Numerical Modeling Of Flow Pattern In Kamal Saleh Dam Spillway Approach Channel

Transcription

1 Applied Science Reports E-ISSN: / P-ISSN: DOI: /PSCP.ASR App. Sci. Report. 10 (2), 2014: PSCI Publications Numerical Modeling O Flow Pattern In Kamal Saleh Dam Spillway Approach Channel Amir Moradinejad 1, Abas Parssai 2, Mohamad Noriemamzade 3 1. PHD student Water Engineering Department, Faculty o Agriculture,Lorestan University, Khorramabad, Lorestan Province,Iran And Master o Institute o Applied Science Department o Agriculture and jehad Ministry 2. PHD student Water Engineering Department, Faculty o Agriculture,Lorestan University,Khorramabad,Lorestan Province,Iran 3. Associate Proessor, Water Engineering Department,Faculty o Agriculture, Sharekord University, Sharekord, Charmahal Province,Iran. Corresponding author Amir Moradinejad Paper Inormation Received: 10 March, 2015 Accepted: 7 May, 2015 Published: 20 May, 2015 Citation Moradinejad A, Parssai A, Noriemamzade M Numerical Modeling O Flow Pattern In Kamal Saleh Dam Spillway Approach Channel. Applied Science Reports, 10 (2), Retrieved rom (DOI: /PSCP.ASR ) A B S T R A C T Analysis o behavior and hydraulic properties o low over the spillway dam is a complicated phenomenon that takes lots o money and time. To modeling o Hydraulic characteristics several ways as physical modeling and numerical methods has proposed. Today, using the sotware o Computational Fluid Dynamics (CFD) and modern computers, have developed the usage o numerical methods in the analysis o low. The sotware related to CFD is Flow 3D that has the capability to analyze two and three dimensional low ield. In this paper the low pattern at guide wall o the Kamal-Saleh has been modeled by Flow 3D sotware. The result shows that the current shape o the let guide wall cased to unsteady low and making the secondary low at beginning the weir. This shape o guide wall maybe reduced the perormance o weir to remove the pick lood discharge PSCI Publisher All rights reserved. Key words: Approach channel, Kamal-Saleh dam, Guide wall, Spillway, numerical modeling. Introduction Spillways are one o the main structures that used in the Dam projects. Design o spillway in all type o dams, Speciically Earthen dams is more important because inability to remove Probable Maximum Flood (PMF) discharge by spillway may cause to overlow o water on the earthen dam which ultimately leads to destruction the dam(das & DAS SAIKIA, 2009; E, 2013; Novak et al., 2007). So study on the hydraulic characteristics o this structure is important. Hydraulic properties o spillway including low pattern at the entrance o the guide walls and along the chute, Moreover, estimating the values o velocity and pressure parameters o low during along the chute is very important(chanson, 2004; Chatila & Tabbara, 2004). The purpose o the study on the low pattern is the eect o wall geometry to creation the transverse waves, Flow instability, rotating and reciprocating low through the inlet o spillway and its chute(wang & Jiang, 2010). The purpose o study on the values o velocity and pressure are calculating the potential o the structure to occurrence the phenomena such as cavitation (Fattor & Bacchiega, 2009; Ma et al., 2010). Sometimes, it can be seen that the spillway design parameters o pressure and velocity is very suitable But geometry is considered is not suitable or conducting walls Causing unstable low pattern over the spillway, Rotating lows at the beginning the spillway and Its designed cased to reduce the lood discharge capacity(fattor & Bacchiega, 2009). Study on spillway, usually done with making physical models (Su et al., 2009; Suprapto, 2013; Wang & Chen, 2009; Wang & Jiang, 2010). But recently, with advancing in the ield o CFD, study on Hydraulic characteristics o this structure has been done with these techniques (Chatila & Tabbara, 2004; Zhenwei et al., 2012). Using the CFD as a powerul technique or modeling the Hydraulic structures can reduce the time and cost o experiments(tabbara et al., 2005). In CFD ield, the Navier-Stokes equation has solved by powerul numerical methods such as inite element method and inite volumes (Kim & Park, 2005; Zhenwei et al., 2012). In order to obtain closed orm Navier-Stokes equations turbulence

2 models, such k and RNG is presented. To use the technique o computational luid dynamics sotware packages such as Fluent and Flow 3D, etc. are provided, Recently, These two sotware packages widely used in hydraulic engineering because the perormance and these accuracy are very suitable(gessler; Kim, 2007; Kim et al., 2012; Milési & Causse, 2014; Montagna et al., 2011). In this paper, to assessing the low patter at Kamal-Saleh guide wall the numerical method has been used. All the stage o numerical modeling was conducted in the Flow 3D sotware. Kamal -Saleh Dam basin has an area o 655 square kilometers. Is located in South West Markazi Province a west o Iran. Figure 1 shows the picture o this structure. Figure 1. Kamal Saleh guide walls and Spillway Materials and Methods Firstly a three dimensional model has constructed according to two dimensional map that prepared or designing o spillway Then a small model was prepared with scale o 1:80 and entered the Flow 3D sotware, all stage o model construction was conducted in AutoCAD 3D. Flow 3D sotware solved numerically The Navier-Stokes equation in both compressible and incompressible modes by inite volume method. Below is a brie reerences on the equations that used in the sotware. Review o the governing equations in sotware Flow3D Continuity equation at three dimensional Cartesian coordinates given as Eq(1). PSOR v uax va y wa z t x x x (1) Where u, v, z are Velocity component in the x, y, z direction. A, A, A Cross Sectional area o the low, Fluid density, PSOR the source term, the Eq (2). x y z v is the volume raction o the luid and Three-dimensional momentum equations given in u 1 u u u 1 P ua va wa G t v x y z x x y z x x v 1 v v v 1 P ua va wa G t v x y z y x y z y y w 1 w w w 1 P ua va wa G t v x y z y x y z z z Where, P is the luid pressure, Gx, G y, G z The Acceleration created by body luids, three dimensions and v x, y, z (2) Viscosity acceleration in is related to the volume o luid, deined that by the equation (3). For modeling o ree surace 83

3 proile the VOF Technique based on the volume raction o the computational cells has been used. Since the volume raction F represents the amount o luid in each cell, takes Value between 0 and 1. F 1 FA xu FA yv FA zw 0 t v x y y Turbulence models Flow 3D oers 5 types o Turbulence models: Prantl mixing length, K-ε equation, RNG models, Large eddy simulation model. the simplest model would be a transorm equation or the kinetic energy along with luctuation o turbulence velocity and another parameter which deines some other characteristics o turbulence. Turbulence models have been proposed recently is based on Reynolds-averaged Navier Stokes equations. These approaches involves statistical methods to extract an averaged equation related to the turbulence quantities. Steps o solving a problem in Flow3D sotware Preparing the 3D model by AutoCAD sotware. 2. Deining the problem in the sotware and check the inal mesh.3.choosing the basic equations that should be solved. 4. Deining the characteristics o luid. 5. Deining the boundary conditions. 6. Initialization o the low ield. 7. Adjusting the output. 8. Adjusting the control parameters, choice o the calculation method and solution ormula. 9.start o calculation. Deining o Boundary Conditions(BC) are important stage o simulation with Flow 3D sotware. This sotware has a wide range o boundary conditions. (3) Figure 2. Three-dimensional shape o the, Kamal Saleh spillway Figure 3. meshing the geometry and boundary conditions o the model Flow 3D Results and discussion The behavior o water in spillway is strongly aected by the low pattern at the entrance o the spillway, the low pattern ormation at the entrance is aected by the guide wall, and choice o an optimized orm or the guide wall has a great eect on rising the ability o spillway to easily the PMF, so any turbulence in approach channel can cause turbulence in the spillway, low reduction, and even probability o cavitation. Optimize the low guiding walls (in terms o length, angle and radius) can cause the loss o turbulence and low disturbances on spillway. For this purpose, initially proposed or model or the discharge o spillway dam, Kamal Saleh, 80, 100, 120 liters per second were surveyed. The reorm proposals are presented. Geometric properties o the conducting Guidance wall are given in the ollowing table. 84

4 Table 1. Characteristics and dimensions o the guidance walls tested Case Direct Length(m) Radius o curvature(m) Cobb angles(degree) The pattern o low in the guidance wall According to (4), (5) and (6) and the observed streamline the right wall is suitable perormance but the let wall was not suitable perormance and the let wall o the geometric design creates a secondary low in the irst part o the wall guidance direct input to spillway. The causes o transverse waves at beginning o spillway. By increasing the low rate at the inlet spillway Rotational lows gone But the lines can cause severe distortion. The results o the sotware implementation to increase the low in the igures (7) to (9) and (11) to (14) are given. As the orms (8) and (9) is observed The right wall is good But the let wall is not suitable And perversion low lines are clearly marked. Transverse waves produced severe curvature o the low lines in Figure (14) and (10) are given. Ater checking the suitability o the proposed project and the right wall, It has been suggested that the geometry o the let wall, right wall should be like. Three-dimensional model was built by AutoCAD sotware spillway again Flow 3D sotware was inside, The sotware was Ron or spillway modiied. The results o the sotware implementation or maximum low and Modiied wall The igures (18) and (19) are shown. Modiying eect on the geometry o the let wall o the spillway inlow patterns were studied. According to the igures (18) and (19) Correction the let wall Cause the current guidance And Elimination o a severe curvature o the low lines. Eventually Makes it easy to cross the stream and Transverse waves are eliminated. This geometry increases the eiciency o the spillway when design lood will occur. Conclusions and recommendations the right wall is good But the let wall was not good and This geometric design creates a Rotating low At the beginning o spillway and The transverse waves are caused. increasing the low rate at the inlet weir on the let wall o waves and Rotational lows gone, But the lines can cause severe distortion. Modiy the let wall, causing the current guidance and Severe curvature o the low lines is eliminated and Eventually lead to easy passage and eliminates the cross waves is. large radius and angle o the curve, causing widening o the canal wall approach (Approach-Channel) and to reduce the inluence o the wall is conducted. Figure 4. in the model proposed or the low o 80 liters per second 85

5 Figure 5. low pattern down the right wall Figure6. the pattern o low through the side wall o the let Figure 7. proposed to model the low rate o 100 liters per second Figure 8. low pattern down the right wall 86

6 Figure 9. pattern o low through the side wall o the let Figure 10. two-dimensional low pattern on the spillway crest Figure 11. presents the low pattern in the design low o 120 liters per second Figure 12. shows the low pattern near the wall in right direction 87

7 Figure 13. to guide the low pattern near the let wall. Figure 14. two-dimensional low pattern on the wall o the spillway crest guidance Figure 15. proposed a model or the low rate o 120 liters per second Figure 16. (16) to guide the low pattern near the wall. Figure 17. two-dimensional low pattern on the wall o the spillway crest 88

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