ESE 2019 AIR 14 INTERVIEW Experience

NAME – GOURAV SINGH

BRANCH – MECHANICAL

UPSC ROLL NO – 0830759

DATE OF INTERVIEW – 26-SEPT-2019

CHAIRPERSON – SMITA NAGRAJAN MAM

CHAIRPERSON

1. You did your B tech from IIT Jodhpur in System branch. What is exactly system science?
Ans. Mam it is new branch introduce by IIT Jodhpur in 2011. It is a multidisciplinary approach by our college to provide an open platform to student where they can select which courses they want to read. Most of the courses are elective in nature with few compulsory courses.

2. So which platform you choose then?
Ans. Mam I mainly opted for mechanical courses

3. Okay tell me any 3 things which you learn from your college that shapes you technically or as a person.
Ans. Mam, first of all, I got from my college is good communication skills. When I compare myself from myself in 12th class, I have improved a lot. Now I at least able to speak in front of a group properly. (Mam – you mean confidence?). Yes mam you can say that, I’m more confident now. Second things is handling big projects. (Mam – like?). Mam during my college, I took part in a competition conducted by SAE India in which we have to design and manufacture a 4 wheeler ATV. This projects consist of around 25 members. So it was overall a huge projects and I learn how to deal with a big project and how to work as a team.
Mam – okay so it shapes you technically. And the 3rd one?
Me – mam………I make some good friends in the college…

4. Okay beta good. Now just forget you are an IES officer. As an engineer, which problem of society you want to choose and work for the solution of that problem.
Ans. Mam as I am from Rajasthan, I want to tell you about one problem in Rajasthan which is known as silicosis. Recently lots of cases have been seen in Sirohi district where people who work in stone carving, due to inhalation of the dust coming from it, silica particles go to their lungs and causes this problem.

Mam – so what you will do to solve it.
Me – mam we can use a machine which sucks that smoke (mam – machine like vacuum cleaner?).
Yes mam something like that with little modifications.

Mam – have you ever come across any machine like that?
Me – yes mam, in our college while doing welding we have a machine which sucks the smoke coming from the welding, so something like that can be used. (Mam – what is the cost of that machine). Mam I don’t know about the cost.

Mam - if something like that is available, what do you think, why they don’t use it. Is cost might be the factor?
Me – mam I don’t think so that cost is a factor. I thinks its lack of awareness and knowledge.

Mam – do you know about the present scenario?
Me – mam if I talk about the present situation, they don’t even wore the mask and gloves. They should focus on proper safety while working. And recently a man age just 40 dies because of silicosis. He is too young to die.

Mam – how do you know all these? Have you read about it somewhere?
Me – no mam, my teacher told me about this when I talk to him.
Mam – which teacher?
Me – mam he is from my college that is IIT Jodhpur professor.
Mam – so it was discussed during your college time?
Me – no mam, I discussed it with him after my graduation when I talk to him recently.

Mam – so beta, is there any jugaad we can use, India me to jugaad bohot chalta hai.
Me – yes mam chalta to hai. We can use a normal fan (mam – or something like blower?). Yes mam, something like that and put a duct around it.
Mam – acha to uski opening kaha rakhege , jaha kam ho raha hai uske pas?
Me – yes mam, close to the stone carving operation so it can suck the dust.
Mam – so do you think, will it work?
Me – mam at least it will reduce the smoke inhaling by them.

Mam – okay beta

TECHNICAL PERSON 1

There is a factory where couches as painted, there they have a 40 feet tall tower which suck the smoke and sends it to 40 feet above in atmosphere but still it can’t suck the Nano-sized particles. So blower might not work (he was giving some suggestions on that machine but initially I thought it was a question, later I realize it wasn’t)

1. Anyways do you know a place called merta? So for what merta is famous for?
Ans. Sir I don’t know anything specific in merta which is famous.
Sir – you know Mira Bai (me – yes sir) it was her home town. Then he told about some murti.

2. You took part in Baja only. Not Supra?
Ans. No sir

3. So you have done an interesting workshop which is on vehicle dynamics. Tell me some factor you will consider for designing a vehicle.
Ans. Sir, first of all, I start with transmission system, that how power from engine goes to the wheels.To reduce the rpm I will use a gearbox, if it is a rear-wheel drive, I will put differential on rear wheel so they can turn at a different speed.

Sir – okay but these are present in all vehicle. What type of shape you will use, that is
aerodynamically.
Me – sir we look at the aerodynamics of the vehicle if it runs at a higher speed to mainly reduce drag.

Sir – but I haven’t talk about speed. Okay let’s consider a racing car, now tell me the dynamics.
Me – sir for racing cars, as it is running at very high speed, they are designed in such a way that there drag will be minimum and get a lift force in a downward direction. They have both front and rear spoilers which gives them good tractive force.

Sir – so we keep their height small?
Me – yes sir we there CG lower.

Sir – so what type of tyre they use? Big small or what
Me – sir the tyre in which we provide our power is generally kept larger than non-driving tyre.

Sir – okay so what is the span you will use? (Me – sir we will prefer larger span). Larger okay, why we use it?
Me – sir as larger span gives good stability while turning……(I can’t able to explain it correctly)

4. It’s okay. So do you know about intercooler in turbocharging. Why it is provided in diesel in the engine?
Ans. Yes sir, the intercooler will cool down the air coming out from compressor.

Sir – why it is needed?
Me – sir I don’t know in diesel but in a petrol engine, it will reduce the temperature of intake air so that knocking tendency will be reduced.

Sir – okay, what is knocking?
Me – sir in petrol engines, the auto-ignition of the end charge which causes two different flame front to collide I term as knocking. It causes higher vibration and noise in the engine.

Sir – so tell me, if I have two fuel. One is neo heptane and one is octane. Which one is better?
Me – sir for a petrol engine or diesel?
Sir – let’s say petrol, have you heard about these names, neo heptane, octane, what is special about them?
Me – sir is it octane or iso-octane?
Sir – okay take iso-octane.
Me – yes sir, these two are the two reference points used for giving octane numb to the fuel.
Sir – so higher octane numb is good or what?
Me – sir higher the octane numb, lesser will be the knocking so it’s good
Sir- so octane numb is given to the fuel or the engine?
Me – sir engine
Sir- really? Then why we call a fuel have less knocking tendency?
Me – sorry sir, it is given to the fuel

5. So in petrol engine…..wait….you try to divert me from petrol to diesel. That was a good try. I almost forgot I started with diesel. Now I again come to the diesel.
Sir gave my different piston shape and fuel entry point and ask me what will be the effect on
combustion. Is it good or bad?
Me – sir the tangential entry of the air will give initial turbulence to the….

Sir – so is there any name for that turbulence?
Me – yes sir, it is squish

Sir – yes, you can use these terms if you know them. So this turbulence is good or bad.
Me – sir it is good as it creates a uniform air fuel mixture in the chamber. So there will not be any localize combustion.

Sir – what about this dome shape piston, will it also give the same uniform mixture.
Me – yes sir it will also help in creating better air-fuel mixture.

6. So what is stoichiometric ratio?
Ans. Sir it is the perfect AFR require for complete combustion

Sir – so what you called a mixture with more air than required?
Me – sir it is leaner mixture

Sir – now consider a slightly lean mixture, so it is bad or good?
Me – sir at slightly leaner mixture let’s say 0.95, NOx formation will be maximum.

Sir – what is 0.95? Are you dividing it with stochio or multiplying it?
Me – sir 0.95 that is when we divide our mixture to stochio

Sir – are you sure, isn’t is reverse?
Me – no sir its not. I’m sure.
Sir – so at 0.95, NOx CO and UBH will be max.
Me – no sir, only NOx
Sir – okay, so tell me stoichiometric ratio of diesel
Me – sir….may be around 14
Sir – no its 17….it’s okay

TECHNICAL MEMBER 2

1. So you were talking about span of vehicle will helps in turning. Can you explain?
Ans. Yes sir, more span will be good

Sir – don’t you think our vehicle will topple?
Me – no sir, if span is more, the centrifugal force acting on vehicle which gives a upward force on tyre, will be less than the downward force acting on them…

2. Okay so you just took part in baja….not efficycle?
Ans – yes sir, we manufacture both baja and efficycle.

Sir – so, not took part in any tech fest?
Me – no sir

Sir – so you just manufacture Baja and efficycle and not took part?
Me – ohh…yes sir we took part in both the events, but except that I didn’t take part in any tech fest

Sir – okay so where these events were held?
Me – sir Baja was in Indore and efficycle was in chandigarh
Sir – okay so you got any prize?
Me – no sir, our rank in efficycle was 31 and in Baja was 59.
Sir – who was the 1st ranker?
Me – sir in baja, 1st ranker was a college from Pune….. I am not able to recall its name right now.

3. Okay so you did a workshop on vehicle dynamics. What did they teach you and tell me about the workshop?
Ans. Sir the workshop held in our college itself where some experts took a lecture on different areas
Sir – how they teach you….from where they start like mechanism or force or what?
Me – sir they start with basics like traction force tyre and engine then they move towards different systems like braking, suspension, steering etc

4. So what was your role in Baja team
Ans. Sir I was mainly responsible for the braking system. In this we use a balancing bar mechanism for dividing the brake force in front and rear, though this mechanism available in market but we decided to manufacture it by our own due to higher cost.

Sir – which material do you use?
Me – sir in which part?
Sir – in your brake….what type of brake was it (me – disc brake)…..which system is used in cars (me –sir mostly we use disc brakes)….so tell me its material which you used? (He might think we manufacture the disc also)
Me – sir it was cast iron

Sir – do you think cast iron can take that much force (me - I am not sure sir)……in other vehicles, which material is used?
Me – sir it is mostly composites or cast iron

5. Okay so you told me you were responsible for steering system of baja also?
Ans. No sir…I was only handling the braking system.
Sir – do you have an idea of steering system also?
Me – yes sir
Sir – which type of steering is used in racing or F1 cars?
Me – sorry sir, I don’t know

TECHNICAL MEMBER 3

1. So while you were in aeromodelling. Do you learn any software or something
Ans. Yes sir. During starting I learned how to use SOLIDWORKS and design our aerofoil in it. Later on in college I learned basics of ANYSIS also but not in aerodynamics field, only basic stress analysis

2. So you were in aeromodelling….tell me how to design dome
Ans. Sorry sir….i don’t get it
Sir – dome….you don’t know…..front part
Me – of planes?
Sir – yes
Me – sir I am not sure about it
Sir – its okay….just think
Me – sir in dome we will try to design it in such a way that drag will be minimum
Sir – so which shape will give you that…..how will you minimize it?
Me – sir we will try to keep the frontal area as minimum as possible coz more frontal area will give more drag
( tech member 1 – you should tell me this also when I ask you about the aerodynamics of vehicle…..you knew it but didn’t tell)

3. You have seen different vehicle have different shape….some are aerodynamically very
good….some are not….what do you think?
Ans. Sir we will concerns about aerodynamics only when our vehicle is running at higher speed coz the power loss factor due to drag is 3rd power of velocity so higher the velocity…higher the power loss

4. So tell me what type of contact a tyre will have with the road? Is it line or circle or ellipse?
Ans. Sir it will be an uneven ellipse

Sir – uneven ellipse? What is it?
Me – sir I mean it will be more from one side and less form one

Sir – really? But the weight of the vehicle is equally distributed. Then why uneven?
Me – sir becoz of the viscoelastic nature of the tyre…there will be some residual strain in the
tyre….which causes the uneven contact of the tyre

Sir – residual strain or stress?
Me – no sir…its strain

Sir – okay so consider its x y and z-direction and our tyre is like this. Which direction will have more stress?
Me – sir it will be in y-direction

Sir – okay so now consider the inner and outer tyre….now tell me which will have more stress and strain?
Me – sir I don’t know
Sir – it's okay

CHAIRPERSON

1. So gaurav…these days there are lots of accidents in India. As an engineer, what will you do to reduce them? Is there should be any speed limits In every vehicle?
Ans. Mam in my opinion…yes there should be

Mam – so how will you do it….do you make switch for speed or what?
Me – mam there is a mechanism already available for that which is known as governing mechanism. It mainly available in public transport. Whenever the speed try to cross a certain limit, this mechanism starts and doesn’t allow the vehicle to cross that limit

Mam – so can you implement this in our vehicles?
Me – mam this mechanism is also available in taxi services like ola and uber…so if they can have it…other vehicle can also have it

Mam – do you think it's really possible?
Me – yes mam, it is

Mam – okay Gaurav…thank you

Tech member 1 – mam wait, I want to ask one more question. So you have seen something available in cars at the back called spoilers. What is their function?
Me – yes sir, they are of reverse aerofoil shape. I mean they have placed in upside down direction of plane wings. Their main function is to create a lift force in a downward direction which will increase the traction force and cancel the upward lift at higher speeds

Sir – so what about drag? Will it increase or decrease or what?
Me – sir about drag…….(I was thinking then sir told me its okay)

Mam – okay gaurav…thankyou…..aur sochna jrur ghar ja k iske bare me
Me – thank you, mam. Thank you, sir

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