SATHYABAMA UNIVERSITY
DEPARTMENT OF AERONAUTICAL ENGINEERING
SUB CODE: 626651 PROPULSION LAB MANUAL
SIXTH SEMESTER
1
SATHYABAMA UNIVERSITY
DEPARTMENT OF AERONAUTICAL ENGINEERING
Lab. Code : 626651: PROPULSION LAB MANUAL
LISTY OF EXERCISES
1.
STUDY OF AIRCRAFT PISTON ENGINE
2.
STUDY OF AIRCRAFT TURBOJET ENGINE
3.
STUDY OF HYBRID ROCKET
4.
STUDY OF SUPERSONIC RAMJET
5.
HEAT TRANSFER BY FORCED CONVECTION
6.
HEAT TRANSFER BY NATURAL CONVECTION
7.
SAYBOLT VISCOMETER
8.
REDWOOD VISCOMETER
9
CLEVELAND FLASH & FIRE POINT APPARATUS (OPEN CUP)
10.
PENSKY MARTENS FLASH & FIRE POINT APPARAUS (CLOSED CUP)
2
SAFETY PRECAUTIONS
Safety in work place is to prevent any impending danger. The lab is equipped with Petroleum product and with so many electrical apparatus. Any An y negli neg li gence gen ce and over ov er conf co nf id ence enc e w ill il l in vite vi te danger dan ger to Equ ipmen ip mentt and personal.
CAUTION
DO NOT OPERATE ANY EQUIPMENT WITH OUT GUIDANCE/ABSENCE OF OF LAB INSTUCTOR INSTUCTOR
1.
PERSONAL SAFETY (i) (ii) (iii) (iv)
2.
Wear correct fitting lab uniform. Avoid growing long hair ( Except girl student) Wear shoes during lab. Be alert while on lab. Test.
EQUIPMENT SAFETY (i) (ii) (iii) (iv) (v) (vi) (vii)
Never attempt to operate the equipment without knowing how to operate it. Never disturb the instrument or gauges when test is on. Do not operate the equipment more than it prescribed limits. Do not attempt to rectify the electrical defect if equipment fails to operate. Do not wear ring, watch, bracelet etc. while operating the lab equipment. After lab test is over do not forget to switch off the the equipment/ power supply. If the student happen to cause any damage to the equipment by his/her negligence the repair/rectification cost to be born by the students
3
EXPERIMENT NO.1 STUDY OF AN AIRCRAFT PISTON ENGINE
AIM:The aim of this study is to understand the construction and working principle of Piston Engine and its associated components with its function. The piston engines are categorized per the cylinder arrangements and lubricating system. (a) (b) (c) (d) (e)
Inline Engine Inverted Engine “V” Engine Radial Engine Horizontally opposed Engine.
All the above categories are differentiated as per the power need. The basic aim of piston engine in aircraft is to produce less/ required thrust with the help of the Propeller. 1)
PROPELLER:-
It is a device which compresses the air on its rotation and sends it to the rear side of the aircraft to act on wing surface to produce lift. 2)
CARBURETOR:-
This is the basic component which draws the air from the atmosphere and mixes the fuel to send it in correct proportion to the engine. The chemical energy contained in the fuel has been converted into heat energy by burning the mixture inside the cylinder. The mixture of air-fuel from Carburetor is conveyed to the Engine cylinder through induction manifold. 3)
CYLINDER:-
This is the place where the air-fuel mixture gets burned to produce the power. The air-fuel mixture drawn from the Carburetor gets inside the cylinder through inlet valve and gets burned inside the cylinder to produce power. The cylinder assembly consists with barrel, cylinder head, inlet valve, exhaust valve, two spark plugs and a piston from Crankshaft through connecting rod.
4
4)
MAGNETO:There are two magnetos in the engine for duel ignition. The magneto is the source of electric supply to the spark plug. The magneto contains rotating armature with primary and secondary coils, which produces high tension electric power. The lead connecting the battery to magneto is called as Low Tension Lead and the lead connecting the magneto to spark plug is called High Tension Lead. The magneto fitted on the left side of the engine supply spark to the all spark plugs fitted at the bottom side of the cylinder and the magneto fitted on the right side of the engine supply spark to all spark plugs fitted at the top side of the cylinder. Each high tension lead have a metal band indicating the cylinder which it belongs. Magneto is coupled to the Engine drive with a VERNIER COUPLING to have the adjustment on magneto timing.
5)
GENERATOR:The generator is coupled to the engine gear train to take the drive. It will run when ever the engine is running, and will generate the electric voltage and send to the aircraft battery for topping up. The aircraft battery will remain with full voltage at all time to meet out re-start/ relight during flying.
6)
STARTER:The starter is the main components which gives the initial rotation to the crankshaft to start the engine. There are many types of starters i.e. Air Starter, Liquid Starter and Electrical Starter. The starter will give rotation till the crank shaft attains the self-sustained RPM of the engine and get disengage itself, and also when starter button is released.
7)
CRANKSHAFT:Crankshaft is the main back-bone of the engine. It transfers the power from the engine to the propeller. The Power generated by the engine cylinder is conveyed to the crankshaft through piston and connecting rod. This is an essential component for power transmission to the propeller. The crank shaft is connected to the cylinder through Crank web, piston pin and piston. Crankshafts are designed to fit the propeller at the front.
8)
LUBRICATION SYSTEM:There are two types of lubrication systems in pis ton engine. 5
(i) (ii)
Wet sump lubrication Dry sump lubrication.
WET SUMP LUBRICATION In the Wet sump lubrication, the lubricating oil is stored in the crank case itself, after lubrication the oil drips down and remains in the crankcase itself. The crank case in this system acts as a reservoir. DRY SUMP LUBRICATION In dry sump system the oil is stored separately in a tank. The oil from the tank is drawn/ is drawn by oil pump due to suction created in the oil pump during its rotation. The oil is supplied to all bearings and cylinder operation under pressure. The used oil drips back to the crankcase and filtered by a scavenge filter before getting pumped out through a Scavenge pump to the oil cooler. The oil cooler is fitted with a Thermostat Switch to measure the oil temperature and cools down the oil. The outlet from the cooler is connected to Oil Tank . The Oil tank is fitted with Baffle plate to prevent surging and also to remove the foam from the incoming oil.
RESULT:
The result of this study about Piston Engine helps to know the performance and utility in specific aircraft.
6
EXPERIMENT NO.2 STUDY OF AN AIRCRAFT TURBOJET ENGINE AIM:-
Even though power produced by piston engine makes the aircraft to fly, during high altitude flying the piston engine aircraft is not efficient since the air density is very low at high altitude, and also not sufficient to meet the requirement of the engine requirement. However the low level (altitude) flying is very efficient by piston engine aircraft, whereas the high altitude flying is efficient by the Turbojet engine only.
JET ENGINE CONSISTS OF THE FOLLOWING:
(a)
Air Intake
(b)
Compressor
(c)
Combustion Chamber
(d)
Burners
(e)
High Energy Ignition Units
(f)
Nozzle Guide Vane ( N G V )
(g)
Turbine
(h)
Exhaust unit.
(i)
Lubrication System
AIRINTAKE:The air from the atmosphere enters through the air intake for the engine operation. The air from the atmosphere is directed to the compressor through
7
static entry guide vane. The air is made to flow in stream lined manner to the compressor blades with out causing turbulence. Static Entry Guide Vane supports and strengthens air intake.
COMPRESSOR:The efficiency of the Turbojet Engine is determined by its air compressibility. There many types of compressors. (j)
Single Stage Single Entry Centrifugal Compressor
(ii)
Single Stage Double entry Centrifugal Compressor.
(iii)
Multi Stage Axial flow compressor
The compressor consist Shaft, Drum and rotor blades. The Stator blades are fitted in the Compressor casing. The blades are made of steel/aluminum alloy as per the requirement. Each row of stator and rotor blades forms one stage. The number of stages is determined by the number of stator and rotor blades. Each row of rotor will have a row of Stator blades to direct the air to the next phase. Each set of Stator Blades row and Rotor Blades row will be called as Stage. The centrifugal compressor does not have more stages than one. The Axial Flow Compressor has many stages. The Stator blades are fitted on the compressor casing itself. The rotor blades are fitted on the rotor disc and the disc are assembled on the rotor shaft. Each blade is designed in Impulse at the root and Reaction at the tip. One third of the blade length from the root will be of Impulse design and the remaining two-third towards the tip will be of reaction design. i.e. the root will have impulse and the tip will have reaction type. COMBUSTION CHAMBER:The combustion chambers are:(a)
Can type
(b)
Annular type
(c)
Can-annular type
Many of the turbojet engines are fitted with Can-Annular combustion chamber only. The air after the compressor enters in to the combustion chambers through the diffuser casing for mixing with fuel. Only 30% of the air enters
8
inside the combustion chambers and the remaining air get added up later. The air enters in side the combustion chambers for burning is called as primary air. The remaining air called as secondary air used for cooling and dilution of the burnt gas to increase the volum etric efficiency. The combustion chambers are interconnected for flame propagation, since only two combustion chambers are fitted with igniters plug for giving initial ignition. The inter connectors helps in equalizing the pressure in all the combustion chambers and also propagates the flame to other combustion chambers. A spring loaded combustion chamber drain is located in the bottom most point of the Engine (Combustion Chamber outer casing). During wet start/ engine stops the excess unburned fuel is drained through this drain. Since it is spring loaded during engine running the internal pressure will be more and do not permit the drain to get open. BURNERS:The fuel supply from the aircraft fuel tank, booster pump, reaches the fuel pump. The fuel from fuel pump enters into Fuel Control Unit (F C U). The fuel control unit only regulates the fuel supply to burner as per required operation of the engine. Each burner is connected from Fuel Control Unit by a common pipe line which is called as primary line and in addition a separate pipe line is connected to each burner from fuel control unit to supply additional fuel when RPM increases beyond 60% (Acceleration). The Fuel Pump will maintain sufficient pressure to prevent Vapor Lock in the fuel system. The fuel control unit is having a accelerator unit which supply fuel during sudden opening of the throttle to prevent starvation of fuel. IGNITOR PLUGS:There are 02 ignitor plugs fitted in the 2 ‘o clock and 7 ’o clock position in the combustion chamber diagonally. The Electrical Supply from the Battery is sent to High Energy Ignition Unit (HEIU). During initial starting the ignitor plugs will ignite the fuel air mixture inside the combustion chamber. Then the flame from that combustion chamber will get propagate to other combustion chamber through inter connectors and get stabilized with pressure in all the combustion chambers. The Ignitor Switch in the Cockpit will be released after the engine attained the self sustained RPM.
HIGH ENERGY IGNITION UNITS
(H.E.I.U)
The High energy ignition units are the Electrical source of supply of spark to the combustion Chamber. The electrical supply from the Battery is taken to the HIEU and multiplied. The spark is supplied through IGNITOR PLUGS.
9
WARNING: NEVER TOUCH THE H.E.I.U FOR TWO MINUTES AFTER ENGINE SWITCHED OFF. OTHERWISE IT WILL GIVE A FATAL SHOCK.
NOZZLE GUIDE VANE The N G V is the unit located in between combustion chambers and Turbine. This will make the exhaust gases to flow uniformly to Turbine Blades , so that the gases are prevented from creating turbulence before Turbine disc. TURBINE:The turbine is the main part of the jet engine which takes the rotation from compressor shaft and in turn rotates the turbine by the velocity of the exhaust gases. The high speed rotation obtained by the turbine disc due to exhaust gases in turn rotates the compressor to the selected speed. The turbine blades are retained to the turbine disc by” fir tree” method of attachment and penned for retention. The turbine blades are designed in Impulse & Reaction type. EXHAUST UNIT:The exhaust unit is the attachment made to the engine rear side to evacuate the exhaust gases away from the aircraft .Further is covered with thermal Blanket to prevent the heat getting transferred to Aircraft Structure. The exhaust unit is a convergent duct (Pipe) to augment the jet velocity .At the end of the exhaust pipe trimmers may be fitted to increase the jet velocity or thrust or may be fitted thrust reversal attachment to reduce the engine thrust during aircraft landing. LUBRICATION SYSTEM: Dry sump lubrication system is employed in the jet engine. The lubricating oil after lubrication is taken back to the oil tank through oil filter, oil scavenge pump, oil cooler to the tank. The lubricating oil after lubrication to the rear bearing is not taken back to the oil tank since the oil might have lost its property due to high temperature. This is called as “Total Loss Lubrication”. The oil after lubrication to the rear bearing is let off to atmosphere along with exhaust gases. RESULT: 10
The study has given the detailed idea about construction, operation and working principle of Turbojet Engine. This basic study will help in long way to study about any other Jet propelled Aircraft/Space craft/Space shuttle.
EXPERIMENT NO.3 STUDY OF HYBRID ROCKET AIM:It is to study the Hybrid rocket propulsion system and its components. APPARATUS REQUIRED Meter Scale Vernier scale Description and working Principle: · ·
The main components of Hybrid Rocket are: Setting chamber Combustion Chamber Nozzle section Here the propellant is a combination of Fluid Oxidizer (O 2 Gas)& solid fuel (Poly Propylene ). O2 is connected to the setting chamber. · · ·
The setting chamber consists of an ignitor which is the coil made of nickelchromium alloy around the mixture of chamber powder& ammonium phasparate. When the battery is switched “ON” the mixture gets ignited. This flame propagated by high pressure oxidizes into the co mbustion chamber. As the result of the combustion a high pressure gas is produced and passes through the convergent/ divergent nozzle to produce thrust. Further studies on burning rate of fuel can be made by measuring the thickness of the fuel rod after the Oxygen is stopped. DIMENSIONS Setting Chamber---------------------- Diameter-------------------- 97.60 mm
11
Length ---------------------- 87.25 mm Combustion Chamber--------------- Outer Diameter------------ 97.60 mm Inner Diameter------------ 64.30 mm Length --------------------- 194.00 mm Fuel iod----------------------------------Outer Diameter------------64.30 mm Inner Diameter------------35.90 mm Length-----------------------182.25 mm Convergent/ Divergent Nozzle : Convergent diameter--- 61.60 mm Divergent
diameter -- 52.50
mm Length--------------------- 99.10 mm Result : Thus the working of hybrid rocket propulsion system is studied.
EXPERIMENT NO.4 STUDY OF SUBSONIC RAM JET AIM:It is to study the subsonic ramjet and its components. Apparatus Required: Meter Scale Vernier Scale Description and Working Principles: ·
·
When the flight speed of a Turbojet Engine is very high, i.e. in the range of Mach No. 2 to 4, the pressure raise in the diffuser is very high. At this situation of the flight speed, the discharge to the compressor, the total static press ure raise is significant. Therefore it can be removed from the engine along with its prime moves the turbine. Main Components of Supersonic Ramjet Diffuser Combustion Chamber Nozzle · · ·
12
The diffuser decreases the velocity of the incoming air to sufficiently low value, so that addition of required quantity of heat is possible before chockin g. The diffuser consists of number of fuel inlets. The fuel gets mixed with incoming air in the diffuser and attains a very high pressure while entering the c ombustion chamber. On combustion the high pressure and temperature the g as expands to very high velocity while leaving the nozzle. A high thrust is d eveloped on account of large change in momentum flux into the engine. Dimensions: Diffuser:
Combustion Chamber:
Nozzle:
Inlet Diameter------------------50.00 mm Outlet diameter---------------127.30 mm Length -------------------------- 285.00 mm Diameter------------------------ 127.30 mm Length ------------------------- 205.00 mm Inlet Diameter--------------- 127.30 mm Outlet diameter------------- 65.00 mm Length ------------------------- 263.50 mm
RESULT: Thus the working principle of the subsonic ramjet engine is studied.
EXPERIMENT NO.5 HEAT TRANSFER BY FORCED CONVECTION AIM:To determine the temperature distribution across pin-fin due to heat transfer by forced convection. DESCRIPTION:The apparatus consist of a Pin-Fin placed inside an open duct (one side open) and the other end of the duct is connected to suction side of the blower. The delivery side of the blower is taken through the g ate valve and orifice meter to the atmosphere. The flow rate can be varied by th e gate valve and can be measured by the mercury “U” tube monometer connected to the orifice meter. A heater is connected to one end of the Pin-Fin and five thermocouples are connected at equal distances all along the length of the fins the sixth thermocouple is left in the duct.
13
The panel on the apparatus consists of a Voltmeter, ammeter, digital temperature indicator, dimmer to control the power input to heater, thermocouple selector switch,’U’ tube monometer, neon indication lamp and a schematic diagram. OPERATION:i) Connect the 3 pin plug to a 230V, 50 Hz, 15 Amps power socket. The indicator lamp is ” ON.” (ii)
Keep the Thermocouple selector switch in ZERO position.
(iii) Turn the Dimmer knob clock wise and set power input to the heater to any desired value by looking at the voltmeter & amm eter. (iv)
Allow the unit to stabilize.
(v)
Switch ON the blower.
(vi) Set airflow rate to any desired value by looking at the difference in mercury ‘U’ tube manometer. (vii) Note down the different temperatures on each step. (viii) Repeat the experiment. (a) Vary the air flow rate by keeping the power input to Heater constant. (b) Varying the power input to the heater and keeping the air flow rate constant. (ix)
Tabulate all the readings and calculate different conditions.
(x) After the knob is clicked” OFF” and thermocouple selector switch is turned” OFF” to ZERO after the experiment is over. Tabular column
VALVE POSITION
MANOMETER READING HM (cm)
H1
H2
POWER SURFACE (Pin Fin) TEMPERATURE IN °C
VOLTS AMPS (V) (A)
T1
T2
T3
T4
Ts ° C
AMBIENT TEMP (T6) °C FIN
T5
14
First Test Second Test Third Test
Observation: Duct Size (a X b) Diameter of the fin D Diameter of the Orifice (d) Length of the fin (L) Co-efficient of discharge of Orifice meter
= 0.15 X 0.10 m = 0.012m = 0.02m = 0.15m = 0.61
CALCULATION: 1. Experimental heat transfer Co-efficient q hexpt = ------------------ As (Ts-Ta) q = v x a; v = Voltage ; a = ammeter reading As = ЛDL Where (D) = Diameter of the fin (L) = Length of the fin T1+T2+T3+T4+T5 Ts = -------------------------------; Ta= T 6 = Ambient Temp. 5
ρ M 2.
H A
= HM
X
----------------
ρ A (ρ a)N.T.P X 273 (ρa )R.T.P. 1000Kg/m3
3.
= ------------------------;
ρ M (Density of mercury)
273 + room temp in oC
Volume flow rate of air through the duct Q = Cd a (2g H A) ½ a = Л (D) 2/ 4 Cd = 0.61
4.
= 13.6 X
where D = Diameter of the orifice
Velocity of air through the duct V= Q/ A ; where A = Area of Duct (a x b)
15
5.
Velocity of air at T mf V Vmf = ---------------- X T T
6.
mf
; Where T mf =
T s __ T ambient ____________
Ambient
Vmf X D e Reynolds number Re = -----------v Where D e = 4 x a x b -------------2 (a + b)
2
Find out v, k, Pr values from H.M.T. table for the corresponding temperature T mf
v = Kinematic Velocity k =Thermal conductivity of Air ; P r = Pranatl number 7.
Theoretical heat transfer coefficient N u k h theo =-----------D Where D = Diameter of the fin k = Thermal conductivity of Air N u = Nusselt number Find out Nusselt number from H.M.T. table for range of Re, P r 8.
9.
10.
Theoretical Heat Transfer Q = {h theo X C X k X A } ½ X ( T1- Ta) X T anh ( m X L ) Where C = Л D; D f = Diameter of fin; L = Fin Length Kf (Brass) = 110.7 W ( m.K) T 1 = Temperature where the first thermocouple is fixed m = { htheo X C / Kf X Af } ½ D == Diameter of the fin Where A = Л D 2/4 Efficiency of the Fin = T an h (mL) -----------------; L = Fin Length mX L T x --- T a ------------T 1 -- Ta Ta Tx
=
Cosh {m (L – X) ----------------------Cosh ( m L )
= Ambient Température ; X = Thermocouple position = Temperature at X distance
Graph: - Distance between the thermocouple and the base of the fin Vs Experimental temperature has been plotted. 16
Distance between the thermocouple and the base of the fin Vs Theoretical temperature has been plotted. RESULT: The temperature distribution was determined across pin fin due to heat transfer by forced convection.
EXPERIMENT NO.6 HEAT TRANSFER BY NATURAL CONVECTION AIM: To determine the temperature distribution across pin fin due to heat transfer by natural convection
DESCRIPTION:The apparatus consists of a pin fin placed inside an open duct (one side open). A heater is connected to one end of the fin and five thermocouples are connected at specified distances along the length of the fins. The sixth thermocouple is left in the duct.
17
The panel on the apparatus consists of a voltmeter, ammeter, digital temperature indicator, dimmer to control the power input to heater, thermocouple selector switch, neon indicating lamp and a schematic diagram. OPERATIONS: 1. 2. 3. 4. 5. 6. 7. 8.
Connect the 3-pin plug to a 230 V, 50 HZ, 15 Amps power socket. The indicator lamp is “ON”. Keep the thermocouple selector switch in ZERO position. Turn dimmer knob clockwise and set power input to the heater to any desired value by looking at the voltmeter and ammeter. Allow the unit to stabilize. Note down the different temperature position. Repeat the experiment by varying the power input to the heater. Tabulate all the readings and calculate different conditions. After the knob is clicked OFF and thermocouple selector switch is turned OFF to zero after the experiment is over. TABULAR COLUMN
Sl.No.
POWER
VOLTS AMPS (V) (A)
SURFACE (Pin-Fin) TEMPERATURE IN ° C T1
T2
T3
T4
TS °C
AMBIENT TEMP( T 6 ) °C
ŋ FIN
T5
OBSERVATION Duct Size (a x b)
= 0.15 X 0.10 m
Diameter of the fin D
= 0.012 m
Diameter of the Orifice (d)
= 0.02 m
Length of the fin ( L )
= 0.15 m
Coefficient of discharge orifice meter
= 0.61
CALCULATION: 1. Experimental heat transfer coefficient:18
q h expt = --------------- As (Ts-Ta) q= v x a ; v = Voltage As = Л DL Where (D) = Diameter of the fin
; a = Ammeter reading
T 1 + T2 + T3 + T4 + T 5 (L) = L engt h of th e Fin ; Ts = ------------------------------- ; Ta= T6= Ambient Temperature
5
3
2.
gL β d T =---------------v2
Grashof Number (Gr)
Where g
= 9.81 m/ s2
1 Co-efficient of volume expansion β = -----------T f + 273 T s + T a T f = ---------------------- in ° c ; L = 500 x 10 -3 2 dT = T s - T a v = Kinematic Viscosity. Find out values v, k, P r from H.M.T Table from the corresponding temperature T f . 3. Use of empirical relation: (a) For 104 ≤ Gr Pr ≤ 10 8 , Nu = 0.56 (Gr. Pr )
0..25
h theo L ------------- = Nu k (b) For10
8
≤ Gr Pr ≤ 10
12
,Nu = 0.13 (gr.Pr)
h theo L ----------- = Nu K k = Thermal conductivity of Air
h
theo
=
0.33
Theoretical heat transfer coefficient
L = 500 x 10 -3 ; Pr = Prandtl number
L (m)
h theoretical W/ ( m 2 .K )
19
Find out v,k, P, Values from H.M.T Table for the corresponding temperature T mf v = Kinematic Viscosity k = Thermal conductivity of air P r = Prandtl number
4.
Theoretical heat transfer coefficient
h theo = N u k Where D = Diameter of Fin -------k = Thermal conductivity of air D Nu = Nusselt number Find out Nusselt number from H. M. T. Table for range of Re, P r 5. Theoretical Heat Transfer Q = { h
x C x k x A } ½ x ( T 1 - T a ) T anh (m x L ) where C = Л D ; D f = Diameter of fin ; Kf ( Brass ) = 110.7 W ( m.K ) L = Length T 1 = Temperature where the first thermocouple is fixed theo
m = { h theo x C / kf x A f } ½ 2
Where A = Л D /4 D= Diameter of fin
6.
Efficiency of the fin = Tan h (m L)
------------mxL 7.
Tx -Ta -------------T1–Ta
Ta = Tx=
=
L = Fin Length
Cosh { m ( L - X ) } ----------------------------Cosh ( mL)
Ambient Température ; X = Thermocouple position Température at X distance
GRAPH
20
Distance between the thermocouple and the base of the fin Vs Experimental temperature has been plotted. Distance between the thermocouple and the base of the fin Vs Theoretical temperature has been plotted.
RESULT: The temperature distribution was determined across pin fin due to heat transfer by natural convection.
EXPERIMENT NO.7 SAY BOLT VISCOMETER AIM: To determine the viscosity of an oil expressed as a time of flow in seconds through specified hole made in a metallic piece. SCOPE:
21
(a) The method of test shall be used to determine the SAYBOLT viscosity of petroleum products and lubricants.
(b) The SAYBOLT universal viscometer shall be used only for oils with times of flow more than 32 seconds. There is no maximum limit to viscosity to be measured by the SAYBOLT viscometer but in general liquids having an outflow time of the order of 1000 secs and higher. SAYBOLT viscometer are tested more conveniently by means of SAYBOLT FUROL viscometer.
(c) The SAYBOLT FUROL viscometer shall be used only for oils with 0 time of flow more than 25 seconds. The out fl ow of FUROL instrument is approximately one-tenth that of the universal. NOTE: The word FUROL is the contraction of the phrase Fuel and road Oils. TEMPERATURE OF TESTING :
(a) With the SAYBOLT Universal viscometer determinations shall be made at 21° C, 37.5°C, 54 ° C. and 99° C.
(b) With the SAYBOLT FUROL determinations shall be made at 25°C,37.5° C,50° C or 98° C . In tests on road and paving materials, determination may also be made at 60° C and 82 °C.
PROCEDURE: (a) The oil tube shell is first cleaned with an effective solvent , such as benzol and excess solvent shall be removed from gallery . (b) All oil shall pass through a mesh wire strainer before i t is introduced in oil tube. After the tube is cleaned, a quantity of oil to be sufficient to wet the
22
entire surface of the tube shall be poured into the tube and allowed to drain out. The cork stopper shall be inserted not less than 4 inches , not more than 3/8 inch, into the lower end of the cur chamber at the bottom of the oil tube. The cork shall fit tight enough to prev ent the escape of oil, as evidence by the absence of oil on the cork after it is withdrawn. (c) If the test temperature is above that the room, the oil shall be heated more than 20° C below the temperature of the test. In no case, h owever shall be preheated to a temperature above 28° C below the f lash point. The oil shall be poured into the oil tube unit. If ceases to overflow into the gallery, the oil in the oil tube shall be kept well stirred with the oil tube thermometer, care being taken to avoid lifting the outflow tube. The bath temperature shall be adjusted until the oil temperature remains constant. After thermal equilibrium has been attained no further adjustments shall be made in both temperature. (d) After the temperature of the oil in the oil tube has remained co nstant with in 0° C- 1° C of the desired temperature for 1minute with constant stirring , the oil tube thermometer shall be with drawn and the surplus oil removed quickly from gallery by means of the withdrawal tube so that the level of the oil in the gallery is below the level. The tip of the withdrawal tube shall be started over again, if the tip of the withdrawal tube touches the overflow firm. Under no conditions shall be excess oi l be removed by rotating the withdrawal tube around the gallery. (e) The receiving flask shall be placed in position so that the steam of oil from the out let tube will strike the neck of the flask. The graduation marks on the receiving flask shall not be less than 10 cm not more than 13 cm from the bottom of the bath. The cork shall be snapped from its position and at the same instant the timer shall be started or shall be stopped when the bottom of the meniscus of the oil reached the mark on the neck after receiving the flask.
TABULAR COLUMN:
Sl. No
Temperature of oil in ° C
Temperature of water in ° C
Time for 60 ml of oil collected ( in Secs)
23
1 2
CALCULATION: SAYBOLT VISCOMETER Kinematics viscosity
= (At- B/t) Stokes A = 0.0026 B = 1. 88 t = Saybolt Viscosity No. in seconds ρr = Density of oil at room temperature gm/cc Tr = Room Temperature T = Temperature at which the experiment is
conducted. RESULT : The time in seconds is determined by the prescribed procedure, with the Universal (or Saybolt Furol) viscosity of the oil at the temperature at which the test is made. Results shall be reported to the nearest 0.1 seconds for viscosity values 200 seconds and to the nearest whole seconds for values 200 seconds or above. With proper attention to details of method of procedures, results in different laboratories with different operators under refree or standardization condition of testing shall not differ by more than 0.5 percent.
EXPERIMENT NO.8 REDWOOD VISCOMETER AIM:
24
This is used to determine the viscosity of oil expressed as a time of flow in seconds through specified hole made in a metallic piece. SCOPE: The Redwood Apparatus measures viscosity in empirical units and not in absolute units such as centistokes. It is poss ible to convert Redwood viscometer readings to absolute units, for which the specifications IP 70/68 iss ued by the Institute of Petroleum, London may be consulted. The method is primarily applicable for viscosity determination of oil which flows in a Newtonian ma nner that is if it possesses a linear relationship between shearing stress and rate of shear under the test condition. MODE OF OPERATION The flow time measurements for petroleum products should be made at the following temperature:21 °C, 37.8° C, 50 °C , 60° C, 90 °C, 121° C, 149°C, and 204°C For Fuel oils the minimum temperature is 49°C For Flux oils the temperature of test to be 93°C The apparatus REDWOOD, No. 1 will correctly indicate the viscosity flow if it stands between 30 seconds to 2000 seconds. If the flow time measured with this apparatus for any oil exceeds2000 seconds, the test should be repeated with Redwood Viscometer No. 2 which will give the correct value of viscosity for such highly viscous oils. SAMPLING: For determination at temperature of 93°C or lower, heat the samples with out stirring, in the loosely stoppered container filled as completely as possible, for a hour at 100 °C by immersing in a suitable liquid bath maintained at the temperature, e.g. a boiling water bath. Then ad just the temperature of the sample by immersion in a liquid bath the temperature of which is slightly below the below the test temperature. Carryout subsequent heating using a source of heat not higher than 121°C and in no circumstance heat the sample over a flame before pouring the oil into the cup or immersion of hot bodies in it. In determination at temperature of 121°C or higher do not heat the sample to a temperature more than 28°C above that of the test temperature. When a series of viscosities is to be determined at several temperatures, all these may be done on the same sample of oil the determinations at the higher temperatures being and before those at the lower temperatures. Determine the viscosity with in 1 hour of the sample reaching the desired temperatures.
25
PREPARATION OF THE APPARATUS (a)Clean the oil cup with suitable solvent e.g. carbon tetrachloride and then dr y it thoroughly using soft tissue paper, or some similar material which will not leave any fluff. Clean the jet hole by any f ine thread. (b) Set up the viscometer, using the circular spirit level to ensure that i t is in level. Fill the bath with water for determinations at 93°C and below, and for the higher temperature, with oil having a suitably low viscosity at the test temperature. PROCEDURE (a) Heat the viscometer bath to a few degrees above the desired test temperature. Pour the prepared sample into the oil cup through a filter of metal gauge not coarser than BS 100 mesh (152/u). Adjust the temperature of the bath until the sample in the cup maintained at the test temperature, stir the contents of the bath and cup during this process preferably by continuous stirring of the bath. Stir the sample during preliminary period e.g. by means of the ball valve, closing the bottom of the jet by suitable means, but do not stir the sample during the actual determination. When the temperature of the sample has become quite steady at the desired value, adjust the liquid level by allowing the sample to flow out until the surface of the sample touches, the filling point. Place the oil cup, and swing the oil cup thermometer towards the closed end of the curved slot in the cover. Place the clean, dry stamd 50 ml. Flask centrally below the jet, with the top of the neck a few millimeters from the bottom of the jet. Do not insulate the flask in any way, lift the ball valve and simultaneously start time recorder. Suspend the valve from the clip supporting the oil cup thermometer by means of the cook in the wire stemma. Stop the time recorder at the instant the sample reaches the graduation mark of the flask and note the final reading of the oil cup thermometer. (b) Reject any determination if the temperature of the sample in the oil cups various during the run by more than 0.1° C for temperatures of 60° C or below by more than 0.3° C and 93° C or by more than 8.5 °C at 121 ° C.
CALCULATION AND REPORTING Report the time in seconds to the nearest 0.5° C f or the value below 200 seconds and to the nearest whole seconds for value above 200 seconds as the RED WOOD/ SAYBOLT viscosity, IP 70, starting which viscometer was used and the test temperature.
26
TABULAR COLUMN
Sl.No.
Temp. of Oil in Temp. of Water °C in ° C
Time for 60 ml of oil collected (t Sec)
1
2 3 4 Calculations :Kinematic viscosity
= (At- B /t ) Stokes A =
Absolute Viscosity
0.0022
B
= 1.8000
t
=
Redwood Seconds
= Kinetic Viscosity x Density
Draw the following graphs : (i) Temperature vs Redwood Seconds (ii)Temperature vs Kinematic Viscosity (iii)Temperature vs Absolute Viscosity (iv) Temperature vs Density
27
EXPERIMENT NO.9 CLEVELAND FLASH POINT & FIRE POINT APPARATUS ( OPEN CUP ) AIM The aim of this Experiment is to determine the Flash Point & Fire Point of the given oil using Cleveland Flash & Fire point apparatus. Introduction: Mineral oil when heated to a sufficiently high temperature, it decomposes chemically. The hydrocarbons get breaks up into volatile combustible Gas. The Flash point of oil is defined as the temperature to which it must be heated to give off sufficient vapor to form an inflammable mixture with air. The Fire point is the lowest temperature at which the production of combustible gas from the oil is enough to maintain a steady c ombustion after ignition. CLAVELAND APPARATUS :This instrument consists of a brass cup with handle to fill oil for experiment. The cup is placed over an electric heater. The cu p is open to atmosphere. A thermometer is positioned in the clamp provided to find the oil temperature. The test flame is admitted to the oil during heating up. To find out flash point and power point the flame is admitted at a oil periodically. PROCEDURE:1. Clean the oil cup thoroughly and dry it. 2. Fill the oil in the cup to sufficient level to carryout the test.
3. Place the clamp in position to insert the thermometer. 4. Connect the heater to main heater electrical supply and adjust the voltage by control box.
5. When the oil temperature is raising apply the test flame over the oil at certain interval of 20 ° C for finding Flash & Fire Point.
28
TABULAR COLUMN Sl. Room No. Temperature
FLASH POINT IN ° C
FIRE POINT IN ° C
1 2 3 4
REPORT The Flash and Fire point for the given oil in this condition was found to be 48 ° C and 54 ° C.
RESULT : The flash and Fire point of the given oil was determined in open cup condition.
29
EXPERIMENT NO.10 PENSKY MARTENS FLASH POINT & FIRE POINT APPARATUS ( CLOSED CUP ) AIM : This experiment is carried out to determine the Flash and Fire Point of the given oil using Paskey Martens Flash & Fire Point Appar atus. INTRODUCTION :Mineral oil when heated up to a sufficiently high temperature, it gets decompose chemically. The Hydrocarbons breaks into volatile combustible gase s. The Flash Point of oil is defined as the temperature to which it must be heated up to give off sufficient vapour to form an inflammable mixture with air. The Fire Point is the lowest temperature at which the production of combustible gas from the oil is enough to maintain a steady c ombustion after ignition. PENSKY-MARTENS APPARATUS This instrument consists of a brass cup with a filling mark inscribed inside. The cup The cup is surrounded by electrical heating elements. The brass cup is closed with a cover. There are 03 openings in the cover. Thermometer is inserted in one of the openings into the oil. The test flame is admitted through the central hole and stirrer is connected through the other opening. PROCEDURE i)
Clean and dry the oil cup.
ii)
Fill the oil in the cup upto the leveling point.
iii)
Place the lid in the position and insert the thermometer.
iv)
Connect the heater to the main power and adjust the rate of heating by control Box.
30
