A well-designed convergent-divergent inlet may allow nearly isentropic operation when the flight speed is at the...

Transcribed Image Text:

A well-designed convergent-divergent inlet may allow nearly isentropic operation when the flight speed is at the design Mach number. For preliminary sizing purpose, you can assume everything is ideal and may neglect other concerns (such as incorporating boundary layer growth or additional stability margins into the design). a. For such an inlet shown on the right, let's suppose that the inlet-to-throat area ratio is 1.45. I.e., A₁/At = 1.45. Then, what would be the design Mach number, MD, for this inlet? (show or explain your work) M> A₁ A A₁/A₁ = 1.45 b. If the inlet material structure is rather rigid so that A₁/A, is always held constant at 1.45, then at what Mach number will this inlet self start? In other words, estimate the flight Mach number, Moverspeed, at which the inlet shock can finally pass through the inlet duct throat? (show or explain your work) M>1 c. To start this inlet at a lower Mach number than Moverspeeds a bypass duct was designed which opens during the inlet starting process allowing some of the air flow to be removed from inside the duct. This active bleeding of airflow reduces the effective inlet area during the starting process and allows the shock to get "ingested" through the throat. Once the inlet is started, the bypass duct is closed and the inlet returns to the normal operation. A₁ A₁ i starting Now, the inlet starts when 18% of airflow entering the inlet duct is removed by the bypass duct. For this case, what is the new starting Mach number? In other words, if the effective inlet area could be reduced by 18% (A₁,starting = 0.82 A₁), at what Mach number would this inlet be able to start (i.e., ingest the shock)? A well-designed convergent-divergent inlet may allow nearly isentropic operation when the flight speed is at the design Mach number. For preliminary sizing purpose, you can assume everything is ideal and may neglect other concerns (such as incorporating boundary layer growth or additional stability margins into the design). a. For such an inlet shown on the right, let's suppose that the inlet-to-throat area ratio is 1.45. I.e., A₁/At = 1.45. Then, what would be the design Mach number, MD, for this inlet? (show or explain your work) M> A₁ A A₁/A₁ = 1.45 b. If the inlet material structure is rather rigid so that A₁/A, is always held constant at 1.45, then at what Mach number will this inlet self start? In other words, estimate the flight Mach number, Moverspeed, at which the inlet shock can finally pass through the inlet duct throat? (show or explain your work) M>1 c. To start this inlet at a lower Mach number than Moverspeeds a bypass duct was designed which opens during the inlet starting process allowing some of the air flow to be removed from inside the duct. This active bleeding of airflow reduces the effective inlet area during the starting process and allows the shock to get "ingested" through the throat. Once the inlet is started, the bypass duct is closed and the inlet returns to the normal operation. A₁ A₁ i starting Now, the inlet starts when 18% of airflow entering the inlet duct is removed by the bypass duct. For this case, what is the new starting Mach number? In other words, if the effective inlet area could be reduced by 18% (A₁,starting = 0.82 A₁), at what Mach number would this inlet be able to start (i.e., ingest the shock)?

Answer rating: 100% (QA)

a To find the design Mach number MD you can use the area ra... View the full answer