3.3.39 · D1Hybrid engines — advantages, disadvantages
Ek core idea: ek hybrid rocket fuel ko solid block mein rakhta hai aur oxidiser ko flowing fluid ke roop mein, isliye aag sirf wahan hoti hai jahan flow surface ko touch karta hai — aur us flow pe ek valve on/off/throttle knob ban jaata hai.
Parent note mein jo kuch bhi hai (throttling, safety, "O/F shift", kam I s p
Isse pehle ki tum samjho kyun ek hybrid throttle karta hai ya drift karta hai, tumhe us alphabet mein fluent hona chahiye jo parent note quietly assume karta hai. Neeche, har symbol ko teen cheezein milti hain: plain words , picture , aur topic ko yeh kyun chahiye . Upar se neeche padho — har ek pichle wale pe lean karta hai.
Ek rocket ek tube hai jo mass ko peeche phenk ke aage badhta hai. Jis cheez ko woh phenkta hai use propellant kehte hain. Figure dekho: gas nozzle ke peeche se high speed pe nikalti hai (orange arrows), aur rocket aage ki taraf recoil karta hai (teal arrow).
Topic ko yeh kyun chahiye: hybrid ke har advantage/disadvantage ka matlab ultimately yahi hai — "kya yeh mass achi tarah, safely, aur controllably phenkta hai?" Toh humein un pieces ko naam dena hoga jo mass phenkti hain.
Ek rocket jo do ingredients jalaata hai woh hain:
Fuel — woh cheez jo jalna chahti hai (e.g. rubber, HTPB plastic). Campfire ke log ki picture lo.Oxidiser — woh cheez jo use jalne deti hai oxygen supply karke (e.g. liquid oxygen "LOX", nitrous oxide N₂O). Air ki picture lo jo hair-dryer log pe blow karta hai.
Aag = fuel + oxidiser + heat. Earth pe oxidiser free air hai; ek rocket wahan uda karta hai jahan hawa nahi hoti, isliye use apna khud ka oxidiser carry karna padta hai.
Question — Ek word mein, oxidiser kya supply karta hai jo fuel ko space mein jalne deta hai? Oxygen.
Phase = matter ki physical state: solid , liquid , ya gas .
Ek solid motor fuel+oxidiser ko ek hi solid grain mein pre-mix karta hai.
Ek liquid engine fuel aur oxidiser ko DO liquids ke roop mein rakhta hai.
Ek hybrid phases mix karta hai: solid fuel + fluid oxidiser .
Topic ko yeh kyun chahiye: poora chapter title hi "hybrid" hai, aur hybrid ka matlab hai alag phases . Agar tumhe "phase" ka matlab nahi pata, toh word khaali hai.
Phase ko socho jaise particles kitne ek-saath jaame hue hain . Solid = ek jagah locked (ek rubber block). Liquid/gas = flow karne ke liye free (pipe se beh ya spray karta hai). Ek hybrid locked wala fuel ke liye use karta hai (store karna safe hai) aur flowing wala oxidiser ke liye (valve karna aasaan hai).
Yeh parent note mein notation ka sabse important piece hai, aur wahan ise kabhi explain nahi kiya jaata. Hum abhi yeh theek karte hain.
Kisi letter ke upar ek dot ka matlab hai "woh quantity har second mein kitni tezi se change ho rahi hai" — ek rate .
m m ˙ mass flow rate = har second nikalte kilograms (kg/s).
Ek hose ki picture lo jo ek bucket bhar rahi hai. m bucket mein kitna paani hai . m ˙ bucket kitni tezi se bhar rahi hai — stream ki moti. Do alag ideas! Ek amount hai; ek change-ki-speed hai. Dot "amount" ko "amount per second" mein convert karta hai.
Topic ko yeh kyun chahiye: rocket ka push is baat pe depend nahi karta ki tumhare paas kitna fuel hai , balki is baat pe ki tum use kitni tezi se phenko . Isliye har thrust formula dots mein likha hota hai.
Question — m Ek rate: mass per second (kg/s).
v e exhaust velocity = nozzle exit se nikalte waqt gas ki speed (metres per second, m/s). Figure 1 mein orange arrows ki length socho: lamba arrow = tezi exhaust = zyada push.
Topic ko yeh kyun chahiye: push aata hai mass × speed phenkne se. Tumhe dono chahiye — "kitna per second" (m ˙ v e
Momentum term hi poori kahani hai: har second tum mass m ˙ v e F = m ˙ v e
Question — Thrust mein m ˙ m Kyunki force har second phenke gaye mass se aata hai, na ki tumhare paas total carry kiye gaye mass se.
ρ f fuel density = fuel ke har cubic metre mein kitne kilograms packed hain (kg/m³). Socho rubber grain ke muththi-bhar tukde ka bhari hona.A b burning surface area = solid wall ka woh area jo actively aag mein hai (m²). Hollow tube ki inner surface socho jahan aag wall ko chhoo rahi hai.
Topic ko yeh kyun chahiye: yeh jaanne ke liye ki har second wall se kitna fuel aata hai, tum teen cheezein multiply karte ho: wall har second kitna deep recede karta hai, kitne area pe, kis density par.
r ˙ regression rate = jis speed se burning wall fuel ke andar retreat karta hai, metres per second mein (m/s). Dot phir se gaur karo: yeh ek rate hai. Wall "regress" karta hai (peeche jaata hai) jaise fuel us se vapourise hota hai. Dekho Regression Rate and Boundary Layer Combustion .
Ek running tap ke neeche sabun ki batti socho: surface dheere dheere ghista hai, andar ki taraf jaata hai. Us andar ki retreat ki speed r ˙
Question — "Regression rate" ke liye kaun si picture match karti hai? Ek sabun ki batti tap ke neeche andar ki taraf ghisna — surface ke retreat karne ki speed .
A p or t port area = woh hollow central hole ka area jiske neeche oxidiser flow karta hai (m²). Jaise fuel jalta hai, yeh hole wider hota jaata hai.G o x oxidiser mass flux = oxidiser flow port ke har square metre mein kitna thunsa hua hai :
G o x = A p or t m ˙ o x (kg s − 1 m − 2 )
Flux = "flow kitna crowded hai?" Wahi m ˙ o x narrow hole se push karo = high flux (crowded, fast, hot). Ek wide hole se push karo = low flux (spread out, slow, cool). Yehi wajah hai ki O/F shift karta hai: jaise port wide hota hai, A p or t G o x m ˙ o x
Question — Jab m ˙ o x G o x Yeh girta hai — wahi flow ek bade area pe spread ho jaata hai, toh yeh kam crowded hota hai.
O/F = oxidiser-to-fuel ratio = m ˙ f u e l m ˙ o x ideal O/F hota hai. Isse duri propellant waste karta hai.I s p specific impulse = rocket ki "fuel economy" — har unit propellant use karne par kitna push milta hai. Zyada I s p Specific Impulse (Isp) .
Kyunki burn ke dauran A p or t m ˙ f u e l girta hai jabki m ˙ o x drift kar jaata hai. O/F ka drift karna hi wajah hai ki ek hybrid ka average I s p liquid engines se neeche aa jaata hai, chahe dono oxidiser ko alag rakhte hain. Yeh "O/F shift" signature hybrid disadvantage hai.
Ek green propellant woh hai jo non-toxic aur environmentally gentle ho (e.g. nitrous oxide, liquid oxygen) — un corrosive, poisonous liquids ke unlike jo bahut se rockets use karte hain. Kyunki ek hybrid ka oxidiser fuel se independently choose hota hai, ek green wala choose karna aasaan hai. Dekho Green Propellants .
Phases of matter: solid vs fluid
Hybrid = solid fuel + fluid oxidiser
Dot means per second: m-dot
Mass flow split: ox plus fuel
Thrust equals m-dot times v-e
Oxidiser is valved so it is throttleable
Fuel flow equals density times area times r-dot
Regression law r-dot equals a times G-ox to the n
Port widens so G-ox falls so O over F shifts
Hybrid advantages and disadvantages
Kya main words mein keh sakta hoon "phase of matter" ka matlab kya hai aur hybrid kyun hybrid kehlaata hai? Solid/liquid/gas state; hybrid = solid fuel + fluid oxidiser (mixed phases).
Kya main jaanta hoon kisi letter ke upar dot ka kya matlab hai? Ek rate — "har second mein kitna". m ˙
Kya main thrust equation likh aur padh sakta hoon? F = m ˙ v e + ( p e − p a ) A e F = m ˙ v e
Kya main jaanta hoon v e Exhaust velocity — woh speed jis par gas nozzle se nikalti hai (m/s).
Kya main m ˙ f u e l = ρ f A b r ˙ Density × burning area × wall-recede speed = fuel mass per second.
Kya main jaanta hoon r ˙ Burning wall andar ki taraf retreat karti hai — tap ke neeche sabun.
Kya main oxidiser flux G o x m ˙ o x / A p or t
Kya main regression law jaanta hoon aur n < 1 r ˙ = a G o x n n < 1
Kya main O/F aur I s p O/F = m ˙ o x / m ˙ f u e l I s p I s p
