Analytical Study of Performance of a Centrifugal Pump for Different Operating Conditions

Transcription

1 Analytical Study of Perforance of a Centrifugal Pup for Different Operating Conditions Dadapeer D 1, Veeresh G Gunjalli 2 Assistant Professor, Mechanical Engineering Departent, A.G.M.R College of Engineering and Technology, Varur, Karnataka India 1, Assistant Professor, Mechanical Engineering Departent, K.L.E.I.T, Hubli, Karnataka, India 2, Abstract: - Centrifugal pups are used extensively for hydraulic transportation of liquids over short to ediu distance through pipelines where the requireents of head and discharge are oderate. Fro such literature, it was found that ost previous research, especially research based on analytical and nuerical approaches had focused on the design or near-design state of pups. Few efforts were ade to study the off-design perforance of pups. Therefore, Perforance evaluation of turbo achine is essential in order to deterine the safe operating zone. Keywords: - hydraulic transportation, pipelines. I. Introduction: - The centrifugal pup is the ost used pup type in the world. The principle is siple, well-described and thoroughly tested, and the pup is robust, effective and relatively inexpensive to produce. There is a wide range of variations based on the principle of the centrifugal pup and consisting of the sae basic hydraulic parts. Principle of the centrifugal pup an increase in the fluid pressure fro the pup inlet to its outlet is created when the pup is in operation. This pressure difference drives the fluid through the syste or plant. It does so by converting energy of a prie over (an electric otor or turbine) first into velocity or kinetic energy, and then into pressure energy of a liquid that is being puped. II. Description of the proble: - This work is to evaluate the head flow characteristics of a centrifugal pup. Further the perforance of the pup at different rotating speed (design and off design speed) and different ass flow rate i.e. 130 kg/s to 220 kg/s is studied through characteristics curves. The analytical study gives the clear inforation about stalling of the pup and perforance of the pup at different conditions. Outlet blade angle = β 2 = 30 Total pressure of Pascal s Design Mass flow rate: 155 Kg/s Design Blade rotating speed: 1500 rp (Anticlockwise direction) Working fluid = Water at STP condition Nuber of blades = 5 Design Delivery head = 130 IV. Ideal Velocity Triangles of a Centrifugal Pup V. For the designed centrifugal pup analytical calculations were done by considering the ideal velocity triangle of centrifugal pup. Fig.1.1 shows the velocity triangles at the inlet and outlet tips of a vane fixed to the ipeller. The inlet fluid velocity and inlet blade angle were drawn with respect to the ipeller and along with this outlet fluid velocity and outlet blade angle also drawn. With these velocity triangles one can able to predict the perforance characteristics of centrifugal pup. VI. Assuptions Radial and tangential direction. The ipeller passages are copletely filled with the flowing fluid at all tie (no void spaces) The strealines have a shape siilar to the blade s shape Incopressible, inviscid, and single phase fluid The velocity profile is syetric III. Specifications of the Designed Pup Outlet diaeter of ipeller = D 2 = 50 c = 0.5 Width of the ipeller = B 2 = 5 c = 0.05 Fig.1.1 Velocity triangles at Inlet and outlet of a centrifugal pup ISSN: Page 175

2 ipeller D 1 & D 2 =Diaeter of the ipeller at inlet & outlet () N = Speed (rp) U 1 = πd 1 N/60, Tangential velocity of the ipeller at inlet (/s) U 2 = πd 2 N/60, Tangential velocity of the ipeller at outlet (/s) V 1 =absolute velocity of the liquid at inlet (/s) V 2 = absolute velocity of the liquid at outlet (/s) V f1 & V f2 are the velocities of flow at inlet and outlet (/s) V r1 & V r2 Relative velocities at inlet and outlet (/s) V u2 whirl velocity at outlet (/s) β 1 = blade angle at inlet β 2 = blade angle at outlet H = Head () Saple trial calculation for a design condition at constant speed N = 1500 rp, ass flow rate = 155 kg/s (Ref. table 1.2) Manoetric efficiency is assued based on the ass flow rate, Assuing the anoetric efficiency = 95% Discharge, ( 3 /s) Q = / 3 /s Tangential velocity of the ipeller at outlet (/s) U2 = D 2 N/60 = /s Flow velocity at outlet (/s) Q = = D 2 *B 2 *V f2 V f2 = Q/ D 2 *B 2 = 0.155/ 0.5*0.05 = /s tan β 2 = tan 30 = 0.57 X = V f2 / tan β 2 = / 0.57 = /s Whirl velocity at outlet (/s) V u2 = U 2 X = = /s Head () V u2 * U 2 / g = *39.275/9.81 = The above calculations were done for design conditions i.e for ass flow rate of 155 kg/s and speed of 1500 rp fro which the theoretical head is getting as Siilar calculations were done for different discharges (130 kg/s to 200 kg/s), different speeds (1000 rp to 2000 rp) and the results are tabulated as shown in the table 1.1 to table 1.7. Table 1.1 perforance paraeters for varying ass flow rates (130 to 200 kg/s) at constant speed 1000 rp Q N U 2 V f2 tan X V u2 H kg/s 3 /s rp /s /s β 2 /s /s Graph 1.1 Head () V/S Mass flow rate (kg/s) at constant speed 1000 rp Graph 1.1 shows that as ass flow rate increases for a fixed speed i.e 1000 rp, head is going to decrease and at soe point there is sudden drop in the head i.e at 200 kg/s Table 1.2 perforance paraeters for varying ass flow rates (130 to 200 kg/s) at constant speed 1500 rp Q N U 2 V f2 tan X V u2 H kg/s 3 /s rp /s /s β 2 /s /s ISSN: Page 176

3 Graph 1.2 Head () V/S Mass flow rate (kg/s) at constant speed 1500 rp Graph 1.2 shows that as ass flow rate increases for a fixed speed i.e 1500 rp, head is going to decrease and at soe point there is sudden drop in the head i.e at 200 kg/s, this indicates the separation of flow fro the ipeller blade. Table 1.3 perforance paraeters for varying ass flow rates (130 to 200 kg/s) at constant speed 2000 rp Q N U 2 V f2 tan X V u2 H kg/s 3 /s rp /s /s β 2 /s /s Graph 1.3 Head () V/S Mass flow rate (kg/s) at constant speed 2000 rp Graph 1.3 shows that as ass flow rate increases for a fixed speed i.e 2000 rp, head is going to decrease and at soe point there is sudden drop in the head i.e at 200 kg/s, this indicates the separation of flow fro the ipeller blade. Table 1.4 perforance paraeters for varying speed (1000 to 2000 rp) at constant ass flow rate 130 kg/s N rp kg/s Q 3 /s U 2 /s V f2 /s tan β 2 X /s V u2 /s Graph 1.4 Head () V/S Speed (rp) at constant ass flow rate 130 kg/s Graph 1.4 shows that as speed increases for a fixed Table 1.5 perforance paraeters for varying speed (1000 to 2000 rp) at constant ass flow rate 155 kg/s N Q U 2 rp kg/s 3 /s V /s f2 /s tan X /s V u2 H β 2 /s H ISSN: Page 177

4 Graph 1.5 Head () V/S Speed (rp) at constant ass flow rate 155 kg/s Graph 1.4 shows that as speed increases for a fixed Table 1.6 perforance paraeters for varying speed (1000 to 2000 rp) at constant ass flow rate 180 kg/s N Q U 2 rp kg/s 3 /s /s V f2 /s tan β 2 X /s V u2 /s H Table 1.7 perforance paraeters for varying speed (1000 to 2000 rp) at constant ass flow rate 200 kg/s N Q U 2 rp kg/s 3 /s V /s f2 /s tan X /s V u2 H β 2 /s Graph 1.7 Head () V/S Speed (rp) at constant ass flow rate 200 kg/s Graph 1.7 shows that as speed increases for a fixed Graph 1.6 Head () V/S Speed (rp) at constant ass flow rate 180 kg/s Graph 1.6 shows that as speed increases for a fixed Conclusion Table 1.1 to 1.3 shows the results of centrifugal pup carried by analytical ethod and it can be observed that as the ass flow rate increases for fixed speed, head also increases. For graph 1.1 to 1.3 it can be observed that as ass flow rate increases the head also increases, but at soe point there is sudden drop in the head that indicates, there is a flow separation takes place i.e at 200 kg/s so the stalling effect is going to occur at this point. Table 1.4 to 1.7 shows the results of centrifugal pup at constant ass flow rate and the speed will be varied, fro the graph 1.4 to 1.7 it can be observed that as the speed increases blade torque also increases therefore the input power required to run the pup also increases. ISSN: Page 178

5 Reference [1] Abdulkadir Aan, Sileshi Kore and Edessa Dribssa* flow siulation and perforance prediction of centrifugal pups using cfd-tool [2] K M Guleren and A Pinarbasi* Nuerical siulation of the stalled flow within a vaned centrifugal pup [3] R.RAGOTH SINGH1,2 & M.NATARAJ3 paraetric study and optiization of centrifugal pup ipeller by varying the design paraeter using coputational fluid dynaics: part i [4] E.C. Bacharoudis*,1, A.E. Filios2, M.D. Mentzos1 and D.P. Margaris1 Paraetric Study of a Centrifugal Pup Ipeller by Varying the Outlet Blade Angle [5] LIU Houlin*, WANG Yong, YUAN Shouqi, TAN Minggao, and WANG Kai Effects of Blade Nuber on Characteristics of Centrifugal Pups [6] SHI Weidong, ZHOU Ling*, LU Weigang, PEI Bing, andla NG Tao Nuerical Predictionand Perforance Experient i n a Deep well Centrifual Pup with Different IpelOutlet W idth [7] K.M. Pandey*, A.P. Singh1 and Sujoy Chakraborty2 Nuerical studies on effects of blade nuber variations on perforance of centrifugal pups at 2500 rp. [8] Thord Wennberg1, Anders Sellgren2, Lee Whitlock3 Predicting the perforance of centrifugal pups when handling coplex slurries [9] Khin Cho Thin, Mya Mya Khaing, and Khin Maung Aye Design and Perforance Analysis of Centrifugal Pup ISSN: Page 179