- #1

jsh111

- 8

- 2

- TL;DR Summary
- I would like to design (hobbyist) a small heater with self powering blower based on gas turbine principles with a relatively low self sustain speed, and gas velocity based, rather than pressure based. The idea is to have heat and small power generation in disaster situations where biomass or combustible oils are available, but more refined fuels are not

-Gas turbines, as a general rule require very high rotational speeds (tens of thousands of rpm for small tabletop models) in order to reach a self sustaining speed. Gas turbines are also limited to efficiency based on the pressure ratio generated by the compressor.

-Question: What is the limiting factor that demands such high rotational speeds, and what can be done to lower the self sustain rotational speed such that it is more on par with something like a reciprocating engine? I suspect the answer is based on axial pressures intrinsically requiring high rotational speed to produce any kind of significant compression

-A simplified version of Bernoulli's equation establishes that the pressure and kinetic energy of a gas are interchangeable, and in an ideal system remain constant.

-Question: Therefore is it not possible to design a gas turbine where rather than compressing the air to high pressure, we take advantage of faster moving air instead, where heat applied causes the air to move even faster

OR, suppose we have a high flow, low pressure air mover. can we not simply employ a venturi tube arrangement to expand the air, and therefore increase the pressure

-Is there any prior work that focuses on lower speed gas turbines for relatively low amounts of input thermal energy I might study (I am thinking 5-10kw of input energy). The closest so far I have come are Brayton's piston engine designs which operate on the Brayton cycle, but are not gas turbines

-Question: What is the limiting factor that demands such high rotational speeds, and what can be done to lower the self sustain rotational speed such that it is more on par with something like a reciprocating engine? I suspect the answer is based on axial pressures intrinsically requiring high rotational speed to produce any kind of significant compression

-A simplified version of Bernoulli's equation establishes that the pressure and kinetic energy of a gas are interchangeable, and in an ideal system remain constant.

-Question: Therefore is it not possible to design a gas turbine where rather than compressing the air to high pressure, we take advantage of faster moving air instead, where heat applied causes the air to move even faster

OR, suppose we have a high flow, low pressure air mover. can we not simply employ a venturi tube arrangement to expand the air, and therefore increase the pressure

-Is there any prior work that focuses on lower speed gas turbines for relatively low amounts of input thermal energy I might study (I am thinking 5-10kw of input energy). The closest so far I have come are Brayton's piston engine designs which operate on the Brayton cycle, but are not gas turbines