Lab Manual | Watt and Porter Governor

AIM :-To perform experiment on Watt and Porter Governors to prepare performance characteristic Curves, and to find stability & sensitivity.

APPARATUS USED:- Watt and Porter Governors.

INTRODUCTION & THEORY :- The function of a governor is to regulate the mean speed of an engine, when there are variations in the load e.g. when the load on an engine increases, its speed decreases, therefore it becomes necessary to increase the supply of working fluid. When the load on the engine decreases, its speed increases and thus less working fluid is required. The governor automatically controls the supply of working fluid to the engine with the varying load conditions and keeps the mean speed within certain limits.

The governors may, broadly, be classified as

1. Centrifugal governor
2. Inertia governor

The centrifugal governors, may further be classified as follows :

1. Pendulum type (Watt governor )

2. Loaded type

(i) Dead weight governor (Porter governor and Proell governor)

(ii) Spring controlled governors (Hartnell governor, Hartung governor, Wilson-Hartnell governor and Pickering governor)

Watt Governor :- The simplest form of a centrifugal governor is a Watt governor. It is basically a conical pendulum with links attached to a sleeve of negligible mass. The arms of the governor may be connected to the spindle in the following three ways :

1. The pivot P, may be on the spindle axis.
2. The pivot P, may be offset from the spindle axis and the arms when produced intersect at O.
3. The pivot P, may be offset, but the arms crosses the axis at O.

Porter Governor :- The porter governor is a modification of a Watt’s governor, with central load attached to the sleeve. The load moves up down the central spindle. This additional downward force increases the speed of revolution required to enable the balls to rise to any to any pre-determined level.

OBSERVATION :-

· Mass of the ball (m) = ————-kg.

· Weight of the ball (w)=————Newtons

· Height of the governor (h) = ——- metres

· Minimum equilibrium speed (N₁) = —— r.p.m.

· Minimum equilibrium speed (N₂) = —— r.p.m.

· Frictional force (F) = ————- Newtons

· Mean equilibrium speed (N) = (N₁ + N₂)/2 in r.p.m

· Mass of the central load = ———kg.

· Weight of the central load (W) = ——–N

· Angle of inclination of the arm to the vertical (α ) = ——

· Angle of inclination of the link to the vertical (β ) = ——

CALCULATION :-

• N² = 895/h (For watt governor)

• N² = ((m + M (1+q)/2)/m) x (895/h) (For porter governor ), where, q = tan β/ tan α

 

• Sensitiveness of the governor = 2(N₁ – N₂)/ N₁ + N₂ = 2 (ω₂ – ω₁)/ ω₂ + ω₁
• A governor is said to be stable when for every speed within the working range there is a definite configuration i.e; there is only one radius of rotation of the governor balls at which the governor is in equilibrium. For a stable governor, if the equilibrium speed increases, the radius of governor balls must also increase.

PRECAUTIONS :-

1. Take reading carefully.
2. Measure the angle very carefully.
3. Measure the height of governor carefully.
4. Speed of governor measure accurate.

VIVA – QUESTIONS :-

• What is the function of a governor ? How does it differ from that of a flywheel ?
• State the different types of governors. What is the difference between centrifugal and inertia type governors ?
• Explain the term height of the governor. What are the limitations of a Watt governor ?
• What is the stability of a governor ?
• Define the Sensitiveness of governor.
• Which of the governor is used to drive a gramophone ?
• The power of a governor is equal to———–.
• What is hunt?