**3.1 Orthogonal experimental design and results analysis**

### **3.1.1 Orthogonal experimental design**

An orthogonal experimental with four factors and three levels was conducted by keeping the main body size of the vehicle as constant. The four factors are wing chord, aspect ratio, backswept and distance between the center of wing root and the center of body. The simulation experiments were done at the situation of angle of attack is 6 α = ° and the velocity is *v ms* = 0.5 / . The airfoil of the wings was NACA0010. The orthogonal experimental table was shown as table 4.

Hydrodynamic Characteristics of the Main Parts of a Hybrid-Driven Underwater Glider PETREL 45

chord(mm) aspect ratio backswept (°) distance(mm) *L D*/ *l*

1 100 6 20 100 2.86 0.0274 2 100 8 40 0 3.11 -0.0323 3 100 10 60 -100 2.74 -0.109 4 150 6 20 0 4.07 -0.00059 5 150 8 40 -100 4.37 -0.0854 6 150 10 60 100 3.82 -0.127 7 200 6 40 100 4.88 -0.0158 8 200 8 60 0 4.47 -0.172 9 200 10 20 -100 6.81 -0.0713 10 100 6 60 -100 2.33 -0.0630 11 100 8 20 100 3.31 0.0212 12 100 10 40 0 3.44 -0.0444 13 150 6 40 -100 3.78 -0.0594 14 150 8 60 100 3.40 -0.0858 15 150 10 20 0 5.30 -0.0237 16 200 6 60 0 3.94 -0.115 17 200 8 20 -100 6.17 -0.0562 18 200 10 40 100 6.21 -0.0756

chord (mm) aspect ratio backswept location (mm)

Table 5. Orthogonal experimental table and the results

Fig. 6. L/D tendency chart

factors results

α

′

Simulation times


Table 4. Orthogonal experimental table
