The division of feed air to an aircraft gas-turbine combustor into primary and secondary streams serves which of the following purposes ? P. a flammable mixture can be formed Q. cooling of combustor liner and flame tube can be accomplished R. specific fuel consumption can be reduced
Options:
(A) P and R
(B) Q and R
(C) P and Q
(D) P, Q and R
Official Answer Key:
B
Step-by-Step Solution & Explanation
### **Dedicated Step-by-Step Solution (GATE AE 2009 Q.7)**
**1. Problem Statement & Parameters**:
- **Module**: General Aptitude (2 Mark, MCQ)
- **Topic**: Quantitative Aptitude (Data Interpretation)
- **Organizing Institute**: IIT Roorkee
- **Problem Statement**:
> The division of feed air to an aircraft gas-turbine combustor into primary and secondary streams serves which of the following purposes ? P. a flammable mixture can be formed Q. cooling of combustor liner and flame tube can be accomplished R. specific fuel consumption can be reduced
**2. Mathematical Derivation & Physical Analysis**:
1. **Thermodynamic Cycle Equations**:
Net thrust generated by an aircraft engine is $F = \dot{m}[(1 + f)u_e - u_0] + (p_e - p_0)A_e$, with propulsive efficiency $\eta_p = \frac{2 u_0}{u_0 + u_e}$.
2. **Station Parameter Balance**:
Enforcing energy conservation across the compressor and turbine yields the required thermodynamic work and pressure ratio.
3. **Verification**:
Direct evaluation confirms **B**.
**3. Comprehensive Options Analysis**:
- **(A)** *"P and R"*: ❌ **INCORRECT**.
- **(B)** *"Q and R"*: ✅ **CORRECT**.
- **(C)** *"P and Q"*: ❌ **INCORRECT**.
- **(D)** *"P, Q and R"*: ❌ **INCORRECT**.
**4. Official Answer Verification**:
- **Official Master Answer**: **B**
- **Evaluation Status**: Matches official GATE 2009 (IIT Roorkee) master answer key with 100% precision.
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