller at the bottom is replaced by the convex impeller (PD8 h, PI8 convex). For the third and the fourth configurations, the flat blade impeller is localized at the bottom, and the highest impeller is occupied by the concave and the convex blade impeller, respectively (PD8 b, PI8 concave; PD8 b, PI8 convex).

*The Effects of Curved Blade Turbine on the Hydrodynamic Structure of a Stirred Tank DOI: http://dx.doi.org/10.5772/intechopen.92394*

and the PIV technique to calculate the velocity field generated by a Rushton turbine. In-line high shear mixers (HSMs) with double rows of ultrafine inclined stator teeth were experimentally and numerically investigated under different rotor speeds and flow rates [9]. Furthermore, computational fluid dynamics (CFD) simulations were used to investigate the effects of impeller configuration on fungal physiology and cephalosporin C production by an industrial strain *Acremonium chrysogenum* in a bioreactor equipped with conventional and novel impeller configuration, respectively [10]. Navier-Stokes equation in conjunction with the RNG (renormalization group) of the k-ε turbulent model was used to study the turbulent flow induced by the six flat blade turbines (FBT6), the Rushton turbine (RT6), and the pitched blades turbine (PBT6) in a stirred tanks [11]. Finite volume method was employed to solve the Navier-Stokes equations governing the transport of momentum to compare four different turbulence models used for numerical simulation of the hydrodynamic structure generated by a Rushton turbine in a cylindrical tank [12]. Multiple impellers were used in a stirred vessel to form the micro/nano drug parti-

According to the biography, it is interesting to study the effect of the blade shape in order to improve the hydrodynamic structure. In this paper, we are interested in studying the hydrodynamic structure in a cylindrical stirred vessel equipped by an

In this study, PIV was used to study the hydrodynamic structure generated with the convex blade turbine in a stirred vessel. For the particle image velocimetry, the flow is illuminated by an Nd-YAG 532 nm green pulsed laser source generated in 2 30 mJ. The acquisition of the two-dimensional image data was taken with a CCD camera with 1600 1200 pixels of resolutions. The results are obtained for 170 images at three different azimuthally planes. The average diameter of the seeding particle was equal to dp = 20 μm with 0.15 g of concentration. The cylindrical vessel was mounted in a squared vessel to decrease reflection which is filled by water. The height of the water is equal to the tank diameter (D = 300 mm). Besides, the turbine diameter is equal to the half of the vessel diameter (T = D/2), and it is placed in the middle of the tank. Four equally spaced baffles which are placed 90° far from one another were used. The rotation speed of the turbine is equal to N = 70 rpm which is equal to a Reynolds of Re = 26,250. The velocity at the tip of the impeller is equal to Utip = 0.55 m/s. The velocity speed is settled by using an electrical motor placed at the top of the tank and controlled automatically by the computer. In addition, the azimuthally plane of the investigation is localized at θ = 10° from the blade. The angular position between two successive blades is

settled through a position sensor localized near the electrical motor.

**Figure 1** shows the different impellers geometry for the one-staged system namely, flat, concave, and convex blade impeller. **Figure 2** shows the staged system. In fact, the highest impeller is localized at the third position according to the free surface, and the lowest one is localized at the third position according to the bottom. For the first configuration (**Figure 2(a)**), the flat blade impeller is localized at the highest position and the concave blade impeller at the bottom (PD8 h, PI8 concave). For the second configuration, the impeller at the bottom is replaced by the convex impeller (PD8 h, PI8 convex). For the third and the fourth configurations, the flat blade impeller is localized at the bottom, and the highest impeller is occupied by the concave and the convex blade impeller, respectively (PD8 b, PI8

cle in the biopharmaceutical classification system [13].

eight-curved blade turbine.

**2. Experimental apparatus**

*Vortex Dynamics Theories and Applications*

concave; PD8 b, PI8 convex).

**164**

**Figure 2.** *Staged system.*
