Search found 23 matches

by russkey
Wed Nov 30, 2011 2:24 am
Forum: Technical - Engines and Boilers
Topic: Tverskoy-Pasechnik Rotary Steam Engine
Replies: 14
Views: 18388

Re: Tverskoy-Pasechnik Rotary Steam Engine

RogerV, the interlocking rotary engine you are referring to is indeed in interesting design. The original Tverskoy documentation actually states that it can also double as a pump. He designed it for battleship use. His thought was that you could have a set of these engines all attached to a single a...
by russkey
Sat Nov 05, 2011 2:22 am
Forum: Technical - non Engines and Boilers
Topic: Coefficient of linear thermal expansion
Replies: 2
Views: 6514

Coefficient of linear thermal expansion

My old physics textbook states that thermal expansion is is directly proportional to the change in temperature for relatively small changes in temperature (less than 100C˚ or so). It also hints that the coefficient depends somewhat on the temperature. It does not, however give any details of the non...
by russkey
Tue Nov 01, 2011 7:58 pm
Forum: Technical - Engines and Boilers
Topic: Mean Effective Pressure calculations
Replies: 8
Views: 11723

Re: Mean Effective Pressure calculations

AHA! There's the confirmation I was hoping for. I've juggled the equations a bit (updated the pdf: http://russkey.tumblr.com/post/12141995522/mep ) (and removed the illogical +P_b term in Eq. 5 and on) and came up with a formulation that only depends on the input pressure, back pressure, and the rat...
by russkey
Mon Oct 31, 2011 9:52 pm
Forum: Technical - Engines and Boilers
Topic: Mean Effective Pressure calculations
Replies: 8
Views: 11723

Re: Mean Effective Pressure calculations

I think the relationship you're using for expansion of steam is wrong for adiabatic expansion. Bart: You are correct. I'm assuming isothermal expansion, which is the relationship I've found in two books so far (at least for the initial rough estimates at the very theoretical level). fredrosse: This...
by russkey
Mon Oct 31, 2011 1:21 am
Forum: Technical - Engines and Boilers
Topic: Mean Effective Pressure calculations
Replies: 8
Views: 11723

Mean Effective Pressure calculations

Hello all,

I've put together this calculation of Mean Effective Pressure. I couldn't find this sort of estimation in the Steam Engine Design book by Lindsay Publications. I would love to get a second opinion on the math, though.

Any comments?

http://russkey.tumblr.com/post/12141995522/mep
by russkey
Fri Oct 21, 2011 2:52 pm
Forum: Technical - Engines and Boilers
Topic: Suitable Boiler for a LocoMobile Twin Simple (6hp)
Replies: 23
Views: 29048

Re: Suitable Boiler for a LocoMobile Twin Simple (6hp)

... how do you know what RPMs you should be turning ? ... Based on the things I've seen on this forum, as well as my reading of Steam-Engine Design, it seems that the only really practical way is to estimate and interpolate the RPM based on existing data on documented engines of similar configurati...
by russkey
Mon Oct 10, 2011 6:01 pm
Forum: Technical - Engines and Boilers
Topic: Tverskoy-Pasechnik Rotary Steam Engine
Replies: 14
Views: 18388

Re: Tverskoy-Pasechnik Rotary Steam Engine

Please forgive the possible blasphemy, but has anybody tried using a electronic valve timing mechanism? Something based on solenoid valves would be quite quick. A simple microcontroller would handle the input from a rotary encoder of some sort and the output to the valves. You could even use some of...
by russkey
Fri Oct 07, 2011 12:00 am
Forum: Technical - Engines and Boilers
Topic: steel cylinder?
Replies: 23
Views: 31796

Re: steel cylinder?

What kind of lighter and stronger materials do you have in mind? Perhaps not lighter and stronger, but easier to work with. I've always thought that cast iron was rather hard to machine due to some sort of crumbly nature. But perhaps that is just some silly thing I've picked up. Do the castings tha...
by russkey
Thu Oct 06, 2011 12:46 pm
Forum: Technical - Engines and Boilers
Topic: steel cylinder?
Replies: 23
Views: 31796

Re: steel cylinder?

...I believe cast iron is the material for cylinders and always will be...
This is actually something that has puzzled me for some time. Why *do* people still use cast iron? Why not lighter, stronger materials? Is it some sort of heat transfer concern?

Al
by russkey
Tue Oct 04, 2011 2:11 am
Forum: Technical - Engines and Boilers
Topic: Tverskoy-Pasechnik Rotary Steam Engine
Replies: 14
Views: 18388

Re: Tverskoy-Pasechnik Rotary Steam Engine

I presume that there was a time when even 50 micron machining accuracy was not possible, engines had to make do with some sort of tolerances and gaps between the cylinder and piston. Are there guidelines for an acceptable measure of seal imperfection? I would imagine that it might depend on the pres...