Adjusting the pressure drop in an injection plate

[Roy S Ramirez]

Hello everybody,

I'm designing a gas pressure feed system for a hydrogen peroxide - ethanol rocket engine, and after analyzing the devised injection plate, I noticed it is very sensitive to the propellants' pressure drops and discharge coefficients. Once the plate is manufactured, the only parameter I could adjust to get the correct flow would be the pressure drop (dP), which, as I mentioned, affects the engine's performance significantly with variations as low as 1 psi. How can I keep track of the actual dP's once I put everything together, and adjust the input pressure to achieve the desired dP's?
Roy S. Ramirez
AAE Sophomore - Purdue University

 

[Bystander]

This question implies that you've solved your previous question, https://www.physicsforums.com/threads/injector-pressure-drop-in-a-liquid-rocket-engine.951626/ ; and, you are aware of the peroxide hazards?

 

[berkeman]

Thread closed temporarily for Moderation...

 

[berkeman]

Hello everybody,

I'm designing a gas pressure feed system for a hydrogen peroxide - ethanol rocket engine, and after analyzing the devised injection plate, I noticed it is very sensitive to the propellants' pressure drops and discharge coefficients. Once the plate is manufactured, the only parameter I could adjust to get the correct flow would be the pressure drop (dP), which, as I mentioned, affects the engine's performance significantly with variations as low as 1 psi. How can I keep track of the actual dP's once I put everything together, and adjust the input pressure to achieve the desired dP's?
Roy S. Ramirez
AAE Sophomore - Purdue University

Hi Roy,

We need to make sure that you have the background to do this type of project safely (and we have to be careful not to allow threads about dangerous activities that other readers with less experience may then attempt themselves).

Please send me a message (click on my avatar and select Start a Conversation) with your background and a description of your previous projects. Also, do you have a mentor there with you helping you to work on this project, or are you all on your own? Where are you planning on storing these materials and doing the construction? Are you a member of your local rocketry club?

Here's your New Member Introduction Post:

Hello everybody, my name is Roy Ramirez. I'm an aerospace engineering sophomore at Purdue University, and my dream is to contribute to the globalization of space by developing more accessible space technologies.

 

[berkeman]

We need to make sure that you have the background to do this type of project safely (and we have to be careful not to allow threads about dangerous activities that other readers with less experience may then attempt themselves).

After a very nice private conversation with Roy, this thread is re-opened. Roy definitely has the background and qualifications to be working on this project at the university level, and he will mention safety issues and how he handles them in his posts (for the benefit of less experienced PF members and readers). Thanks Roy.

 

[JBA]

How can I keep track of the actual dP's once I put everything together, and adjust the input pressure to achieve the desired dP's?

It would appear from the discussion in your post that the critical issue is actually maintaining a constant discharge pressure; if this is true then referencing that pressure to the ideal design pressure, rather than the dP, should be the input to a controller that adjusts your input pressure accordingly.