Water turbines Billy Gerena # 73656 Robert De Aza # 66880 Jorge Seda # 84012 Jose GarcIa # 69260 Prof: Eduardo Cabrera  (ME 4111-35)

Abstract On this experiment to types of Impulse turbine were analyzed and compared. These two were the Axial, Pelton and Radial impulse turbines. We determined the efficiency for the Axial Flow Impulse Turbine the Pelton Impulse Turbine as well as the Radial Impulsive Turbine.

Outline Introduction Objective Theory Experimental Procedure Reference

Objective To understand the operating characteristics of the reaction and impulse turbines encompassed in their governing mechanical laws that predicts their work and performance. Demonstrate the mechanism of the turbine-speed control in relationship with the various forms of energy explained in the mechanical laws that predicts their behavior.

Introduction A water turbine is a rotary machine that converts kinetic and potential energy of water into mechanical work. Water turbines are mostly found in dams to generate electric power from water kinetic energy. Water turbines take energy from moving water. Flowing water is directed on to the blades of a turbine runner, creating a force on the blades. Since the runner is spinning, the force acts through a distance to produce work. In this way, energy is transferred from the water flow to the turbine.

Theory Water turbines are divided in two groups : Reaction turbines- are acted on by water, which changes pressure as it moves through the turbine and gives up its energy. They must be encased to contain the water pressure or must be fully submerged in the water flow. Impulse turbines- changes the velocity of a water jet that strikes on the turbine’s curved blades, consequently the flow is reversed and the resulting change in momentum causes a force in the turbines. The turbine doesn’t require housing for operation.

Theory In both types of turbines the fluid passes through a runner having blades. The momentum of the fluid in the tangential direction is changed and so a tangential force on the runner is produced. The important feature of the impulse machine is that there is no change in static pressure, across the runner, while for the reaction turbine there are considerable changes in pressure energy.

Theory Applying the first law of thermodynamics (principle of energy conservation) to a “control volume”. Assuming a steady flow operation of the turbine per unit of mass (j/kg). 𝑤𝑠= 𝑝1−𝑝2 𝜌 + 𝑉1 2 − 𝑉2 2 2 +𝑔 𝑍1−𝑍2 +𝑤𝑙𝑜𝑠𝑠 Where ws is the work performed by the fluid on the turbine.

Theory Actual work (wa) is the total useful specific energy supply by the liquid. 𝑤𝑎= 𝑝1−𝑝2 𝜌 + 𝑉1 2 − 𝑉2 2 2𝑔 +𝑔 𝑧1−𝑧2 The total dynamic head of the turbine is described as: 𝐻= 𝑝1−𝑝2 𝑔𝑝 + 𝑉1 2 − 𝑉2 2 2𝑔 +(𝑧1−𝑧2) The hydraulic power (Ph) is the useful power supplied by the liquid to the turbine. 𝑃ℎ=𝜌𝑔𝑄𝐻

Theory The brake power Pb (W) produced by the turbine in creating a torque (Nm) and the rotor speed n (Hz) is given by: 𝑃𝑏=2𝜋∗𝑛∗𝑇 The torque is given by: 𝑇=𝐹𝑏∗𝑟 Where r (m) is the radius of the pulley.

Theory The hydraulic efficiency (Ƞh) is defined as: 𝜂ℎ= 𝑝𝑜𝑤𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑡𝑢𝑟𝑏𝑖𝑛𝑒 𝑟𝑜𝑡𝑜𝑟 𝑢𝑠𝑒𝑓𝑢𝑙 𝑝𝑜𝑤𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑏𝑦 𝑓𝑙𝑢𝑖𝑑 = 𝑃𝑟 𝑃ℎ The mechanical efficiency (Ƞm) is defined as: 𝜂𝑚= 𝑝𝑜𝑤𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑡𝑢𝑟𝑏𝑖𝑛𝑒 𝑟𝑜𝑡𝑜𝑟 𝑝𝑜𝑤𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 𝑏𝑦 𝑡𝑢𝑟𝑏𝑖𝑛𝑒 𝑟𝑜𝑡𝑜𝑟 = 𝑃𝑚 𝑃𝑟

Theory A efficiency expressing the friction losses in the pulley assembly (Ƞb) as: 𝜂𝑏= 𝑝𝑜𝑤𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑏𝑟𝑎𝑘𝑒 𝑝𝑜𝑤𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑡𝑢𝑟𝑏𝑖𝑛𝑒 𝑟𝑜𝑡𝑜𝑟 = 𝑃𝑏 𝑃𝑚 The total efficiency (Ƞt) is defined as: 𝜂𝑡= 𝑝𝑜𝑤𝑒𝑟 𝑎𝑏𝑠𝑜𝑟𝑏𝑒𝑑 𝑏𝑦 𝑏𝑟𝑎𝑘𝑒 𝑢𝑠𝑒𝑓𝑢𝑙 𝑝𝑜𝑤𝑒𝑟 𝑠𝑢𝑝𝑝𝑙𝑖𝑒𝑑 𝑏𝑦 𝑡ℎ𝑒 𝑓𝑙𝑢𝑖𝑑 = 𝑃𝑏 𝑃ℎ = 2𝜋∗𝑛∗𝑇 𝜌𝑔∗𝑄∗𝑇

Theory Turbine characteristics curves shows that at a constant flow rate, the brake power and the total efficiency have a maximum at a specific rotational speed.

Theory Control of impulse turbine speed Although there are many types of impulse turbine design, the most common and easy to understand is the Pelton wheel (FM32). In a Pelton turbine, a high speed jet of water strikes the Pelton wheel buckets tangentially and leaves the buckets with no radial velocity component. The ideal hydraulic energy can be described as: 𝑤=𝑈𝑏 𝑈𝑏−𝑉𝑗 1−𝑐𝑜𝑠𝛽 Where: Ub is bucket speed, Vj is the water jet incoming speed and β is the exit angle of the water jet from the bucket.

Theory In order to maximize the production of power (and the hydraulic efficiency), it is found that Ub=0.5*Vj. Taking into consideration the losses such as hydraulic, mechanical and friction, the maximum measured power is Ub<0.5*Vj.

Theory Flow rate control The pelton turbine unit FM32 has two mechanisms for flow rate control, using the throttle valve and the spear valve. The axial flow turbine FM30 has two mechanism for flow rate control, using the throttle valve and the nozzle valve.

Theory Axial flow turbine unit FM30 behavior chart

Equipment Axial Flow Impulse Turbine. a) Turbine Rotor, b) Schematic of the FM30 unit Turbine Service Unit FM3SU using the Pelton Turbine FM32 Radial Flow Reaction Turbine. (a)Turbine Rotor (b) Schematic of the FM31 unit.

Equipment Data Acquisition System: Data acquisition and computer control of the unit FM3SU, including the unit FM30, FM31, or FM32, is accomplished by using a CAPTURE interface device (IFD) connected to a computer PC IBM lodged with the appropriate software “FM3SU Turbine Service Unit”. You must check all connections from the sensors to the designated channels according to the first screen shot that appears after load the software and select the turbine unit to test.

TASKS AND EXPERIMENTAL Objectives Task No 1: Using Engineering Units: The objective of this first task is to ensure fully understand of measured units of quantity to those of the variables necessary to calculate pump performance. The basic parameters used to define, and therefore measure, turbine performance include: discharge flow rate Q, head H, Torque T, power P, and efficiency n. Also the brake power, the torque, and the turbine efficiency & head. Task No 2: Turbine characteristics: The objective of this task is to obtain the characteristic curves for a turbine operating at a range of fluid flow rates. The characteristic curves are best shown relating Torque, Brake Power, and Turbine Efficiency versus rotational speed for a given turbine running at constant fluid flow rate. Set the flow rate at 100% and 50%. Task No 3: Comparison of nozzle and throttle valve performance in the Axial Flow Impulse Turbine: The objective of this task is to show the difference in performance between throttle control and nozzle control of turbine speed. Specifically, plot Brake Power versus turbine speed for at least three constant flow rates (100%, 75%, and 50%). Task No 4: Comparison of spear and throttle valve performance in the Pelton Turbine: The objective of this task is to show the difference in performance between throttle control and spear valve control of turbine speed. For the Pelton turbine, plot Brake Power versus Turbine speed for at least three constant flow rates (100%, 75%, and 50%).

Tasks and Experimental Objectives Task No1: Using Engineering Units The objective of this first task is to ensure fully understand of measured units of quantity to those of the variables necessary to calculate pump performance. The basic parameters used to define, and therefore measure, turbine performance induce discharge flow rate Q head H, Torque T, power P, and efficiency n. Task No 2: Turbine Characteristics The objective of this task is to obtain the characteristics curve for a turbine operating at a range of fluid flow rates. The characteristics curve are shown relating torque, brake power and turbine efficiency vs rotational speed for a given turbine running at constant fluid flow rate at 100% and 50%. Task No 3: Comparison of nozzle and throttle valve performance in the axial flow impulse turbine The objective of this task is to show the difference in performance between throttle control and nozzle control of turbine speed. Specifically , plot brake power vs turbine speed for at least three constant flow rates (100%, 75% and 50%). Task No 4: Comparison of spear and throttle valve performance in the Pelton Turbine The objective of this task is to show the difference in performance between throttle control and spear valve control turbine speed. For the pelton turbine, plot brake power vs turbine speed for at least three constant