AFCAT (Air Force Common Admission Test) EKT - Mechanical and Aeronautical Stream Syllabus

EKT - Mechanical and Aeronautical Stream syllabus — full chapter and topic list

Expand any chapter to see its topics and sub-topics. This is the whole examinable outline for EKT - Mechanical and Aeronautical Stream in AFCAT (Air Force Common Admission Test), not a summary of it.

1. 1

   Thermodynamics and Propulsion

   4 topics

   • Laws of thermodynamics
   • Thermodynamic cycles
     • Otto, Diesel and Brayton cycles
   • Gas turbines and jet propulsion
     • Turbojet, turbofan and turboprop engines
   • Heat transfer fundamentals
2. 2

   Fluid Mechanics and Aerodynamics

   3 topics

   • Fluid statics and dynamics
     • Bernoulli's equation and continuity
   • Aerodynamic forces and airfoils
     • Lift, drag and boundary layer
   • Compressible flow and shock waves
3. 3

   Theory of Machines and Strength of Materials

   4 topics

   • Stress, strain and elastic constants
   • Bending, shear and torsion
   • Kinematics of mechanisms
   • Vibrations and balancing
4. 4

   Flight Mechanics and Aircraft Structures

   3 topics

   • Aircraft performance and stability
   • Aircraft structural components
   • Manufacturing and machine design basics

EKT - Mechanical and Aeronautical Stream flashcards for AFCAT (Air Force Common Admission Test)

21 of 60 cards from the EKT - Mechanical and Aeronautical Stream deck — real questions with worked answers.

1. State the Zeroth Law of Thermodynamics.

   If two systems are each in thermal equilibrium with a third system, then they are in thermal equilibrium with each other. This law forms the basis of temperature measurement.

2. State the First Law of Thermodynamics for a closed system (cyclic and non-cyclic forms).

   For a cycle: the net heat transfer equals the net work transfer (cyclic integral of dQ = cyclic integral of dW). For a process: dQ = dU + dW (heat added equals change in internal energy plus work done). It expresses conservation of energy.

3. State the Second Law of Thermodynamics (Kelvin-Planck and Clausius statements).

   Kelvin-Planck: No engine can produce net work in a cycle while exchanging heat with a single reservoir (100% conversion of heat to work is impossible). Clausius: Heat cannot spontaneously flow from a colder to a hotter body without external work.

4. State the Third Law of Thermodynamics.

   The entropy of a perfect crystalline substance approaches zero as the absolute temperature approaches absolute zero (0 K). It is impossible to reach absolute zero in a finite number of steps.

5. What is the Carnot cycle and its thermal efficiency?

   A reversible cycle of two isothermal and two adiabatic (isentropic) processes. Its efficiency is the maximum possible: eta = 1 - T_cold/T_hot, with temperatures in Kelvin.

6. Describe the four processes of the Otto cycle and state its efficiency.

   Otto cycle (petrol/SI engine): isentropic compression, constant-volume heat addition, isentropic expansion, constant-volume heat rejection. Efficiency eta = 1 - 1/r^(gamma-1), where r is compression ratio.

7. Describe the Diesel cycle and how its heat addition differs from the Otto cycle.

   Diesel cycle (CI engine): isentropic compression, constant-PRESSURE heat addition, isentropic expansion, constant-volume heat rejection. Unlike Otto, heat is added at constant pressure rather than constant volume.

8. What is the Brayton (Joule) cycle and where is it used?

   The ideal cycle for gas turbines: isentropic compression, constant-pressure heat addition, isentropic expansion, constant-pressure heat rejection. Efficiency eta = 1 - 1/(r_p)^((gamma-1)/gamma), where r_p is the pressure ratio.

9. What is the Rankine cycle?

   The ideal vapour power cycle for steam plants: isentropic pumping of liquid, constant-pressure heat addition in boiler, isentropic expansion in turbine, constant-pressure heat rejection in condenser.

10. Define the Clausius inequality.

    For any cyclic process, the cyclic integral of dQ/T is less than or equal to zero. It equals zero for a reversible cycle and is negative for an irreversible cycle.

11. How does a turbojet engine produce thrust?

    Air is taken in, compressed, mixed with fuel and burned in the combustor; hot gases expand through a turbine (driving the compressor) and accelerate out the nozzle. Thrust comes from the high-velocity exhaust (Newton's third law).

12. Give the basic thrust equation for a jet engine.

    Thrust F = m_dot_air * (V_exit - V_inlet) + (p_exit - p_ambient) * A_exit. The first term is momentum thrust; the second is pressure thrust.

13. Compare turbojet, turbofan and turboprop engines.

    Turbojet: all thrust from core jet, best at high speed. Turbofan: a large fan provides bypass air for most thrust, efficient and quiet at subsonic/transonic speeds. Turboprop: turbine drives a propeller, most efficient at low speed/altitude.

14. Define propulsive efficiency of a jet engine.

    The ratio of thrust power (useful propulsive work) to the rate of kinetic energy added to the air. eta_p = 2V/(V_exit + V), where V is flight speed and V_exit is exhaust speed; it rises as exhaust speed approaches flight speed.

15. What is an afterburner and what is its effect?

    A device that injects and burns extra fuel in the exhaust downstream of the turbine, raising exhaust temperature and velocity to boost thrust substantially, at the cost of greatly increased fuel consumption.

16. State Fourier's law of heat conduction.

    Q = -k * A * (dT/dx). Heat conduction rate is proportional to the thermal conductivity k, area A, and the temperature gradient, with the negative sign indicating heat flows from hot to cold.

17. State Newton's law of cooling for convection.

    Q = h * A * (T_surface - T_fluid), where h is the convective heat transfer coefficient, A is the surface area, and (T_s - T_f) is the temperature difference between surface and fluid.

18. State the Stefan-Boltzmann law of radiation.

    The radiant emissive power of a blackbody is E = sigma * T^4, where sigma = 5.67e-8 W/m^2K^4 and T is absolute temperature. For a real surface, E = epsilon * sigma * T^4 (epsilon = emissivity).

19. Define the three dimensionless numbers: Reynolds, Nusselt, and Prandtl.

    Reynolds (Re = rho*V*L/mu): ratio of inertial to viscous forces. Nusselt (Nu = h*L/k): ratio of convective to conductive heat transfer. Prandtl (Pr = mu*Cp/k): ratio of momentum diffusivity to thermal diffusivity.

20. Define thermal conductivity and give its SI unit.

    Thermal conductivity (k) is a material property measuring its ability to conduct heat; it is the heat flow rate per unit area per unit temperature gradient. SI unit: W/(m.K).

21. State Pascal's law of fluid statics.

    Pressure applied to a confined fluid is transmitted equally and undiminished in all directions throughout the fluid. It is the basis of hydraulic systems.

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