Hi Federico. Great question. Typically, turbomachery uses the damping ratio threshold value of 0.05 (same as log decrement of 0.3). But, for this rotor/bearing example, it requires more effective damping (>0.05) to successfully operate beyond the second critical speed.
Excellent inquiry! The rotation of the rotor induces fluid effects, such as contributing mass to the system. Liquid seals, for instance, result in significant direct stiffness and added mass (virtual mass) coefficients, causing a notable alteration in the natural frequencies (critical speeds) of a pump. Consequently, a differentiation exists between "dry" and "wet" critical speeds. In essence, virtual mass refers to the mass contribution originating from fluid inertia.
@@cck0728 Thanks! Glad you found it helpful. More content is on the way. If you have specific topics in mind, let me know. Also, please share these videos with your colleagues and engineering friends. Appreciate your support!
@@RotorDynamics Thanks... Just a query....Can you give examples for "wet seals"? I guess you mean, "water seal" seldom used in steam turbine for sealing steam? Please reply in your spare time... Thanks.
@@cck0728 A wet seal refers to a sealing mechanism designed to contain liquids, not limited to water, within a specific area. Seals play a crucial role in various applications, including liquid rocket engines.
Hi, thank you very much for the content. It's really practical and useful. I have been using free version of XLrotor, I am trying to recreate this model for validation, but free version doesn't allow more than 5 stages. Is it possible for you to share this file for educational purposes?
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Hello, would you be able to share the spreadsheet you used in your videos?
Thank you for the video. Based on your experience, for this rotor, which value of damping ratio could be acceptable?
Hi Federico. Great question. Typically, turbomachery uses the damping ratio threshold value of 0.05 (same as log decrement of 0.3). But, for this rotor/bearing example, it requires more effective damping (>0.05) to successfully operate beyond the second critical speed.
Good video.... What is "virtual mass"?
Thanks.
Excellent inquiry! The rotation of the rotor induces fluid effects, such as contributing mass to the system. Liquid seals, for instance, result in significant direct stiffness and added mass (virtual mass) coefficients, causing a notable alteration in the natural frequencies (critical speeds) of a pump. Consequently, a differentiation exists between "dry" and "wet" critical speeds. In essence, virtual mass refers to the mass contribution originating from fluid inertia.
@@RotorDynamics Thanks for such detailed explanation... Keep on posting...
@@cck0728 Thanks! Glad you found it helpful. More content is on the way. If you have specific topics in mind, let me know. Also, please share these videos with your colleagues and engineering friends. Appreciate your support!
@@RotorDynamics Thanks... Just a query....Can you give examples for "wet seals"? I guess you mean, "water seal" seldom used in steam turbine for sealing steam?
Please reply in your spare time...
Thanks.
@@cck0728 A wet seal refers to a sealing mechanism designed to contain liquids, not limited to water, within a specific area. Seals play a crucial role in various applications, including liquid rocket engines.
Hi, thank you very much for the content. It's really practical and useful. I have been using free version of XLrotor, I am trying to recreate this model for validation, but free version doesn't allow more than 5 stages. Is it possible for you to share this file for educational purposes?
Hello Jagdeep, can you help me use the free version? I have difficulties using the free version from XLrotor. Thanks.