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Blade thickness measurements at the site of Uri Power Station(UPS). Table 11

Table 11 Blade thickness measurements at the site of Uri Power Station(UPS). Table 11

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Constants a and b for various levels of quartz. Table 1
Constants a and b for various levels of quartz. Table 1
Table 2 3. Proposed erosion model Francis runner the value of n is taken as 3. The function f(a) involves impingement angle a. The function f(a) is obtained from geomet- rical parameters for pipe bends and for the steel grades, it is calculated as per methodology of Varitas [53] which is used in the present model and is given as under: As has been discussed above, the erosion rate depends upon properties of sediment, base material of runner, velocity of fluid or sediment particle and also on the geometrical function(geometry of the surface impinged by the sediment particles). The impinging velocity was taken as particle velocity by some researchers {21,38,51], while others have taken it as the relative velocity of water [15,50]. The characteristic velocity used in IEC-2009 [39], IEC-2013 [40] shows some variation for the different turbine data with the similar design specification. The relative velocity through the runner is dependent upon the turbine size, flow rate, head and the other parameters needed for the design of the runner.
Table 2 3. Proposed erosion model Francis runner the value of n is taken as 3. The function f(a) involves impingement angle a. The function f(a) is obtained from geomet- rical parameters for pipe bends and for the steel grades, it is calculated as per methodology of Varitas [53] which is used in the present model and is given as under: As has been discussed above, the erosion rate depends upon properties of sediment, base material of runner, velocity of fluid or sediment particle and also on the geometrical function(geometry of the surface impinged by the sediment particles). The impinging velocity was taken as particle velocity by some researchers {21,38,51], while others have taken it as the relative velocity of water [15,50]. The characteristic velocity used in IEC-2009 [39], IEC-2013 [40] shows some variation for the different turbine data with the similar design specification. The relative velocity through the runner is dependent upon the turbine size, flow rate, head and the other parameters needed for the design of the runner.
Fig. 1. (a)Typical Francis blade geometry showing impingement angle and radius of curvature (b)velocity triangles at inlet and outlet of blade.
Fig. 1. (a)Typical Francis blade geometry showing impingement angle and radius of curvature (b)velocity triangles at inlet and outlet of blade.
Calculated values of various parameters for Jhimruk Hydroelectric Centre(JHC). Table 4
Calculated values of various parameters for Jhimruk Hydroelectric Centre(JHC). Table 4
The relevant data for Jhimruk Hydroelectric Centre(JHC) [45]. Table 3
The relevant data for Jhimruk Hydroelectric Centre(JHC) [45]. Table 3
Fig. 2. A generic flow diagram representation for calculation of erosion rate of ¢ Francis turbine. Based on the categorization of erosive damage to power stations given by Naidu [57], the Uri Power Station can be put into sub- stantially high damage category as the runner is taken for main- tenance after every four years. Fig. 3 shows the typical areas of massive erosive wear damage of UPS with Fig. 3(a) providing the damage area at runner inlet, Fig. 3(b) providing the damage at runner outlet. Actual measurement of thickness of damaged blades such as given in Fig. 3(c) indicate that the damage is more severe at outlet. It has been found in the present investigation that the
Fig. 2. A generic flow diagram representation for calculation of erosion rate of ¢ Francis turbine. Based on the categorization of erosive damage to power stations given by Naidu [57], the Uri Power Station can be put into sub- stantially high damage category as the runner is taken for main- tenance after every four years. Fig. 3 shows the typical areas of massive erosive wear damage of UPS with Fig. 3(a) providing the damage area at runner inlet, Fig. 3(b) providing the damage at runner outlet. Actual measurement of thickness of damaged blades such as given in Fig. 3(c) indicate that the damage is more severe at outlet. It has been found in the present investigation that the
Fig. 3. (a) Erosive damage (a) at runner inlet, (b) at runner outlet, and (c) measurement of thickness after 2010—2014 time period for UPS. angular types, which is in conformity with petrographic report [58 | of the power station. The angular grains with distinct sharp edges are exemplified by Fig. 7(b) with a magnification of 1600X while multiple sharp edges of a typical silt particle are represented by Fig. 7(c)wherein a magnification of 550X has been used. The shape factor Ks, is obtained by consulting the relevant tables of IEC-2013 [40] wherein the value of K;, has been suggested between 1 and 2 for round to sharp particles. Accordingly a value of 1.5 has been Table 5 Running hours (of the eroded runner) for the four consecutive years of operation with corresponding generation in Million Units(MU). Sediment concentration before desilting basin
Fig. 3. (a) Erosive damage (a) at runner inlet, (b) at runner outlet, and (c) measurement of thickness after 2010—2014 time period for UPS. angular types, which is in conformity with petrographic report [58 | of the power station. The angular grains with distinct sharp edges are exemplified by Fig. 7(b) with a magnification of 1600X while multiple sharp edges of a typical silt particle are represented by Fig. 7(c)wherein a magnification of 550X has been used. The shape factor Ks, is obtained by consulting the relevant tables of IEC-2013 [40] wherein the value of K;, has been suggested between 1 and 2 for round to sharp particles. Accordingly a value of 1.5 has been Table 5 Running hours (of the eroded runner) for the four consecutive years of operation with corresponding generation in Million Units(MU). Sediment concentration before desilting basin
Fig. 4. Sediment concentration before and after desilting basin at Uri Power Station(UPS). chosen for Ks, in the present study as quartz grains and lithic fragments are angular to sub angular in shape, while feldspar grains overall picture of a sample of particles with a magnification factor of 45X and erodents have shapes varying from sub-rounded to
Fig. 4. Sediment concentration before and after desilting basin at Uri Power Station(UPS). chosen for Ks, in the present study as quartz grains and lithic fragments are angular to sub angular in shape, while feldspar grains overall picture of a sample of particles with a magnification factor of 45X and erodents have shapes varying from sub-rounded to
Fig. 6. Microscopic view of mineral composition of silt taken from dam site of UPS. Fig. 5. Particle size distribution for the sediment. appear subrounded. Fig. 6 shows loose grains of fine sand to fine silt, with brownish grey sandy silt having white sheen imparted by the presence of white Mica. Some of the grains of quartz have their veins of ferruginous material. Hornblende grains are pleochroic in shades of light green and are sub-angular to sub-rounded in shape.
Fig. 6. Microscopic view of mineral composition of silt taken from dam site of UPS. Fig. 5. Particle size distribution for the sediment. appear subrounded. Fig. 6 shows loose grains of fine sand to fine silt, with brownish grey sandy silt having white sheen imparted by the presence of white Mica. Some of the grains of quartz have their veins of ferruginous material. Hornblende grains are pleochroic in shades of light green and are sub-angular to sub-rounded in shape.
Then uncertainty in measurement of E is given as follows: An error analysis of parameters of present investigation has been performed on the basis of methodology proposed by Kline and McClintock as cited in Padhy [43] and Moffat [59]. The scatter in raw data used in calculating the result is obtained from a single set of values of necessary input parameters and is applied in the pro- posed model of erosion as,
Then uncertainty in measurement of E is given as follows: An error analysis of parameters of present investigation has been performed on the basis of methodology proposed by Kline and McClintock as cited in Padhy [43] and Moffat [59]. The scatter in raw data used in calculating the result is obtained from a single set of values of necessary input parameters and is applied in the pro- posed model of erosion as,
Particle size distribution of the silt before and after desilting basin. Table 6
Particle size distribution of the silt before and after desilting basin. Table 6
Mineralogical composition and percentage of sediments. Table 7
Mineralogical composition and percentage of sediments. Table 7
Fig. 7. Particle geometry of silt sample taken from dam site of UPS.
Fig. 7. Particle geometry of silt sample taken from dam site of UPS.
Assessment of damage parameters for UPS from IEC-2013 [40] and proposed erosion model. Table 10
Assessment of damage parameters for UPS from IEC-2013 [40] and proposed erosion model. Table 10
The relevant data for Uri Power Station (UPS). Table 9
The relevant data for Uri Power Station (UPS). Table 9
The maximum possible measurement of errors in various parameters of present investigation. Table 8
The maximum possible measurement of errors in various parameters of present investigation. Table 8
Fig. 9. Effect on erosion rate with the change in Curvature Radius(R¢,,,) for UPS and JHC.
Fig. 9. Effect on erosion rate with the change in Curvature Radius(R¢,,,) for UPS and JHC.
Fig. 8. Geometrical factor (f(a))effect vs normalised radius of curvature (R;,,). Average Value at outlet of runner blade = 9.2 mm.
Fig. 8. Geometrical factor (f(a))effect vs normalised radius of curvature (R;,,). Average Value at outlet of runner blade = 9.2 mm.
Fig. 10. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(Kg/RS?) at normalized radius of curvature(R;,,) of 0.25.
Fig. 10. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(Kg/RS?) at normalized radius of curvature(R;,,) of 0.25.
Erosion rate contour lines with the change in Relative Velocity and (PL)*(K/(RS)?) at normalised radius of curvature(R_ ) of 0.7 Fig. 11. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(Kg/RS?) at normalized radius of curvature(R;,,) of 0.75.
Erosion rate contour lines with the change in Relative Velocity and (PL)*(K/(RS)?) at normalised radius of curvature(R_ ) of 0.7 Fig. 11. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(Kg/RS?) at normalized radius of curvature(R;,,) of 0.75.
Fig. 12. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(K,/RS?) at normalized radius of curvature(R¢,,) of 1.25.
Fig. 12. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(K,/RS?) at normalized radius of curvature(R¢,,) of 1.25.
Fig. 13. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(Kg/RS?) at normalized radius of curvature(R¢,,) of 5 with the corresponding erosion rate values for UPS and JHC.
Fig. 13. Effect on erosion rate with the change in relative velocity (V,) with the change in (PL)*(Kg/RS?) at normalized radius of curvature(R¢,,) of 5 with the corresponding erosion rate values for UPS and JHC.
Fig. 14. Effect on erosion rate with the change in characteristic velocity (W) with the change in (PL)*(Ky/RS?) at normalized radius of curvature(R¢,,,) of 5 with the corresponding erosion rate values for UPS.
Fig. 14. Effect on erosion rate with the change in characteristic velocity (W) with the change in (PL)*(Ky/RS?) at normalized radius of curvature(R¢,,,) of 5 with the corresponding erosion rate values for UPS.
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