Post by britishrocket on Feb 27, 2012 9:57:43 GMT -5
Hello fellow amateur rocket developers. I am in the UK and I am attempting to build a bipropellant liquid rocket engine. I am using GOX and ethanol propellants. I'm looking at dump cooling with water initially, then regen cooling with the ethanol if possible. I may use a 70% ish ethanol water mix. I'm currently looking at injection schemes...coaxial shear and swirl. Check out my efforts at www.britishreactionresearch.blogspot.com
Post by britishrocket on Feb 27, 2012 14:54:49 GMT -5
Many thanks for making my post into a separate thread. I normally use my blog for archiving my progress. I would like to invite anyone who is interested in the construction of bipropellant rocket engines to view/join it.
Those of us who are building LPRE are few and far between. I believe myself to be the only one in the UK, though I'm waiting to be proved wrong! Forums like this allow us to share the knowledge we have gained.
Post by britishrocket on Feb 28, 2012 10:22:58 GMT -5
Hello Rocket developers. I have just posted two new articles on my blog, dealing with my research into injection systems. The first gives the design details for a practical test injector, based on my early research. The second describes the construction of this unit.
Post by britishrocket on Mar 12, 2012 14:05:59 GMT -5
I have just bought some K type thermocouples from a performance car parts dealer. They are intended for use as exhaust gas temp sensors. I'm going to use them as part of my engine project.
I'm looking at using the MAX6675 thermocouple - digital convertor IC to interface the units to either a BASIC Stamp or mbed microcontroller. The MAX6675 uses an SPI interface which I have plenty of experience with. Does anyone have any experience with the MAX6675? How does it fair? Be good to find out.
Post by britishrocket on Mar 13, 2012 12:44:34 GMT -5
Yes you are right if the thermocouples were exposed to the hot gases they would probably melt. It isn't the exhaust temperature I want to measure. The idea is to have the thermocouples buried in the injector and chamber flanges to try to get some idea of the hot gas side temperature and injector face temperature. This is to check the design of the injector. One of the claims of the coaxial type is that it gives a benign chamber environment, in other words relatively cool walls and cool injector face.
I'm also going to be measuring the coolant water outlet temperature and this along with a close approximation of the hot gas side wall temperature (from the thermocouples) will allow fairly accurate calculation of the heat transfer coefficients and heat fluxes. This will help with the design of future engines and show if it is possible to employ regen cooling with the fuel, and to what extent.
Thank you very much for your reply. I am very busy with work related matters at the moment, but as soon as I get a chance I will be posting more on injection. I have several videos of testing. I will post these and show modifications I made to improve performance. I also did a lot more research and I believe I have got closer to an understanding of the processes involved in coaxial injection. This research led me to consider swirl coaxial injection...another post to will detail this avenue of research, which is still ongoing.
Somewhere in there I will get my new workshop up and running...much bigger and insulated...I was working in my old one last winter in temperatures of -12 celsius and it was no fun at all!
Post by britishrocket on Mar 13, 2012 12:47:22 GMT -5
I forgot to mention in my last post that the thermocouples I have bought are for CAR exhaust gas measurement, as I said I'm not going to be using them for the rocket engine exhaust gas sensing. As you rightly say thats not really needed. Rather I am using them to measure the wall temperatures to check my calculations.
Post by britishrocket on Mar 28, 2012 2:04:28 GMT -5
Hi and thanks for your message. The engine isn't finished yet. On the blog I am essentially trying to play catch up by posting details of work carried out so far. In one of my early posts I mentioned that I intended to get readers up to speed as quickly as I could. I didn't expect it to take so long!
I have just moved house and so I need to get my new workshop up and running, which hopefully should be done in the next few months. The next few posts will detail the results of tests of the shear coaxial injector and steps I took to improve it. I will be posting video clips of it running. I have also done a lot of research into swirl coaxial injection and I will go on to describe this.
I am currently working on designs for a modular injector, that is to say a device that can be reconfigured easily to test different injection methods. I have also been looking at methods for increased heat transfer and more efficient cooling. So eventually this will be reported on as well.
Post by britishrocket on Mar 30, 2012 3:44:56 GMT -5
Hi, I'm pleased I cleared up any confusion. I said early on in the blog that it might not be the best medium for reporting on the engine project. I thought that because I am posting some pieces about work that is going on now, and some that happened up to two years ago. I long ago resigned myself to the fact that the project was going to take longer than I'd hoped!
The blog began as a way to keep friends and family informed with what was going on in the project. It has generated a lot more interest from the likes of yourself and others on this forum. I am really grateful for that and for the opportunity to share experiences with like minded people. I am learning a great deal from watching your progress.
Post by britishrocket on Mar 30, 2012 14:47:26 GMT -5
Hi and thanks for your question. I can't use LOX for various reasons, the main ones being:-
I cannot source/buy it legally in the United Kingdom I cannot store it legally on residential premises in the United Kingdom I have no facilities for storing cryogenics It is much easier to work with non cryogenics It is far safer to work with non cryogenics
I used to work with LOX and LN2 on a daily basis when I was an aircraft engineer. Unless an individual has received specific training in the handling and safe use of cryogenic substances I do NOT recommend their use. You can do yourself a SERIOUS injury with LOX and there is the potential for dangerously out of control fires and/or explosions. The type of thing that will not endear your rocket experiments to the authorities.
Check the post on my blog labelled "Fuel Concerns". It gives more details into the thought process I went through when deciding what fuels and oxidisers to use. I haven't yet ruled out Liquid Nitrous Oxide; it can be obtained legally and in safe containers designed for use in car performance enhancement. I decided on balance that GOX was the best option in terms of safety and availability, at least at first.
Sorry for the delay in replying to your earlier message. You are right that you need a "thermos" type arrangement for storing LOX long term You can store it very short term in a non insulated tank, as the "bulk effect" tends to slow down the boil off. I am talking about loading your LOX tank and then firing your engine literally minutes afterwards.
To reiterate, I do not recommend working with LOX unless you are familiar with and have been trained in the necessary precautions for handling it.