120404036 Dukor Kenechi Franklin Governor

RESEARCH ON HARTNELL GOVERNORS

University of Lagos, Akoka

Hartnell Governors

Dukor Kenechi Franklin

Mechanical Engineering

120404036

Author Note

The research on Hartnell Governor was performed on the November 28 th 2014 by

Dukor Kenechi Franklin and other members of Group 2. The research was carried

out at the Pan Ocean Oil Company, Agbara, Lagos. Nigeria.

This research project wouldn’t be a success without the help of the Operations

Engineer, Engineer Oghale.

Phone number(s): +2348031157806, +2348084717793.

E-mail: [email protected], [email protected]

Dukor Kenechi Franklin, Department of Mechanical Engineering, 120404036, [email protected], Group 2.

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mailto:[email protected]




TABLE OF CONTENT

Abstract 3

Reference 4

Figures 5

Nomenclature 7

Introduction 8 Background 9

Experimental Procedure 13

Discussion/Results 14

Industrial Application of Governor 15

Recommendation 18

Conclusion 18


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I. Abstract

The research was performed to study the operation of a hartnell governor. The device used for

the research was an electrical governor in a gas plant.

The plant was set into operation and the effects of the governor on the speed of steam flow I the

plant was observed and noted.

Other effect of the governor on the plant were also discussed such as the sensitivity, variation of

the governor speed with different load, and the governor stability.

Governors as I have learnt has many application in the industry such as: oil companies,

automobiles, aviation, some electronics

This research has research has really made me understand the importance of speed regulation in

devices.


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II. References[1] L.P Wheeler, (1947), "The Gibbs Governor for Steam Engines, New York: Henry Schuman, pp. 63-

78

[2] R.S Khurmi.”Theory of Machines”, New Delhi, S.Chand. Chapter 18.

[3] WIKIPEDIA: http://en.m.wikipedia.org/wiki/Governor

[4] http://www.p-a-hilton.co.uk/products/HTM71-Governors-Apparatus


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http://en.m.wikipedia.org/wiki/Governor


III. Figures


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Picture of the governor used in the steam plant


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IV. Nomenclature

(Nomenclature entries should have the units identified)

m= Mass of each ball in kg,

M = Mass of sleeve in kg,

r1 = Minimum radius of rotation in meters,

r2 = Maximum radius of rotation in meters,

ω1 = Angular speed of the governor at minimum radius in rad/s,

ω2= Angular speed of the governor at maximum radius in rad/s,

S1= Spring force exerted on the sleeve at ω1 in newton,

S2= Spring force exerted on the sleeve at ω2 in newton,

FC 1= Centrifugal force at ω1 in newton =m(ω1)2 r1,

FC 2= Centrifugal force at ω2 in newton =m(ω2)2 r2,

s = Stiffness of the spring or the force required to compress the spring by one mm,

x = Length of the vertical or ball arm of the lever in metres,

y = Length of the horizontal or sleeve arm of the lever in metres, and

r = Distance of fulcrum Ofrom the governor axis or the radius of rotation when the governor

is in mid-position, in meters.


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V. Introduction

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. On the other hand, 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.

A little consideration will show, that when the load increases, the configuration of the governor

changes and a valve is moved to increase the supply of the working fluid ; conversely, when the

load decreases, the engine speed increases and the governor decreases the supply of working

fluid.

Types of Governors

The governors may, be classified as

1. Centrifugal governors,

A. Hartnell Governor

B. Watt Governor

C. Porter Governor

D. Proell Governor

2. Inertia governors


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A. Background

HARTNELL GOVERNORS

A Hartnell governor is a spring loaded governor as shown in the figure below. It consists of

two bell crank levers pivoted at the points O,O to the frame. The frame is attached to the

governor spindle and therefore rotates with it. Each lever carries a ball at the end of the vertical

arm OB and a roller at the end of the horizontal arm OR.

Hartnell Governor


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A helical spring in compression provides equal downward forces on the two rollers through a

collar on the sleeve. The spring force may be adjusted by screwing a nut up or down on the

sleeve.

Sensitiveness of Hartnell Governors

Consider two governors A and B running at the same speed. When this speed increases or

decreases by a certain amount, the lift of the sleeve of governor A is greater than the lift of the

sleeve of governor B. It is then said that the governor A is more sensitive than the governor B.

In general, the greater the lift of the sleeve corresponding to a given fractional change in

speed, the greater is the sensitiveness of the governor. It may also be stated in another way that

for a given lift of the sleeve, the sensitiveness of the governor increases as the speed range

decreases. This definition of sensitiveness may be quite satisfactory when the governor is

considered as an independent mechanism. But when the governor is fitted to an engine, the


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practical requirement is simply that the change of equilibrium speed from the full load to the no

load position of the sleeve should be as small a fraction as possible of the mean equilibrium

speed. The actual displacement of the sleeve is immaterial, provided that it is sufficient to change

the energy supplied to the engine by the required amount. For this reason, the sensitiveness is

defined as the ratio of the difference between the maximum and minimum equilibrium speeds to

the mean equilibrium speed.

Stability of GovernorsA 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.

Isochronous GovernorsA governor is said to be isochronous when the equilibrium speed is constant (i.e. range of

speed is zero) for all radii of rotation of the balls within the working range, neglecting friction.

The isochronism is the stage of infinite sensitivity.

Let us consider the case of a Porter governor running at speeds N1 and N2 r.p.m.

(N1)2=

m+ M2

(1+q)

m∗895

h1

` …. (1)

(N2)2=

m+ M2

(1+q)

m∗895

h2

` …. (2)


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For isochromism, range of speed i.e.N2−N1=0∨N 2=N . Therefore from equations (i) and

(ii), h1=h2 , which is impossible in case of a Porter governor. Hence a Porter governor cannot be

isochronous.

Now consider the case of a Hartnell governor running at speeds N1 and N2 r.p.m. We have

discussed in Art. 18.8 that

M . g+S1=2FC1∗x

y=2∗m( 2π N1

60 )2 r1∗x

y … (3)

M . g+S2=2FC2∗x

y=2∗m( 2π N2

60 )2 r 2∗x

y… (4)

For isochronism, N2= N1. Therefore from equations (iii) and (iv),

M . g+S1

M . g+S2

=r1

r2

Graph showing the points of stability, instabilty and isochronisim in a governor


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VI. Experimental Apparatus/Procedures

The Research Design is to Study the stability, sensitivity and governor effect and to

understand its importance and application in industry today.

ApparatusThe research design was carried out with the following devices;

i. Electrical Governor- It works with the engine system manager at the gas plant

Procedure

1. I ensured that I put on all necessary safety wears before proceeding in to the industry

2. I ensured that all connection in the gas plant were correctly fixed to prevent damages

3. I then put on the plant and observed the way the electrical governor controls the speed of

steam flow as it works with the engine system manager.

4. Pictures of the device were taken for records.

5. I then switched of the controls and then put off the plant.


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VII. Discussion/ResultsFrom the experiment we performed we noticed that the governor increases in speed due to

reduction in load of engine, this results in the fly balls being forced out by a centrifugal force that

is moving the sleeve against the spring tension.

As the fly ball moves out, the central sleeves will be forced upward. This will in turn move

the bell crank, valve rod and control valve in the correct direction to minimize steam flow. This

will therefore decrease the speed back to its normal operating speed.

This speed regulation is of great importance in devices as it gives the operator the ability to

control the rate at which some operations are carried out and


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VIII. Industrial Applications of Hartnell Governor

Generally, governors find application in various areas of the industry. Some of these areas

are:

i.Aircrafts

ii.Small Engine

iii.Vehicles

iv.Computing

AIRCRAFTSAircraft propellers in cooperate the method of governors; the governor senses shafts rpm, and

adjusts or controls the angle of the blades to vary the torque load on the engine. Thus as the

aircraft speeds up (as in a dive) or slows (in climb) the RPM is held constant.

SMALL ENGINESSmall engines, such as used to power lawn mowers, portable generators and lawn and garden

tractors, are equipped with a governor to fuel limit the engine to a maximum safe speed when

unloaded and to maintain a relatively constant speed despite changes in loading.

VEHICLESGovernors can be used to limit the top speed for vehicles, and for some classes of vehicles

such devices are a legal requirement. They can more generally be used to limit the rotational

speed of the internal combustion engine or protect the engine from damage due to excessive

rotational speed.


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i. CarsToday, BMW, Audi, Volkswagen and Mercedes-Benz limit their production cars to 250

kilometers per hour (155 mph). Certain Quattro GmbH and AMG cars and the

Mercedes/McLaren SLR is an exception.

The BMW Rolls-Royces are limited to 240 kilometers per hour (149 mph). Jaguars, although

British, also have a limiter. As do the Swedish Saab and Volvo on cars where it is necessary.

ii. MopedsMopeds in the United Kingdom have had to have a 30 mph (48 km/h) speed limiter since

1977.

Most other European countries have similar rules.

iii. Public services vehiclesPublic service vehicles often have a legislated top speed. Scheduled coach services in the

United Kingdom (and also bus services) are limited to 65 mph.

Urban public buses often have speed governors which are typically set to between 65

kilometers per hour (40 mph) and 100 kilometers per hour (62 mph).

iv. Trucks (HGVs)All heavy vehicles in Europe and New Zealand have law/by-law governors that limit their

speeds to 90 kilometers per hour (56 mph) or 100 kilometers per hour (62 mph).

COMPUTINGThe Linux kernel has a number of CPU frequency governors which are a sort of policies that

set the CPU frequency based on the selected governors and wage patterns. For example, when

the performance governor is active, the CPU frequency will be set to its minimum value, the


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power save governor sets the CPU to its lowest frequency, the on demand governor sets the CPU

frequency, depending on the current wage etc.

ELECTRONIC A servo motor is linked to the throttle and controlled by an electronic module that senses

engine speed by counting electrical pulses emitted by the ignition system or a magnetic pickup.

The frequency of theses pulses varies directly with engine speed, allowing the control module to

apply a proportional voltage to the servo to regulate engine speed. Due to their sensitivity and

rapid response to speed changes, electronic governors are often fitted t engine driven generators

designed to power computer hardware as the generators output frequency must be held within

narrow limits to avoid malfunction

GAS PLANTGovernors are used in gas plants to regulate the rate of steam flow in the plant.


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IX. RecommendationThe research was carried out at the Pan Ocean Oil Company, Agbara, Lagos.

Nigeria.

This research project wouldn’t be a success without the help of the Chief Enginner,

Engineer Oghale.

X. Conclusion

From the research work I conducted at Pan Ocean Oil Company, I noticed that the governor is

used to normalize the speed of steam flow in gas plant.

I also came to my knowledge that the isochronous governor is not of practical use because the

sleeve will move to one of its extreme positions immediately the speed deviates from the

isochronous speed.

Looking at the area of sensitivity, this research also made me understand that for a given lift of

the sleeve, the sensitiveness of the governor increases as the speed range decreases.

I have come to conclusion that the need to control the speed of devices with governors is of great

importance in the industry.


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120404036 Dukor Kenechi Franklin Governor