HOW TO CRACK GATE EXAM....MECHANICAL

HELLO FRIENDS,

This year i wrote GATE exam for the first time and i secure 41.67 out of 100 and All India Rank is 4584 in Mechanical side.

Guys i want to tell you all that securing above 60 marks in GATE is not that much difficult. I was unable to get because of lack in preparation and not able to bear the pressure in the final 1 hour of GATE exam. still i got promising marks, that boost me up.

Well in mechanical from the last 3 or 4 years the GATE pattern was quite easy compared to that of 2007 and before. So now a  days some serious concentration on very important topics make you to get away with a very good rank.

Now i want to tell you that what are the most important topics in gate exam.

GATE PATTERN

GATE exam is of 100 marks and in mechanical average cut off is between 25 to 30, but may depend on the exam of particular year. there is 70 marks for the all technical part of mechanical side which consist of core mechanical subjects and other part consist of 15 marks engineering mathematics plus 15 marks for aptitude and English.

• Heat transfer, Thermodynamics, Fluid Mechanics and Machines, Strength of materials, Theory of Machines, Production Technology, Power plant, RAC and Machine Design, IC engines
• Engineering mathematics
• English and Reasoning and Aptitude

for me preparing time is less so i left machine design and RAC, but i suggest you to not to leave any of these subjects.i explain how to make this simple.

Strategy

• Firstly cover Thermodynamics completely with last 10 years gate papers and after that when you are through with the subject then its time for heat transfer and IC engine cycles i.e. Otto, and diesel cycles.
• With Thermodynamics it is easy for you to cover heat transfer and understand it easily.
• Now when you are done with these subjects then its time for Fluid and power plant subjects, comparatively fluid syllabus is more than power plant, power plant only includes vapour power cycle and steam power cycle. So these are the very important subjects
• Now the most important subject according to me is Production Technology, all last year exam gives you an idea how important is this. In GATE 2013 it consist of 16 marks out of 70. so it makes you feel that how important is this subject, so give sufficient time to this subject to justify its importance.
• In production technology metal cutting, casting, forming is very very important.
• Now subjects Theory of Machines and Strength of Materials have equal importance. Always 7 to 8 marks is expected from these subjects.
• Machine design and RAC consist of less marks but never underestimate these subjects as of their importance.

According to me at least 20 to 25 days are requires for the practise after your preparation of all subjects.

other subject i.e. maths, Eng. and aptitude also require time for the practise.

HOW TO MAKE PREPARATION SIMPLE

Now you are thinking all these subjects done at a time is very difficult to remember. so here the some ways to how to do this:

1. firstly you prepare thermal subjects i.e. Thermodynamics, heat transfer, IC engines.
2. then start fluid along with practise of previous subjects.
3. at the middle of fluid start production and
4. when fluid ends along with of production start some 1 or 2 hour practise of maths, and aptitude.
5. when you all are done then try to give some tests so that to increase your speed.
6. doing all your practise set a time alarm near to you so that every time you can increase your speed.
7. now for machine design and rac if more time is there then go completely through these subjects
8. but if time is not there then try to see last year papers what is they are asking in these subjects and make Strong that topics.
9. 20 to 25 days of complete practise is must.
10. try to maintain daily 8 to 10 hours, is you are able to give more that is up to you

soon i will post some more information regarding gate exam and list of important gate topics.
you can ask for any of your doubt.

keep preparing....



 

Pro e my first car in progress

hello friends ,
today i am going to share my first car design using pro e wildfire 4.0. i hope u will appriciate it.

Fluid Mechanics Basics

Hello friends,

today i am going to teach you some very basic concepts of fluid mechanics.
lets starts:

FLUID
we know in solids the molecules are very close to each to other, so they always show a fixed angular deformation as shown below

But In fluids this deformation which we generally describe as shear is not fixed, their we get continuous deformation beacause of the flow property. We term it as viscosity, later on i will explain the Viscosity. That's why here angular deformation keep on changing so here we get continuous deformation.

Gases and Liquids are having very important property of continous deformation which is termed as flow property.

So we put gases and liquids in different cateogry which is far away from solids and known as FLUIDS.

Fluid as Continuum:
                                  Continuum means continous mass. We have two types of studies of fluids one is microscopic and orther is macroscopic.

In Microscopic voids or the interstitial gap between the molecules can not be neglected. But in Macroscopic we can neglect the voids with respect to system dimensions.

so the fluid system can be treated as continous distribution of mass and this concept is known as continuum.

BASIC PROPERTIES OF FLUIDS

1. Density (ρ)
It is defined as the ratio of mass to the volume.

S.I units,
mass=kg
volume= m³
So density = kg/m³

2. specific weight (w)
It is deined as the ratio of weight to the volume of fluid.

3. Specific Gravity (S.G)
It is defined as the ratio of density of fluid with respect to standard fluid.

for liquids , water is taken as standard fluid and density of water is 1000 kg/m^3.
for gases , air is taken as standard and density of air is 1 kg/m³

4. Relative density:
 It is defined as the ratio of density of one fluid to the density of the other fluid.

The difference Between specific gravity and realtive density is that in specific gravity we took ratio w.r.t standrad fluid whereas in relative density no concept of standard fluid. It is a general ratio term.
If at any place like in examination if you found some term like this then examinar must clear by telling the other fluid also, if other fluid is not given then it is understood that specific gravity is given.

5. Compressibility (β)
This term basically defined as to check the change in volume of the fluid when pressure is changed.

this term is -ve because as pressure increases volume must decrease or vice versa. hence both are opposite so term is -ve, but we want to define compressibility as +ve so we multiply it with -ve to make is postive.

Now, we know mass is always conserved.
                                                                                    ρV= Constant
differnetiate this equation
                                                                                       ρdV + Vdρ = 0

put this value in abobe equation

Now, we define Incompressible Fluid
Actually density not change with respect to pressure

 These Fluids are termed as Incompressible fluid.

Liquids
 For liquids generally we take water it is compressible but very small change in volume with very high pressure increase.
so liquids can be treated as incompressible they are not actaully incompressible.
so mark this line i.e can be treated as.

Gases
From ideal gas equation we can see that pressure is directly prop to density.

so in gases density changes abruptly with change in pressure.so these are highly compressible.

6. Viscosity

"two adjacent layers of fluid resist the reltive motion of each other such a fundamental property is known as viscosity".

Basic cause:
The basic reason is cohesive forces which is acting between the molecules of the fluids.
they resist each other due to which friction develops or shear stresses develop, this is known as viscosity.

where

τ = shear stress

µ = viscosity

                       

                              Keep reading and keep exploring your ideas in the real world.

 

Basic Thermodyanamics Concepts

Reversible Process

 A process is said to be reversible process if when reverse leaves no effect on system and                 surroundings and follows the same path.

1.       Reversible process is the most efficient process and is used for comparing other actual processes.

2.       Reversible process is simple to analysis

3.       Friction is one of the cause which makes the process irreversible

 

Quasi-static Process
A process which is carried out in a very slow manner such that the difference in the pressure is negligible, such a beautiful process is called as quasi-static process

NOTE: A frictionless quasi-static process is reversible process.

A Report on AIR ENGINE COMPRESSER MODEL

hello friends,
today i am sharing the a project report of mine on air engine compressor model..
following is the link..

AIR ENGINE COMPRESSOR.

my car design in progress

this is my car deign using pro e wildfire 4.0....

car design by me

Hover Craft-Minor Project

Hello friends,
i am sharing the work that what i had done on my hovercraft.i wanna tell you how i proceed to make this and it costs only 9000 to 10000 rupees.
History of hovercraft and principal is easily available on the internet so i am not bothering about that.so how i work over it below is the details:-
Parts required:-

blower with the motor

Rubber coupling

• Blower- if you wanna make i very small hovercraft then the blower commercially used is suitable for you and available in the market at the cost of about 1000 rupees. But if you want to make a notable hovercraft as i did then you need a industrial blower .it is available in the prescribed shops. so friends i want to catch the attention of you all that this blower comes with the electric motor and which rotates it at a speed of 2800 r.p.m but if you want to show your work then drive it with the engine say bike engine (Bajaj pulsar150cc or Bajaj discover 135cc). these engines are quite powerful and i am using the discover bike engine. blower costs me 2000 rupees and the engine costs me 4000 rupees.here in the above picture you can see how my blower looks.please don't bring the motor with it. In blower their is a impeller whose work is to suck the air and release it with the pressure. shaft from the bike engine connects with this impeller and here i am using rubber coupling so to ensure that it stay stable as it rotates at a very high speed.don't connect the shaft coming from the gear box rather than connect it to the directly to the crankshaft and in neutral set this to top speed so when you starts the engine then it starts the blower and it does it work.
• Ply board: I am using a very strong ply because as the weight of the engine and the blower is quite large so it can break your ply that's why i am using a strong ply.Fix the blower at the one end and the engine at the center.i am using 4 feet in length and 3 feet in width.it costs me 1000 rupees.
• Skirt material- This is the most important part of the hovercraft because it have to bear the pressure,weight,wear and tear. so must be according to the condition. i am using nylon cloth because it is strong enough to suite my requirements.it costs me 600 rupees.
• pasting material-you may also need the pasting material so to paste the skirt material to the ply from the upper side to prevent the leakage of the air.and after pasting you may apply steel strips(must be light in weight) to the pasting portion so that it will stay their.
• Tools and other required material- In making of the hovercraft you require a number of the tools. i prefer my college workshop so if you also had that facility than its good otherwise go to some sort of auto repair shop.

this is the least requirement for the hovercraft.The procedure of the making hovercraft step by step is explained in my nest post and also the video explaining the steps.till then starts exploring your mind about the hovercraft.know more about it from the internet and the related books.

Throttling Process

hello friends,

Today i am going to explain the basic thermodynamics concept of throttling.

Throttling is a process in which the flow of fluid is restricted by closing the valve partially. Now imagine their are students in a class room and as the bell rungs they started moving out. Now if the door is opened partially then their will be clusters form by the students. Similarly in flow of fluid their is restriction to flow. now as students form clusters they pushing other students and in the same way fluid particles start rubbing with other molecules and as a result friction is their and as we all know friction is one of the biggest reason for any process to make it irreversible.

Hence it is clear that Throttling is irreversible.

EXAMPLES OF THROTTLING PROCESS
1. Flow through a partially opened valve as in IC engines
2. Flow through a very small opening e.g orifice.
3. Flow through a porous plug.

Characteristics of Throttling
1. No Work Transfer
Explanation:
As we know their is work transfer in turbines due to very large pressure difference. but in the case of throttling their is very low pressure differences so the work we get is very small and this work is lost in overcoming friction. so here we generally neglect the work transfer.

2. No Heat Transfer
Explanation:
Lets see it with a example... imagine you open the freeze and took out your water bottle and just within the fraction of seconds you put back that bottle, now what is the temperature difference between the two states of the water bottle, it is approx. zero. It means heat transfer needs some time , now what happened in throttling is that device length is very small and the fluid is always pushed ahead due to the bulk coming and due this their is not much time for the heat transfer. As we are considering the steady flow and bulk is not accumulated in the device so heat transfer is also neglected.

3. Irreversible Process

4. Isenthalpic Process
Explanation:
The word ISENTHALPIC means same Enthalpy.
look we apply steady flow energy equation:

now neglecting potential energy changes and
heat transfer(q) and work transfer (w) are zero as the characteristics of throttling..

equation becomes:

now what we generally seen that practically velocities values (c1 and c2 ) are very very small as compared to enthalpies values so c1 and c2 can be neglected and finally

hence the process is Isenthalpic.