MECHANICAL POWER

Section A : Mechanical and Automobile Engineering – (120) Questions 1.  1.Strength of Materials : (15) Stress and strain, strain energy, shearing force and bending moment, moment of inertia, Principal planes and stresses, slope and deflection. Direct and bending stresses, Columns, Torsion and thin cylinders. 2. Mechanical Technology : (20) 2. Engineering materials, Non chip forming processes, chip Forming process : Turning, Drilling, Milling, Boring, Broaching, Finishing and super finishing, Gear production as well as NC-CNC and non conventional machining methods. 3. Theory of Machines : (20) Kinematics and dynamics of machines, role of friction, different power devices and power transmission equipments such as governers, gyroscopes etc., Applications of cams. 4. Hydraulics : (20) Fluids and their properties, Laminar and turbulent flow, Bernaulli’s Equation, Fluid pressure, Pascal’s Law, Surface tention, fluid flow and its measurement. 5. Thermal Engineering : (20)

Transient heat conduction When temperature of body changes from time to time and With position is called Transient heat conduction. when temperature of body changes uniformly with time is called lumped capacitance system. Criteria for lumped capacitance system: biot no is less than or equal to 0.1

This law is generally related to the conductivity. According to this law Ratio of thermal conductivity and electrical conductivity is the same for all metals at the same temperature and this ratio is directly proportional to absolute temperature.

Centrifugal pump consist of the following parts 1)Inlet and outlet pipe 2)Casing 3)Impeller 4) Vanes. Working principle of Centrifugal pump:  Centrifugal pump creates an increase in pressure by transfer of mechanical energy from the electrical motor to the fluid through the rotating impeller. Inlet and outlet pipe.- One end of the inlet pipe is dipped in to the fluid fitted with a strainar and other end is connected to the casing. Similaraly one end of oulet pipe connected to casing and other to the discharge tub. Casing: Casing is the outermost part of the centrifugal pump. cross sectional area of the pump is goes on increasing along the sdischarge side.casing is generally made up of a stell or cast iron. Impeller- Impeller is the rotating part of the pump.which have vanes for pushing fluids in the casing.sometimes there will be guide vanes are also provided to guide the flow.Impeller is situated in the casing. Working: Suction pipe suck the water fro

Steady flow: the properties of fluid atevery point in the flow do not depend upon time, it is called a steady flow. Unsteady flow: the properties of fluid at every point in the flow do not depend upon time, it is called a unsteady flow. Uniform flow: The flow in which velocity do not change from point to point at any instant of time. Non uniform Flow: The flow in which velocity do change from point to point at any instant of time. Laminar Flow: the motion of the fluid particles of fluid is parallel to the pipe walls.or along a straight line. Turbulent flow: Motion of a fluid partical in zig zhag way ie do not parallel to pipe wall. Compressible flow: The flow in in which density of a fluid changes from point to point and spaces is called compressible flow. Incompressible flow: The flow in in which density of a fluid do not changes from point to point and spaces is called compressible flow. Newtonian flow: The flow in which shear stress of fluid is directly ptoportion

Bimetallic thermometers are made up of bimetallic strips formed by joining two different metals having different thermal expansion coefficients. The bimetal sensing element consists of a metal element shaped like a flat spring.  This element is two different metallic materials sandwiched together On heating of a strip the material,strip bends towards which having less thermal expansion coefficient.pointet is set at the end of the strip and which is moving on the angular or respective scale from which we can directly measure the temperature. eg.matrial like inver can be used consit of ferus and nikel joined with NI-MO alloy Advantages: 1)Low cost 2)Low maintaince Disadvantages: 1)Low responce and opearate at low temp due to creeping

Liquid in glass thermometer: In this instrument consist of a thick walled glass tube with a bore filled with a expanding fluid such as mecrury. The principle used to measure temperature is that of the thermal expansion of the liquid. Area of stem is less than the bulb when we deep the bulb of thermometer in a hot liquid the mercury or expanding fluid in the bulb expans and rises upward.linear scale is mounted on the stem.so directly we can measure the temperature. Advantages: 1)Good accuracy. 2)portable. Disadvantages: 1)limited range 2)More time consuming

Newtonian Fluid: The fluid in which Shear rate is directly proportional to shear strss is called newtonian fluid. generally air,water is known as newtonian fluid. Non newtonian Fluid: The fluid in which shear stress is not proportional to shear force is called non newtonian fluid. generally blood thick lubticating oil is known as non newtonian fluids.

Theory of Machine may be defined as that branch of Engineering-science, which deals with the study. Kinematics . It is that branch of Theory of Machine which deals with the relative motion between the various parts of the machines or assembly. Kinetics. It is that branch of Theory of Machine which deals with the inertia forces which is due to the effect of the mass and motion of the machine parts. Statics. It is that branch of Theory of Machine which deals with the forces and their effects when the machine parts are at rest. Dynamic . It is that branch of Theory of Machine which deals with the forces and their effects, when acting upon the machine parts in motion. Force      which may be defined as an factor which produces any activity or oppose to activity, complet activity or tends to complex activity. Resultant Force           If a number of forces A B C etc. are acting simultaneously on a particle, then a single force, which will produce the same effect as that of all the

Mass Density: It is the mass of the fluid per unit volume. It unit is kg per cubic meter. Specific Weight: It is the weight per unit volume of the fluid. It is the volume occupied by the unit mass of the fluid. Specific gravity: It is the ratio of specific weight of fluid to specific weight of stanfard fluid. Compressibility : Compressibility is the reciprocal of bulk modulus of rigidity. Kinematic viscosity: Kinematic viscosity is the ratio between Dynamic viscosity and density. Surface tension: Energy exerted on a surface of a liquid bye the downward force of the molecule is known as the Surface Tension. Capillarity : Capillarity is the phenomenon in which when we insert a small tube in a liquid vessel,the penomenon of rise or fall of a liquid level in tube is calles capillarity. capillary rise- dipped in water Capillary fall-dipped in mercury.

Ideal fluid:- The fluid which is imaginary and does not exist in practically or daily today life is called ideal fluid it can be assumed to be incompressible and inviscid. Real fluid:- AReal fluid which have a certain fluid propertiea are called as areal fluid. Real fluid exist in nature and not imaginary

The rotameter is used to measure the flowrate of liquids and gases. Therotameter consists of a, 1)tube 2) float. 3)inlet and outlet 4)scale principle: rotameter has a tapered tube withthe upper end larger than the lower end, having a float inside concentrically. The float moves up and downaccording to the flow rate, and the reading taken from.scale on tapered tube. working: as the flow Staring to inlet tube.according to the flow.,the float in the tapered tube goes on increaing or decreasing.float and liquid have gravity relations.as the flow increases float accelerate and as the flow reduces float decreases .so actual fliw rate can me measured by linear scale in taperes tube directly According to position of float Selection of rotameter is depend on various factors such as flow rate,scale.accuracy,cost.apllicatiin and cost and maintaince. Advantages: 1)Low pressure loss 2)Can measure very low flow rate 3)easy installation 4)variable viscous range Disadvantag

1)Venturimeter is the widely used device tomeasure the discharge through the pipe.  2)A venturimeter consist of a convergence ,divergence,and throat. 3)The principle of venturimeter is that when a fluid flows through the venturimeter, it accelerates in the convergent section and decelerates in thedivergent section, resulting in a drop in the staticpressure. 3) By measuring the difference inthe pressures at an axial station upstream of the convergent section and at the throat, thevolumetric flow rate can be estimated. 4)The flow through the venturimeter and hence through the pipe is given by Qactual = Actual discharge. Qth=theoratica discharge Cv =Discharge co-efficient. A1 =area at the inlet side  A2 =area at the throat side h =Differential pressure head dh=pressure difference  g =Acceleration due to gravity Applications:  chemicalship tankersgas stoves , Water aspirators,,Steam siphons Carburetors .The capillaries.

A pitot tube is used to determine the velocit y of a fluid flowing through a pipe Principle:pitot tube uses the principle based on bernoullies equation to measure the flow. Most pitot tube consist of two tubes.one measure the static pressure and the other higher pressure.low pressure tube measure static pressure and Higher pressure tube measuresure the the static pressure plus pressure required to stop flow. volumetric FlowFlow rate can be obtained using equation       Q=KAV K=flowflow coefgicient A=c/s area V=velocity of flowing fluid.

1)Strength: it is the ability of a material to oppose to the failure under the action of load 2)Elasticity: it is the property of a material in which body regain its original shape under removal of external force. 3)Stiffness: it is the resiatence to the elastic property. 4)plasticity: it is the property of a material by which body undegoes a permanant deformation under the action of force. 5)Malleability: it is the property of a material by which we can beaten material in to thin sheets.eg.copper, silver 6)Ductility: it is the property of a material by which we can draw a thin wires.eg.silver,brss 7)Brittleness: it is the ability of a material by which material undergoes a rupture without undergoes a deformation 8)Hardness: it is the pr

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Types of mechanical instruments 1)Active and passive instrument. The instrument which require external power for manipulation and measurement is generally known as a active instrument. eg.potentiometer. The instrument which does not require external power for manipulation and measurement is generally known as a Passive instrument. eg. Liquid level measurement using fload and gear arrangement 2)Analog and digital instrument: The analog instrument in which the output can have an infinite number of values within the range that the instrument is designed to measure.eg.voltmeter The analog instrument in which the output can have an finite number of values within the range that the instrument is designed to measure. eg .electronic speedmeter 3)Null type and deflection type instruments: In the deflection type instrument quantity being measure displayed in terms of the amount of Pointers deflection Eg.pressure gauge. In null type instrument measurement is done on

Characteristics of the instrument 1)static characteristics: Accuracy: is how close is the measurement to the true value.     Percentage error = (( indicated value – true value ) / true value )x 100% precision :it is a successive difference between the two reading. An instrument can  be precise but inaccurate. Range : The total range of values an instrument is capable of measuring. For a standard thermometer this is 0 to100 ° C. so range is 0-100 ° C Span :it is a algebraic difference between largest and smallest reading of the range. suppose thermometer operate between 0-100 Degree cl.then range=100-0=100 ° C Stability : Output is constant when the input is constant. Tolerance :is the maximum error. A1000kW resistor with a tolerance of ± 5% has an actual resistance between 950and 1050KW. Sensitivity :change of a output according to input.Overall sensitivity – a measurement system consists of a number of devices. If the sensitivities of these devices are

Errors in Measurement 1)Instrumental Errors These errors may be Occure due to wrong construction, calibration of the measuring instruments. These types of error may be arises due to friction ormay be due to hysteresis Reason: poor maintaince,faults in construction,friction wear,assembly error. 2)Environmental Errors: This type of error arises due to external natural condition effect on the instrument. reason: temperature pressure humidity magnetic field Remedial action: Maintain the natural quantity constant .all measurement should be taken in the well laboratory. 3)Observational Errors these types of error caused due to observers observation reasons: Parallax error wrong conversion of unit wrong scale reading personal bias to take higher or lower reading. 4)Theoretical . Due to simplification of the model system or approximations in the equations describing it. 5)Oper