**2.1 Swirl angle measurement**

The main objective of the study is to evaluate the swirling motion in the intake pipe and associated with submerged vortex without and with the installation of floor splitter plate. Initially, the experiment was conducted without the installation of floor splitter plate to capture the initial conditions of the setup. The measurement of the intensity of swirl in the intake pipe was performed according to the procedure described in ANSI/HI 9.8-2018 standard for pump sump model test. The parameter used to quantify the measurement data is the swirl angle *θ* which is defined in the following equation: <sup>θ</sup> = *tan*−1(\_

$$
\Theta = \tan^{-1} \left( \frac{\pi d n}{\nu} \right) \tag{1}
$$

**149**

**Figure 3.**

*Swirl metre installation according to ANSI/HI 9.8-2018 standard.*

**Figure 2.**

*Main dimensions of the sump model and splitter.*

*Application of Vortex Control Principle at Pump Intake DOI: http://dx.doi.org/10.5772/intechopen.92853*

blades used to capture the swirling motion in the intake pipe, and the revolution count of the swirl metre blade is measured using a tachometer. **Figure 3** shows typical swirl metre installation according to ANSI/HI 9.8-2018 standard. Basically, *θ* is the convention for describing the ratio between the axial velocity and the tangential velocity of the intake flow which characterizes the intensity of the swirling motion in the fluid. The acceptance criteria according to ANSI/HI 9.8-2018 is that the swirl

In order to generate the submerged vortex, the clearance under the pipe was set to 0.3 times the diameter of the inlet *D* and two types of flow conditioners

angle must be lower than 5° to prevent excessive swirl in the intake flow.

where *d* is the inner diameter of the intake pipe, *n* is the revolution count of the measurement instrument called the swirl metre and a is the average axial velocity at the location of the swirl metre. The swirl metre consists of a shaft with four straight

**Figure 1.** *The experimental rig.*

#### *Application of Vortex Control Principle at Pump Intake DOI: http://dx.doi.org/10.5772/intechopen.92853*

*Vortex Dynamics Theories and Applications*

**2. Methodology**

**2.1 Swirl angle measurement**

defined in the following equation:

<sup>θ</sup> = *tan*−1(\_

AVD is outlined in ANSI/HI 9.8-2018 [5] standard which is a guideline to assist engineers and designers in optimal intake sump design. Among the AVD types employed in real applications are floor splitter [6], floor cone [7] and corner fillet [8]. These AVD types serve the purpose of eliminating submerged vortices formed at the sump floor. Floor splitters are the most widely used AVD type due to its effectiveness in eliminating vortices and reducing vorticity in the pump intake flow. There are two versions of floor splitter, namely the prism and the plate types. The use of plate type floor splitter is favourable in many applications due to its fabrication friendly-feature and economic design [9]. However, there are a limited number of articles in the literature which discuss the features of floor splitter plate in detail. In this chapter, the characteristics of swirl angle reduction of a floor splitter plate installed in pump sump are studied.

The study was carried out by both experimental and numerical approaches. A single intake pump sump model, as shown in **Figure 1**, was utilized for the study in which the sample of a floor splitter was installed beneath an intake suction pipe in the sump model. The layout of the sump model test section and the dimensions of the floor splitter installed is illustrated in **Figure 2(a)** and **(b)**, respectively.

The main objective of the study is to evaluate the swirling motion in the intake pipe and associated with submerged vortex without and with the installation of floor splitter plate. Initially, the experiment was conducted without the installation of floor splitter plate to capture the initial conditions of the setup. The measurement of the intensity of swirl in the intake pipe was performed according to the procedure described in ANSI/HI 9.8-2018 standard for pump sump model test. The parameter used to quantify the measurement data is the swirl angle *θ* which is

*dn*

where *d* is the inner diameter of the intake pipe, *n* is the revolution count of the measurement instrument called the swirl metre and a is the average axial velocity at the location of the swirl metre. The swirl metre consists of a shaft with four straight

*<sup>v</sup>* ) (1)

**148**

**Figure 1.**

*The experimental rig.*

**Figure 2.** *Main dimensions of the sump model and splitter.*

blades used to capture the swirling motion in the intake pipe, and the revolution count of the swirl metre blade is measured using a tachometer. **Figure 3** shows typical swirl metre installation according to ANSI/HI 9.8-2018 standard. Basically, *θ* is the convention for describing the ratio between the axial velocity and the tangential velocity of the intake flow which characterizes the intensity of the swirling motion in the fluid. The acceptance criteria according to ANSI/HI 9.8-2018 is that the swirl angle must be lower than 5° to prevent excessive swirl in the intake flow.

In order to generate the submerged vortex, the clearance under the pipe was set to 0.3 times the diameter of the inlet *D* and two types of flow conditioners

**Figure 3.** *Swirl metre installation according to ANSI/HI 9.8-2018 standard.*

were installed: a sloped floor with an inclination angle of 30° and a sloped wall with the same inclination angle. These flow conditioners were installed at a distance of about 5D from the centre of the intake pipe as shown in **Figure 4(a)** and **(b)**, respectively. The measurement was conducted in a range of pump submergence levels which are normalized by the minimum inlet submergence *Smin*, a threshold value before the occurrence of a surface vortex. *Smin* is calculated by the following equation:

$$S\_{\rm min} = D \left( \mathbf{1} + \mathbf{2}.3 Fr\_{\rm in} \right) \tag{2}$$

*Frin* is the Froude number at the pipe inlet and is given by:

$$\text{upe inner andu is given by:}$$

$$Fr\_{in} = \frac{\nu\_{in}}{\sqrt{\text{g}D}}\tag{3}$$

where *νin* is the flow velocity at the inlet and *g* is the gravitational acceleration. The range of the dimensionless parameter *S/Smin* was set between 0.8 and 1.2.

**Figure 4.** *False floor and false wall arrangements.*

#### **Figure 5.**

*Numerical model of the full-scale pump sump; (a) the computational domain, (b) model without floor splitter plate, (c) model with floor splitter plate.*

**151**

**Figure 6.**

**Table 1.**

*Dimensions of the full-scale model.*

dimensions are listed in **Table 1**.

*Application of Vortex Control Principle at Pump Intake DOI: http://dx.doi.org/10.5772/intechopen.92853*

**2.2 Numerical simulation of flow in full-scale pump sump**

*Dimension values of the full-scale model shown in Figure 6.*

The numerical approach part of the study is set for the simulation of the flow in a full-scale pump sump. As the construction cost for a full-scale pump sump cannot be afforded, a computational fluid dynamics (CFD) simulation was employed as a replacement. The numerical model was validated with experimental data and incorporated with a combined flow conditioner that consists of inclined floor and inclined wall as the ones used in the experiment and built at a scale of 9:1. The flow rate of the pump was set to 2170 l/s, and the pump submergence took the value of *Smin* which is, after the calculation by using Eq. (2), equals to 2678 mm. The mesh structure and the dimensions of the full-scale pump sump are illustrated in **Figures 5** and **6**, respectively, while the values of the model

**Parameter Dimension (mm)** Inlet diameter *D* 1275 Pipe diameter *d* 850 Right side distance *W*1 1190 Left side distance *W*2 1360 Water entrance width *W*3 1275 Intake pipe height *H*1 9350 Sump height *H*2 4250 Water entrance height *H*3 2975 Floor length *L*1 6375 Water entrance distance from sloped floor *L*2 8417 Clearance *C* 382.5

*Application of Vortex Control Principle at Pump Intake DOI: http://dx.doi.org/10.5772/intechopen.92853*

#### **Figure 6.**

*Vortex Dynamics Theories and Applications*

by the following equation:

were installed: a sloped floor with an inclination angle of 30° and a sloped wall with the same inclination angle. These flow conditioners were installed at a distance of about 5D from the centre of the intake pipe as shown in **Figure 4(a)** and **(b)**, respectively. The measurement was conducted in a range of pump submergence levels which are normalized by the minimum inlet submergence *Smin*, a threshold value before the occurrence of a surface vortex. *Smin* is calculated

> *Frin* = \_ *vin* √ \_

where *νin* is the flow velocity at the inlet and *g* is the gravitational acceleration.

The range of the dimensionless parameter *S/Smin* was set between 0.8 and 1.2.

*Frin* is the Froude number at the pipe inlet and is given by:

*Smin* = *D*(1 + 2.3 *Frin*) (2)

*gD* (3)

**150**

**Figure 5.**

**Figure 4.**

*plate, (c) model with floor splitter plate.*

*False floor and false wall arrangements.*

*Numerical model of the full-scale pump sump; (a) the computational domain, (b) model without floor splitter* 

*Dimensions of the full-scale model.*


#### **Table 1.**

*Dimension values of the full-scale model shown in Figure 6.*

#### **2.2 Numerical simulation of flow in full-scale pump sump**

The numerical approach part of the study is set for the simulation of the flow in a full-scale pump sump. As the construction cost for a full-scale pump sump cannot be afforded, a computational fluid dynamics (CFD) simulation was employed as a replacement. The numerical model was validated with experimental data and incorporated with a combined flow conditioner that consists of inclined floor and inclined wall as the ones used in the experiment and built at a scale of 9:1. The flow rate of the pump was set to 2170 l/s, and the pump submergence took the value of *Smin* which is, after the calculation by using Eq. (2), equals to 2678 mm. The mesh structure and the dimensions of the full-scale pump sump are illustrated in **Figures 5** and **6**, respectively, while the values of the model dimensions are listed in **Table 1**.
