SteaMTurbineS Question Bank
1) Find out the diagram efficiency of an impulse turbine supplied with steam at the rate of 30 kg/min through nozzles. Steam entering the 0 nozzle inlet is at 5 bar and 200 C while the condenser pressure is 0.2 0 bar. Nozzles are inclined at 25 to direction of motion of the blades 0 which are running at speed of 300m/s. Outlet blade angle is 35 . (V=1010m/s, P=210kW, ɳ b=82.3%) 2) Steam is striking on symmetrical blades of impulse turbine at the rate of 0 0.5kg/s with a velocity of 1200 m/s. Nozzle angle is 20 . Blade velocity is 375 m/s and blade velocity coefficient is 0.75. Using geometrical relations only, find out power developed by the turbine. 0 (Ѳ=28.6 , P=246.9kW) P=246.9kW) 0
3) Nozzles inclined at 24 issue steam to the blades of an impulse turbine with a velocity of 1000m/s. Blades are symmetrical and have speed of 400 m/s. Assuming flow over the blades to be frictionless find out inlet blade angle, steam flow rate and power developed by the turbine when axial thrust is 1135 N. (4000kg/hr, 454kW) 4) In stage of an Impulse Turbine, blade of mean diameter 0.8m is rotating 0 at 3000rpm. Steam enters the turbine without shock at 20 with the velocity of 300 m/s. Blade friction factor is 0.86. Assuming blades to be symmetrical find out the power developed when the axial thrust is 140N. (P=358kW) 5) Steam enters a single stage impulse turbine with a velocity of 300 m/s 0 at an angle of 18 . Mean blade velocity is 144 m/s. Friction factor is 0.84 while angle made by relative velocity at inlet is greater than that at 0 outlet by 3 . If the mass flow rate is 20 kg/s find out power developed by the turbine and the blading efficiency. (P=748.8kW, ɳb=83.2%) 6) Find out: i) Steam flow rate, ii) Power Output, iii) Blade Efficiency of an impulse turbine. Steam velocity= 600m/s, Blade speed= 250m/s, Blade
0
0
inlet and outlet angles are 20 and 25 respectively, Axial thrust= 1000 N. Neglect blade friction and assume that steam enters without shock. (m=20kg/sec, P=3.25MW, ɳ b=90.2%) 7) A power plant consisting of Parson’s Reaction Turbine produces 15 kW power consuming 30 tonnes per hour of steam at a certain stage. Steam at that stage is at 1.6 bar and 90% dry. Axial velocity of flow remains constant and is 75% of the blade velocity. The inlet and outlet angles of 0 0 the blade are 35 and 20 respectively. Find out blade velocity and volume of steam flowing per second. 3 (Vb=24.7m/s, v=8.18m /s) 0
0
8) Blade tip angles of a Parson’s Reaction Turbine are 35 and 20 in the direction of motion. Drum diameter is 1 meter and blade height is 100mm. Turbine speed is 250 rpm. At this stage steam pressure is 3 bar and 90% dry. Find mass flow rate of the steam, power developed. (m=6.34kg/s, P=3.88kW) 0
9) In an impulse turbine nozzle angle is 16 and the blade outlet angle is 0 25 . Inlet velocity of steam coming out of nozzles is 720m/s, while the blade velocity is 180m/s. Blade velocity coefficient can be taken as 0.75. Find energy loss due to friction per kg of steam, power developed and the diagram efficiency. (Energy loss=65.13kW, P=158kW, ɳb=61%) 10) A single row of an Impulse Turbine generates 18kWpower in which dry saturated steam at 7 bar is expanded to 0.45 bar with efficiency of 0.85. 0 0 Inlet and outlet angles are 20 and 30 respectively. Blade friction factor is 0.85 and 1.47 kW is lost in blade friction. Steam flow rate is 200 kg/hr. Find power output and dryness fraction of steam at blade exit. (P=13.14kW, x =0.85) =0.85) 11) Mean diameter of impulse turbine is 105 cm and speed is 3000 rpm. 0 Nozzle angle is 18 and blade velocity ratio is 0.42 and Friction factor is 0.84. Angle made by relative velocity at inlet is greater than that at 0 outlet by 3 . Steam enters at the rate of 3 kg/s. Find resultant thrust on the blades and power developed. (F r=1230N, P=192.5kW)
0
12) In a Parson’s steam turbine blade angles at inlet and outlet are 75 and 0 20 respectively. Mean blade diameter is 90 cm and rotor speed is 2000 rpm. Calculate power developed if steam is entering at the rate of 16.4 kg/s and 8% is lost due to leakage. Also find heat drop across the blades if stage efficiency is 80%. (P=160kW, h d=12.2kJ/kg) 13) Steam at 1.5 bar and dryness 0.95 enters a reaction turbine. Discharge 0 angles for both fixed and moving blades is 20 and axial velocity of steam is 0.7 of the blade velocity. Blade height is 15cm and ring diameter is 1.83 meter. Turbine speed is 500 rpm. Compute power developed. (P=164kW) 14) A reaction turbine running at 360 rpm consumes 5 kg of steam per second. The leakage is 10%. The discharge blade tip angle for both fixed 0 and moving blades is 20 . The axial velocity of flow is 0.75 times the blade velocity. The power developed by a certain pair is 4.8 kW where pressure is 2 bar and dryness 0.95. Find the drum diameter and blade heights. (D=931mm, h=83mm) 15) A 50% reaction turbine runs at 3000 rpm with mean blade velocity 0 120m/s. The velocity ratio is 0.8 and exit angle of blades is 20 . If the mean blade height is 30mm and steam condition is 2.7bar and 0.95 dry, find out power developed by the turbine. Consider blade tip leakage loss as 10%. (m=6.5kg/s, P=124.8kw) 16) In a De Laval turbine, the steam is issued from the nozzles with a 0 velocity of 850 m/s with nozzle angle of 20 . Mean blade velocity is 350 m/s and the blades are equiangular. Friction factor is 0.8. Steam flow rate is 1000kg/min. Determine axial thrust on blades, power developed in kW, blade efficiency. (F a=500N, P=4666.7kW,ɳb=77.5%) 0
17) In an impulse turbine, the nozzles are inclined at 20 to the direction of motion of the blades. Steam leaves nozzles at 375 m/s. Blade speed is 165m/s. Find inlet and outlet angles so that there is no axial thrust. Friction factor is 0.85. Also find the diagram 0 0 efficiency.(34 ,41 ,ɳb=75.66%)
18) Steam enters blade row of impulse turbine with a velocity of 600 m/s at 0 an angle of 25 to the plane of rotation of the blades. The mean blade 0 speed is 255 m/s. Exit blade angle is 30 . Blade friction coefficient is 10%. Determine power developed per kg of steam and the diagram efficiency. (P=150.45kW, ɳ b=83.6%) 0
19) The nozzles of an impulse turbine are inclined at 22 to the plane of 0 rotation. The blade angles both at inlet and outlet are 36 . The mean diameter of the blade ring is 1.25 m and the steam velocity is 680 m/s. Determine rpm of turbine rotor and the torque on the rotor for a flow rate of 2500kg/hr. (4580rpm, 290.5Nm) 0
20) In a single row impulse turbine, nozzle angle is 30 and the blade speed is 215 m/s. Steam speed is 550 m/s. Blade friction coefficient is 0.85. Assuming axial exit and a flow rate of 700 kg/hr, find out absolute velocity of steam at exit and power output. (V 1=243m/s, P=19.8kW) 0
21) Nozzles release steam with a velocity of 1000 m/s at an angle of 24 on a single stage of an impulse turbine. Mean blade speed is 400m/s. Assuming blades to be symmetrical, find out force exerted on the blades in the direction of their motion and power output when steam flows at the rate of 40000 kg/hr. (Ft=1135N, P=4540kW) 22) In a 50% reaction turbine stage running at 3000 rpm, the exit angles are 0 0 30 and the inlet angles are 50 . The mean diameter is 1 m. The steam flow rate is 10000 kg/min and the stage efficiency is 85%. Find specific enthalpy drop and the % increase in relative velocity of steam as it flows over the moving blades. Also determine the power output. (P=11.6MW, hd=82kJ/kg, 52.2%) 23) In a 50% reaction turbine, blades are identical in shape. Outlet angle of 0 moving blades is 19 and absolute discharge velocity of steam is 100m/s 0 in the direction at 100 to the motion of blades. If the steam flow rate is 15000 kg/hr, calculate the power developed by the turbine in kW. (P=327.5kW)
0
24) In a Parson’s Reaction turbine outlet blade angle is 20 and axial flow velocity is half of the blade velocity. Mean diameter is 710 mm and speed of rotation is 3000 rpm. Find inlet angle of blades for shock less entry. If blade height is 64 mm and pressure of dry saturated steam is 0 5.6 bar, calculate power developed. (50 , P=516.9kW) 25) In a Parson’s steam turbine, the blade speed is 66 m/s and the flow of steam is 4 kg/s dry saturated at 1.4 bar. Inlet and outlet angles of the 0 0 blades are 35 and 20 respectively. Calculate required blade height th which is to be 1/10 of ring diameter, power developed and heat drop required by the pair if steam expands with efficiency of 80%. (h=55mm, P=57kW, 71.3kJ/s) 26) Mean blade speed of a reaction turbine is 60m/s. Steam condition is 3.5 0 bar at 175 C. Inlet and outlet angles for both fixed and moving blades is 0 0 th 30 and 20 respectively. Find blade height if it is to be 1/10 of the rig diameter, power developed by the pair and enthalpy drop for stage efficiency of 85%. (h=64mm, P=218kW, h d=19.1kJ’kg) 27) 50% reaction turbine running at 400 rpm has the exit angle of the 0 blades as 20 and the velocity of steam relative to the blades at exit is 1.35 times the mean blade velocity. Steam flows at the rate 8.33 kg/s 3 and at a certain stage specific volume is 1.318 m /kg. Calculate blade height assuming rotor diameter 12 times the blade height and diagram work. (h=138mm, W=153.14Nm/s) 0
28) In an impulse turbine nozzles are inclined at 24 to the plane of rotation of the blades. Steam speed is 1000m/s and blade speed is 400 m/s. Assuming equiangular blades determine axial and tangential thrusts and power developed for flow of 1000kg/hr.(F a=0N, Ft=1.135kN, P=113.5kW) 29) For a single stage of impulse turbine, the nozzles discharge the steam at 0 an angle of 25 to the plane of rotation of blades. The steam leaves with 0 an absolute velocity of 300 m/s and 120 to the direction of rotation of blades. Blades are equiangular and have no axial thrust. Find out power output per kg of steam and the diagram efficiency. (P=144kW,ɳ b=76.2%)
0
30) Steam at 7 bar and 300 C expands to 3 bar in an impulse turbine. Nozzle 0 angle is 20 and the blades have equal inlet and exit angles. The turbine operates with optimum blade speed. Assuming isentropic efficiency of nozzles as 90% and velocity at nozzle entry to be negligible, obtain the 0 blade angles and mass flow required to generate 50kW. (36 , m=0.317kg/s) 31)
For a single row impulse turbine : Mean blade ring diameter= 2m, 0 Speed= 3000rpm, Nozzle angle= 18 , Velocity ratio= 0.5, Blade friction 0 factor= 0.9, blade angle at exit= 3 more than at inlet, steam supply=30000kg/hr. Determine: 1.Power developed 2.Diagram efficiency 3.Steam consumption in kg/kWhr. (P=1387.16kW, ɳb=84.3%, 21.6kg/kWhr)
32)
For a single row impulse turbine : Steam velocity= 500m/s, Blade 0 0 speed= 200m/s, Nozzle angle= 20 , Exit angle of moving blades= 25 , Power developed= 560kW. Determine: 1.Steam flow rate 2.The axial thrust 3.Diagram efficiency. (m=5kg/s, F a=200N, ɳb=89.6
