Kaplan Turbine MCQ Quiz in मल्याळम - Objective Question with Answer for Kaplan Turbine - സൗജന്യ PDF ഡൗൺലോഡ് ചെയ്യുക

Explanation:

The specific speed of a turbine is defined as, the speed of a geometrically similar Turbine that would develop unit power when working under a unit head (1m head). Is prescribed by the relation  \({N_s} = \frac{{N\sqrt P }}{{{H^{\frac{5}{4}}}}}\)

• Low specific speed turbine: The specific speed is less than 50. (varying from 10 to 35 for single jet and up to 50 for a double jet) Example: Pelton wheel turbine
• Medium-specific turbine: The specific speed varies from 50 to 250. Example: Francis turbine
• High specific turbine: the specific speed is more than 250. Example: Kaplan or propeller turbine

Explanation:

Classification of turbines on the various basis is given in the table below:

∴ The most suitable answer is option 3.

Concept:

Impulse Turbine: If at the inlet of the turbine, the energy available is only kinetic energy, the turbine is known as impulse turbine. e.g. a Pelton wheel turbine.

Reaction Turbine: If at the inlet of the turbine, the water possesses kinetic energy as well as pressure energy, the turbine is known as a reaction turbine. e.g. e Francis and Kaplan turbine.

Tangential flow turbines: In this type of turbines, the water strikes the runner in the direction of the tangent to the wheel. Example: Pelton wheel turbine

Radial flow turbines: In this type of turbines, the water strikes in the radial direction. accordingly, it is further classified as

• Inward flow turbine: The flow is inward from periphery to the centre (centripetal type); Example: old Francis turbine
• Outward flow turbine: The flow is outward from the centre to periphery (centrifugal type); Example: Fourneyron turbine

Axial flow turbine: The flow of water is in the direction parallel to the axis of the shaft. Example: Kaplan turbine and propeller turbine

Concept:

• If the water flows parallel to the axis of rotation of the shaft, the turbine is known as an axial flow turbine.
• For the axial flow reaction turbine, the shaft of the turbine is vertical.
• The lower end of the shaft is made larger which is known as a hub or boss.
• When the vanes on the hub are adjustable then the turbine is known as the Kaplan turbine and when the vanes are fixed to the hub then the turbine is known as the Propeller turbine.
• Kaplan turbine is a low head axial flow turbine with an adjustable vane.
• In a Kaplan turbine, the velocity of flow through the rotor constant.

Classification of turbines on various bases is given in the table below:

Concept:

Kaplan turbine is an axial flow reaction turbine in which the water flows parallel to the axis of rotation of the shaft. For Kaplan, both the kinetic and potential energy is available at the inlet.

Kaplan turbine has adjustable moving blades and so it is also known as a variable pitch propeller turbine.

Axial flow reaction turbine has less number of blades and thus the friction loss will be lesser and it can work on low head producing high discharge and high specific speed. But this is susceptible to cavitation.

∴ Kaplan turbine is a propeller turbine in which the vanes fixed on the hub are adjustable.

Concept:

• Kaplan turbine is an axial flow reaction turbine in which the water flows parallel to the axis of rotation of the shaft. For Kaplan, both the kinetic and potential energy is available at the inlet.
• Kaplan turbine has adjustable moving blades and so it is also known as a variable pitch propeller turbine.
• Axial flow reaction turbine has less number of blades and thus the friction loss will be lesser and it can work on low head producing high discharge and high specific speed. But this is susceptible to cavitation.

∴ Kaplan turbine is a propeller turbine in which the vanes fixed on the hub are adjustable.

Explanation:

The specific speed of a turbine is defined as, the speed of a geometrically similar Turbine that would develop unit power when working under a unit head (1m head). 

Mathematically it is given by:

 \({N_s} = \frac{{N\sqrt P }}{{{H^{\frac{5}{4}}}}}\)

Classification of turbines on the various basis is given in the table below:

∴ If the specific speed of the turbine is 300, then the turbine should be Propeller wheel turbine, but in options, the suitable answer will be Kaplan turbine

According to the direction of flow through runner, hydraulic turbines can be classified as:

Concept:

Impulse Turbine: If at the inlet of the turbine, the energy available is only kinetic energy, the turbine is known as impulse turbine. e.g. a Pelton wheel turbine.

Reaction Turbine: If at the inlet of the turbine, the water possesses kinetic energy as well as pressure energy, the turbine is known as a reaction turbine. e.g. Francis and Kaplan turbine.

Tangential flow turbines: In this type of turbines, the water strikes the runner in the direction of the tangent to the wheel. Example: Pelton wheel turbine.

Radial flow turbines: In this type of turbines, the water strikes in the radial direction. accordingly, it is further classified as:

• Inward flow turbine: The flow is inward from periphery to the centre (centripetal type); Example: old Francis turbine
• Outward flow turbine: The flow is outward from the centre to periphery (centrifugal type); Example: Fourneyron turbine

Axial flow turbine: The flow of water is in the direction parallel to the axis of the shaft. Example: Kaplan turbine and propeller turbine.

Explanation:

Runaway speed:

The speed of hydraulic turbine if the runner of the turbine is allowed to run freely without any load and with the wicket gates wide opening is known as runaway speed.

For a given type of turbine, Runaway speed differs due to design variations by different manufacturers.

All the rotating parts in the turbine must be designed to withstand the stresses generated from the centrifugal forces at runaway speed.