In attendance: Eric Hettinger, Brian O’Neel, Jim Ward
We discussed injector design. We believe that the design for the gaseous injector is not as terribly critical like it is on a liquid injector which must atomize the fluid. Our main concern is that the gaseous oxygen is diffused entering the combustion chamber so that none of it has sufficient velocity to pass through the central port without contacting the fuel and thereby leaving the combustion chamber unburned. We are not sure how much of an issue this is but we decided instead of just dumping the oxygen into the combustion chamber from the end of the feed hose we will have some form of 'injector nozzle' to fan out the oxygen.
Ideally we would like to have an off the shelf solution such as a pressure washer nozzle or oil burner nozzle with a solid or hollow cone pattern.
Originally we were going to limit our mass flow rate using the geometry of the orifice of the solenoid valve. After giving the problem some thought, it seemed like a better idea to use some form of flat plate metering orifice to control the flow. This way we can easily change the flow rate by changing out orifice sizes. This still needs to be looked into.
Placement of the O-rings was decided. There will be two 0.10" THK O-rings on the nozzle and one 0.10" THK O-ring seal on the injector side. They will be 2.00" and 2.75" OD respectively. Jim updated the drawing durning the meeting to reflect this
It was decided to add two more solenoids into the plumbing layout. They will be attached at the high pressure O2 and N2 tanks and will serve as emergency shut-offs in the event of the primary flow solenoids failing or a hose or connector rupture in the system.
We briefly discussed static test stand layout. We will be using the PSAS launch tower trailer for the test stand platform (with the tower removed of course) This will allow us a large degree of mobility and give us a greater selection of possible testing areas which have not been pinned down yet. The mobile test stand will also be used for the future liquid oxygen prototypes so we want to build as much cross-compatibility into the stand now as we can. It was decide that all components will be placed within fairly close proximity of each other, that is the oxygen tank and the combustion chamber will both reside on the trailer this will minimize plumbing and assembly for the tests. In the event of motor failure a stout barrier will be place in between the motor and the other components such as solenoids, tanks and data acquisition equipment.
There are still many things to do if we want to meet our goal of static firing a motor this summer but we are making good progress forward.
To Do List:
- Pressure vessel analysis
- Bolted connection analysis
- Weld analysis
- Nozzle design – Throat dia, exit dia., converging and diverging angles, O-ring placement
- Injector Design – Simple orifice, pintle, swirling, impinging doublet, (stainless steel or brass)?
- Research oxygen and nitrogen feed lines – Braided stainless steel? Look at different connectors and how they can adapt to the solenoid valves
Research injector design
Locate source for o-rings
Work on nozzle design
Practice, practice, practice TIG welding.
Update gox/paraffin motor drawing
- Acquire load cell and research appropriate pressure transducer
- Do preliminary drawing of static test stand
Need to add to website:
Lots of stuff :)