Thermodynamics 2

Question 1

Turbomachine “Loss Coefficient” (Y)

Answer 1

Y = (P₀₁ - P₀₂)/P₀₁

Question 2

In SFEE, +ive Q is…

Answer 2

Heat IN

Question 3

In SFEE, +ive W is…

Answer 3

Work OUT

Question 4

Turbine Stage Work Equation

Answer 4

W_{dot 13}/m_dot = h₀₁ - h₀₃
- h₀ is stagnation enthalpy
- Stator does no work, only rotor stages

Question 5

Rotor torque (τ)

Answer 5

τ_{on rotor} = - mdot(r₃C_θ3 - r₂C_θ2)

Question 6

Turbine Work vs Tangential Speed

Answer 6

Wdot/mdot = U(C_θ2 - C_θ3)
- Assuming no change in mean radius
- Make sure to use -ve work for a compressor
- +ive work for a turbine

Question 7

Axial force on turbine blades

Answer 7

-F = mdot (C_a2 - C_a3) + (P2A2 - P3A3)

Question 8

Change in Sensible Enthalpy for a change of state

Answer 8

Δh_s = int(T1-T2)( C_p(T) )dT

Question 9

Total change in enthalpy during reaction

Answer 9

Δh = Δh_s + Δh_c

Question 10

Total enthalpy for species i

Answer 10

h_t,i = h_f,i⁰ + h_i(T) - h_i(T₀ = 25°C)

where each h is h-bar

Question 11

Internal energies for combustion in a closed system

Answer 11

u = u_f⁰ + ( u_T,p - u_25°C,atm)

where each u is u-bar

Question 12

Converting enthalpy to internal energy

Answer 12

u = h - Pv

u-bar = h-bar - MPv

Question 13

Standard Enthalpy of Reaction

Answer 13

(At 1atm & 25°C)

Δh₀ = ( sum_prods(n_doth) - sum_rctns(n_doth) ) / n_{dot, fuel}