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Osiris
Personal Design Project
November 2023 - Present
Role: Project Lead
Organization: Personal Project
This project is in design and this page will be updated as progress is made.
Osiris was created to provide a challenge for myself (and others) to learn and establish a foundation in rocket propulsion. The goal of this project is to create open-source literature and software surrounding the design, manufacturing, and testing of a regeneratively cooled, pressure-fed, liquid rocket engine.
Engine Specs
- Engine Type: Pressure Fed Liquid Bi-Propellant
- Oxidizer: Nitrous Oxide
- Fuel: Ethanol
- OF Ratio: 1
-Thermal Management: Combustion Chamber Regen Channels and Film Cooling
-Mass Flow: 1 kg/s
-Expected Thrust: ~348lbf
The propellant was chosen based on our familiarity of working with both fluids, and their availability to acquire. Since it is our first iteration of an engine of any type, especially one with regen channels, a low OF was chosen to give the best chance at success. We hope to increase the OF in future iterations.
To streamline the initial process of propellant and OF ratio selection, I created a MATLAB application to graph and sort the results gathered from NASA CEA runs. NASA CEA (Chemical Equilibrium with Applications) provides critical design values used to create chamber geometry and other aspects of design. The MATLAB application reads in a CSV file of data (that the user previously formatted) then dynamically goes through and pulls out relevant information. This information is then sorted by both the chamber pressure and OF ratio that it was created with. Finally, the user can then plot different pressure cases and compare specific values. This allowed our team to quickly trade different OF ratios and chamber pressures during our initial design phase. Images from the application can be seen below:
Setup Page
Tabulated CEA data, sorted by OF ratio
Plotted data of different values based on the user selected pressure cases
Once the OF ratio and chamber pressure were selected, our team worked to create a general propulsion calculator. This took the form of an Excel spreadsheet, where initial and simple calculations are used to design further aspects of the system. Each sheet contained calculations and dimensions useful to a specific sub-system as seen below:
Fluid System
Major and Minor Head Loss
Minimum Diameter to Cause Choked Flow in Lines
Injector
Unlike Doublets Injector Type
Co-axial Injector Type
SolidMech
Preliminary Solid Mechanical Calculations for Pressure Surfaces
Regen
Rough Regen Channel and Heat Flux Calculations
These initial calculations allowed us to start a more detailed design using another MATLAB program I created and verification through RPA and Ansys simulations. RPA (Rocket Propulsion Analysis) was used to generate the chamber contour and validate CEA data. It also provided constants and properties used in the general propulsion Excel sheet. Finally, RPA was used to validate channel geometry calculated using the previously mentioned MATLAB program.
This MATLAB program reads in the chamber contour as a CSV file and creates arrays in both the radial and axial directions. It then differentiates along the length of the chamber, calculating and evaluating multiple variables at each differential length. The key objective of the program is to provide the Heat Flux and Heat transfer along each station in the chamber, and the total of those values. These are then used to evaluate the effectiveness of the regen channels to handle the generated Heat Flux. The program also dynamically sizes the dimensions of the regen channels using user-defined minimum dimensions, which are based on manufacturing constraints.
After calculating the Heat Flux and channel geometry, the pressure, temperature, and velocity of the propellant in the channels is calculated. An important metric is the final temperature of the propellant as it reaches the injector. The channels and mass flow must be designed to avoid letting the fuel reach its critical temperature. Fuel final temperature is a key metric to optimise for and is provided by the program.
Finally, all calculated vales are graphed and summarized by the program, allowing the user to quickly iterate through designs and evaluate the performance of such designs.
Results Plotted
Summarized Results
In our case, we used this program to initially size the channels and validate select values from our Excel calculator. We also compared our results to results from RPA and have been working to ensure they are similar. As of now, we are currently working to ensure that the Heat Flux matches with values from RPA, and will continue to verify the accuracy of the answers provided by the program. Once this is achieved, I plan to migrate this code into a MATLAB application and release it as an open source development tool.
All of these design tools allowed us to start on a preliminary CAD of the engine. Below are images of the latest iteration of the engine. I have started to move into injector design as the team works to finish finalizing and validating the channel geometry. A preliminary fluid system has also been created as we start to migrate upstream of the chamber.
Preliminary Engine Assembly
Preliminary Injector Face
Preliminary Unlike Doublet Injector
Cross Section of Engine Assembly
Preliminary Test Stand Configuration
Preliminary Fluids System P&ID
History of Current Designs for Fun
Next steps are:
- Continue optimizing the injector stack and fuel manifold.
- Size film cooling holes
- Refine and start Fluid System Design
- and lots of other things.......
All content is WIP and will be updated as we progress. If you have any questions or advice, feel free to reach out to me on LinkedIn :)
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