When dealing with students at different stages of thermodynamics and aerodynamics education, most early students ask about the different profiles of airfoils used on compressors and turbines. Also, there are situations when the shaft power of the turbine is meant to just drive the front rotary compressor and leave enough axial fluid energy to provide the jet reaction, and then there are those situations when the turbine shaft power is to be used not only to drive the rotary compressor but the gearbox for the turboprop or the fan where the engine thrust is obtained by the propeller or the fan, rather than the jet stream reaction. As a rule of thumb to satisfy the younger students, in order for them to have a quick grasp of the dynamics involved, I found it useful to suggest that in a compressor and a turbine and the burner it is useful to always think of ACCELERATION which is taking place. An air particle in a jet engine may be considered as having its position described by a Polar Coordinates in that an air particle is placed at a given radius "R" and an angle. " angle A" hence S is a function of (R)(A) hence the accelerations will include rotary and linear accelerations to which one would need to add the temperature effects. At the compressor stage, to increase the pressure one needs to slow down the air through the compressor rotor /stator blades while at the turbine one needs to accelerate the air to a higher speed during their travel through the hot turbine/stator blades. Since one is dealing with a thin slice in the discs that make the rotors and stators the logic to achieve a deceleration in the compressor is to have the air entering the blades at a narrow-angle with the face of the blade disc and leave the end of the blade closer to a right angle with the disc or parallel with the compressor shaft. This mechanical logic will produce a larger area as the air moves in the gap between the blades of the compressor. With the diffuser before the burner and other deceleration of air will ensure a higher pressure. With the hot turbine stage, for the hot burner air to be accelerated it enters the turbine blade almost at a right angle to the blade disc and leaves at an angle closer to the face of the disc. This mechanical logic ensures that the area of the space between the blades of a turbine and its associated stator gets smaller so the air gains velocity. The rotary or linear energy of the hot gas is controlled according to what is desired, to drive a pure jet or a turboprop or a fan. The concepts become a little complex when different turbines are used to drive different loads. In a jet engine using air as a medium, because the air is compressible, one may appreciate the compression and expansion of the cold or hot air that moves in between the blades at the compressor or a turbine stage, but in the case of a water propeller, since the water is incompressible, students find it more difficult to understand what actually happens between the blades of a water propeller regarding the velocity and pressure states, when the water between the blades of a sea propeller cannot change its volume. When one graduate to the surface and cavitating propellers which throw lumps of water, the aerodynamic and thermodynamic concepts provide a few hours of enjoyment in trying to understand the difference between water propellers and jet engine compressors. At the early stages of the steam turbine, Sir Charles Algernon Parsons at Newcastle upon Tyne who persuaded the Royal Navy that steam can be used to produce higher speed in Naval ships, he made the "TURBINA" 1894, the first turbine ship and when he came to draw the profile of the turbine shape, he doodled it down on a piece of paper using only his intuition of how he felt that steam pressure would behave around the accelerating stages of the rotor and stator of a steam turbine blade. It is said that 100 years later the turbine profile was analyzed by modern computers and it was found that Sir, Charles Parsons was not out by even 1% from the optimum shape. It seems that the early true engineers who built the machines became part of them and felt their way of shaping them. It seems that there are "Savants" who exhibits exceptional skill or brilliance in some limited field without needing a university education. There are savants in mathematical operations and also there are savants who feel their way through invisible and silent engineering functions and fluid operating in between compressor, propeller, fan, and turbine be it reaction or impulse, are fields which should be better presented even at the earlier schools even if the weather and winds and whirlwinds and dust devils and flying wings and birds and fish fluke/fin propulsion are made a little easier to understand by the general public.
@jamesmoses48102 жыл бұрын
Please sir, any difference between a steam turbine blade and a gas turbine blade? What are they in terms of design, protection, defects and corrections? Between the two blades which is much more efficient or better if the blades are switched? I await your reply as soon as possible, sir. Thank you!
@maherharoun73348 ай бұрын
if i would like to design an airfoil , what is the software used ?
@saibharathmarkondapatnaik60087 ай бұрын
XFLR5. I'm using it. But don't expect much from it. The advantage is that, we can get property graphs. But we can neither import not export advanced airfoils like NACA 6digit, Reflexed airfoils or any other Airfoils that we design.
@grahamflowers Жыл бұрын
The gyro wind turbine has smashed Betz limit watch KZfaq video regards Graham Flowers