MCQOPTIONS
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MCQOPTIONS
This section includes 12 Mcqs, each offering curated multiple-choice questions to sharpen your Aerodynamics knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Select the flow which is not laminar all over the thin airfoil at α=0°.The given values are for Rec. |
| A. | 7×105 |
| B. | 9×104 |
| C. | 2×103 |
| D. | We can’t say with just this information |
| Answer» B. 9×104 | |
| 2. |
The laminar boundary layer for a thin airfoil is maximum at_____ |
| A. | Leading edge |
| B. | Trailing edge |
| C. | Quarter-chord |
| D. | We can’t say without calculating |
| Answer» C. Quarter-chord | |
| 3. |
We can get the skin-friction drag coefficient for a laminar flow for a flat plate by using x as chord length in local skin- friction drag coefficient calculation. |
| A. | True |
| B. | False |
| Answer» C. | |
| 4. |
The total skin-friction drag coefficient for laminar flow with Reynolds number at the trailing edge being Rec=40000 and chord length is 1m, is _____ |
| A. | 0.01328 |
| B. | 0.00664 |
| C. | 0.02656 |
| D. | 0.664 |
| Answer» B. 0.00664 | |
| 5. |
The constant which is present while establishing a relationship for Cf and Rec for a laminar flow is_____ |
| A. | 2.65 |
| B. | 0.664 |
| C. | π |
| D. | 1.33 |
| Answer» E. | |
| 6. |
The coefficient of skin-friction drag coefficient Cf, as conventionally defined, when used gives half the value of total drag. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 7. |
For finding the skin- friction drag we need to only measure shear-stress at the top or bottom surface. |
| A. | Always true |
| B. | Always false |
| C. | True for flat plate, which is a symmetric airfoil |
| D. | Depends on the Reynolds number |
| Answer» D. Depends on the Reynolds number | |
| 8. |
The boundary layer thickness for an incompressible, laminar flow at a distance x with Reynolds number Rex is δ. Which is____ |
| A. | Directly proportional to √x |
| B. | Inversely proportional to x |
| C. | Directly proportional to Rex |
| D. | Inversely proportional to Rex2 |
| Answer» B. Inversely proportional to x | |
| 9. |
For a Reynolds number Rec=9×104 and chord length 1m, what is the laminar boundary layer thickness at the trailing edge (in cm)? |
| A. | 2.34 |
| B. | 3 |
| C. | 1.5 |
| D. | 1.67 |
| Answer» E. | |
| 10. |
The Reynolds number for a fluid with density d, free-stream velocity V, viscosity u at a distance x from the leading edge is_____ |
| A. | R = \(\frac {Vd}{ux}\) |
| B. | R = \(\frac {xVd}{u}\) |
| C. | R = \(\frac {Vx}{dx}\) |
| D. | R = \(\frac {xdu}{V}\) |
| Answer» C. R = \(\frac {Vx}{dx}\) | |
| 11. |
The essential assumption of airfoil being a flat plate with a zero angle of attack gives accurate results always. |
| A. | False |
| B. | True |
| Answer» B. True | |
| 12. |
The defining assumption for finding the skin- friction drag on an airfoil is____ |
| A. | Airfoil is new low-speed airfoil |
| B. | Skin- friction acts due to shear force |
| C. | Airfoil has a zero angle of attack |
| D. | Airfoil is considered a flat plate at zero angle of attack |
| Answer» E. | |