Quiz 4

• What is the final flow deflection angle?

  theta_c
• In NACA 1135, which chart gives the variation of shock-wave angle, the surface pressure coefficient, and the surface Mach number vs cone semi-vertex angle? (In that order)

  Charts 5, 6, 7.
• Are the streamlines in the conical flow region curved or straight?

  curved
• Is the flow between the shock and the cone isentropic?

  Yes
• Is M_drag-divergence the beginning of the transonic flow regime?

  No, since usually M_dd is greater than or close to M_cr.
• Define M_cr?

  When the free-stream Mach number at which sonic flow is first encountered on the airfoil.
• What is an appropriate value for M_crit, as seen in PS12?

  0.8
• The best M_crit value we obtained was from the

  Karman-Tsien Rule (A compressibility correction).
• For a commercial jet, is it good idea to fly above M_drag-divergence.

  No
• According to Prandtl-Glauert Rule, compressibility will

  increase the magnitude of the lift coefficient and moment coefficient at the same AOA. Good up to M = 0.7.
• Of the three methods we studied, the most accurate is the

  Karmen-Tsien rule
• Is the Laitone's rule based on nonlinear analysis?

  Yes, so does Karmen-Tsien rule.
• Thin wings and slender bodies produce

  small disturbances in the flow field
• A thick wing at AOA produces

  larger disturbances in the flow field
• For thin wings and slender bodies, can we linearize subsonic flows?

  Yes
• For thin wings and slender bodies can we linearize transonic flows?

  No
• Give the linearized Cp in terms of perturbation velocity (ies)

  $C_p =$$-2u'/V_∞$
• In order for velocity potential to exist, flow must be

  Irrotational
• For all adiabatic flow,

  total enthalpy is constant
• Transonic and hypersonic flow can't be

  linearized
• Is conical flow obtained by Taylor-Maccoll considered to be exact?

  Yes
• Does the conical flow theory provide the pressure coefficient or the temperature on the cone?

  The pressure coefficient
• Is it possible to have a bow shock wave in front of a sharp cone?

  Yes, when the shock wave becomes detached when θc > θc_max
• M_cr for a thin airfoil is [BLANK] than that for a thicker airfoil at the same AOA

  greater
• For a given airfoil, M_cr will [BLANK] with increasing positive AOA

  decrease
• Is M_cr lower than the M_drag-divergence?

  Yes
• The quickest M_cr value we obtained was from the

  Prandtl-Glauert Rule
• Of the three methods of linearized flow methods, the least accurate is the

  Prandtl-Glauert rule
• Is the Karman-Tsien Rule based on linearized analysis?

  No
• Name the equation that the "Velocity Potential Equation" reduces for the case of linearized subsonic flow.

  Prandtl-Glauert
• When we linearize a problem, we neglect the

  nonlinear terms
• Is there upstream influence in supersonic or subsonic flow if one were to scream into the flow regimes, can the person upstream hear you?

  subsonic flow only.
• Which can be turned away from itself to a greater degree, without flow separation, subsonic or supersonic?

  Supersonic
• For small flow deflection angles θ, the non-dimensional pressure rise across the shock is proportional to what power of θ?

  1
• For small deflection angles, θ, the entropy rise across the shock is proportional to what power of θ?

  3
• Is conical flow solution obtained from Taylor-Maccoll equation a numerical solution or an analytic one?

  Numerical solution
• Is the pressure coefficient on the cone, C_pc variable or constant?

  constant
• In NACA 1135, is Chart 4 for conical flow or 2-D oblique planar shock?

  2-D oblique planar shock
• Is the flow in the conical flow region undergoing compression or expansion?

  Compression
• Is it a good idea to cruise at M = 1?

  No