Assignment 4

Fig.4. Schematic diagram of the fuel system: 1 – reserve tank; 2 – transfer pump; 3 – throttle; 4 – filter; 5 – non-return valve; 6 – service tanks

Aircraft fuel system (Fig.4.) transfer pump of delivery Q supplies T-1 kerosene at the temperature 20 ⁰C to service tanks 6. The service tanks filling should be finished simultaneously.

The liquid head in the tanks should be omitted. Flight altitude H and other data are given in the table.

Determine:

1. Sucking pipeline diameter d₁.

2. Drive pump required power N_p.

3. Diameters d₃ and d₄ of the pipelines connected to the service tanks.

Solution technique:

1. Determine the main sucking line diameter using H, Q, P_en, h₁ and l₁ data(let l₁= h₁+0.6 m) and the standard one.

2. Find the drive pump required power according to P_p, η_usf, and Q data.

3. Determine pressure at point M, using Q, l₂, d₂, P_p data; then determine fuel feeding value to the service tanks, taking into account data of W₁, W₂, Q.

4. Calculate the required pressure head value for each diameter, using a number of pipeline diameters and plot the H_req= f (d) curve.

5. Determine the d₃ and d₄ pipeline diameters using available pressure head value, and choose the standard ones.

Note: Atmospheric pressure versus flight altitude curve is given in the Appendix.

Table 4