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Answer: In an actual compressor, towards the exit of the impeller, the Coriolis pressure gradient disappears. This leads to a difference in the relative whirl/tangential velocity and the blade speed. This causes the relative whirl/tangential velocity to lag behind the blade speed resulting in slip.
Answer: Brijesh: please refer to Chapter 5 of book Mechanics and Thermodynamics of Propulsion by Hill and Peterson. Detailed description of variation of SFC of different types of engines with altitude is given there.
Answer: Thanks for pointing out the error. This slide was supposed to have been replaced by the editors. Will ask them to do so as soon as possible.
Answer: Thanks for pointing out the error. The correct formula is Rx=Ca/2U x {tan(beta1)+tan(beta2)}
Answer: Please refer to any of the books, say by Dixon or by Hill and Peterson for a detailed derivation.
Answer: It is the ratio that is equal and not the temperatures. The ratios are assumed to be equal for a fully expanded nozzle. Therefore the pressure ratios and the Mach numbers come out to be equal too. The individual temperatures are not assumed to be equal.
Answer: There is no fixed distance that must be attained for escaping the earth's gravitational. A powered spececraft can straigtaway be propelled out of earth's orbit. Most of the times for controlled mission they are made to orbit a few times before going out for space missions. A loose way to put it is wherever it attains escape speed it goes out of earth's gravity field.
Answer: Choked nozzle refers to a state of operation on the nozzle wherein the nozzle has accommodated or passes the maximum possible mass flow under the given conditions of pressure ratio, and area ratio. In this condition, the Mach number at the throat of the nozzle becomes unity. For a supersonic nozzle, the nozzle has to be choked at the throat to achieve supersonic flow in the diverging portion of the nozzle. Aero engines operate under choked condition most of the time ensuring best possible performance of the engine under various operating conditions.
Answer: I can only give you a hint for this question: the thrust equation is derived in such a way that thrust is always along the axis of motion. Therefore, if the exhaust is deflected, there would not be any thrust due to this exhaust. However what about the flight speed?
Answer: A supersonic flow cannot be obtained in a converging nozzle. So, if the flow entering the nozzle itself if sonic or supersonic, there would a normal shock/bow shock upstream or at the nozzle lip (depending upon the nozzle angle and Mach number). Downstream of this shock, the flow would be subsonic and then would accelerate in the converging nozzle.
Answer: A stator by its name is a stationary set of blades. It is aerodynamically matched to the rotor only when it is stationary. If it is made to rotate (somehow) it will be automatically unmatched with the rotor and the efficiency and pressure ratio will fall drastically.
Answer: Please let me know the corresponding slide numbers. Thanks.
Answer: You could also use the per stage pressure rise to determine the number of stages. Here again the assumption of equal pressure rise per stage will be implied.
Answer: Degree of reaction is a two dimensional estimate of share of diffusion between rotor and stator. In a centrifugal compressor the rotor is a highly 3-D machine - there is no scope for such 2-D concepts to be utilized.
Answer: Air-breathing engines are those that use air from the atmosphere for combustion. All jet engines, petrol and diesel engines etc are air-breathing engines. Non-airbreathing engines on the other hand carry an oxidiser (not necessarily oxygen) for combustion. Rocket engines are examples of these type of engines.
Answer: Addition of alcohol to petrol is being practiced in many countries. Though the overall efficiency may not change significantly, it does help reduce to consumption of fossil fuels.
Answer: Boat tail drag occur outside the nozzle - on the outside surface of the nozzle body - and not inside the nozzle. Due to the rear body shape of the nozzle body - like a boat tail - the aerodynamic drag experienced by such a shape is called a boat tail drag.
Answer: The net thrust produced by the engine is a sum total of thrusts experienced by all the components, intake, fan/compressor, combustor, turbine and the nozzle.
Answer: I am not sure if I understand your question correctly. Why would one want to match a centrifugal compressor to a diesel engine? If the requirement is to generate compressed air with a centrifugal compressor driven by an engine, then the engine needs to run at speeds that the compressor has been designed for. The compressor performance map should be used to arrive at this number.
