Question

A liquid-propellant rocket engine is used to develop a thrust of 1.5 kN with a characteristic velocity of 1900 m/s at chamber pressure of 5 MPa. If its thrust coefficient CF happens to be 1.2, then the throat of nozzle is

• A. \(2.5 \times 10^{-4}\ \text{m}^2\)
• B. \(2.5 \times 10^{-3}\ \text{m}^2\)
• C. \(3.2 \times 10^{-4}\ \text{m}^2\)
• D. \(3.6 \times 10^{-4}\ \text{m}^2\)

Hint:

Throat area depends directly on thrust and inversely on pressure and thrust coefficient.

Answer 1

The Correct Option is A

Use the thrust equation: \[ F = C_F \cdot A_t \cdot p_c \] Solving for \(A_t\): \[ A_t = \frac{F}{C_F \cdot p_c} = \frac{1500}{1.2 \cdot 5 \times 10^6} = 2.5 \times 10^{-4}\ \text{m}^2 \]