Why dont jet engines work without a spiner in the center of the blades

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SUMMARY

Jet engines require a spinner at the center of the blades to function effectively in supersonic air due to the need for proper airflow management. The fixed center of the blades acts as an air dam, creating drag at subsonic speeds and significantly disrupting inlet performance at supersonic speeds due to shock waves. Inlet aerodynamics are crucial for high-speed flight, as demonstrated by the SR-71's J58 engine, where the inlet played a vital role in propulsion. Without a spinner, the engine face is left exposed, leading to performance issues.

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  • Understanding of jet engine mechanics
  • Knowledge of supersonic aerodynamics
  • Familiarity with airflow management techniques
  • Basic principles of shock wave behavior
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  • Study the design and function of the SR-71's J58 engine
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Just trying to complete my physics coursework on bloodhound ssc. Could anyone help to answer the question: why don't jet engines work in supersonic air without a spinner in the centre of the blades ?

Thanks.
 
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The problem is that the center of the blades is fixed, so it acts as an air dam. It is bad enough as a drag source at subsonic speeds, but when supersonic, the shock wave will play havoc with your inlet performance. So either the inlet slows the incoming air to subsonic and the engine face is left naked, as in the Tornado for instance, or the engine is part of the inlet and needs the spinner as part of the air flow management.
Inlet aerodynamics are a huge part of high speed flight. Read the discussions on the SR 71 and its J58 engine, the inlet did most of the work in propelling that airplane.
 

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