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Theoretically, it is the difference between the gross and net thrust (Momentum drag = Gross thrust – Net thrust). It is computed as:
Net thrust is a positive aerodynamic force that causes propulsion of an aircraft in air. It is represented as a summation nozzle thrust and momentum of the jet’s motion. It is a resultant propulsion force produced by the jet engine used in providing thrust (speed) to the aircraft. It is the difference between the gross thrust and the momentum drag on the engine of an aircraft (Net thrust = Gross thrust – Maximum drag). It is usually denoted by T and is calculated as follows:
The engine thrust is affected by the flow of air into the engine and is thus a change in the rate of airflow results to a change in the resultant thrust. With net thrust, the increase in the aircrafts speed results to an increase for air fed into the engine, resulting to a higher output. With static thrust, the environmental factors tend to determine the ability of the craft to cause motion. With static thrust, the air speed is kept constant and is not affected by the crafts motion thus differing from the net thrust.
b) Calculate the net thrust of a turbo jet flying at 150 M/S with an air mass flow of 50 Kg/S and a jet stream velocity of 300 M/S with a chocked nozzle. The residual gas pressure in the jet stream is 45 KPa gauge, the nozzle area is 0.2M2.
Net thrust = gross thrust – momentum drag (T = mVj + Aj (Pj - Pam) – mVi) where Pam is the ambient air pressure in question. Form this equation an increase in the ambient air pressure, while holding all other factors constant results to a decrease in the net thrust of the engine, which being the denominator of the SFC formula results to an increase in the resultant value of the specific fuel consumption. As indicated by the new SFC equation
Propulsive efficiency = (2Vi) / (Vi + Vj), where Vi is the speed of the exhaust gases and Vj is the incoming air speed. Increasing the speed of the gas
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Potential appraisal aims at identifying those skills of which the employees might not even be aware. Potential appraisal is future oriented, as it is used to consider the ability of the employee to be promoted. Potential appraisal may be used as a tool to predict the performance of an employee by identifying his strengths and weaknesses beforehand.
Turbojets with converging-diverging nozzle (Sherwin, Keith & Michael, Horsley, 1996) There is an upstream rotating compressor that is coupled to a downstream turbine, and a combustion chamber in-between, and the accelerated gases moving through the engine nozzle is used to provide thrust, which drives the aircraft.
The author explains that compressor can be either of axial flow or of centrifugal (radial) flow type. In axial flow compressor, the air is compressed as it flows along the axis of the shaft towards the rear of the compressor whereas, in the centrifugal flow compressor, the air is compressed and accelerated in an outward direction.
However, FADEC system is the most common system in most engines. The FADE system is a system in which the engine is under the full control of an electronic microprocessor and the sensors that measure RPM, atmospheric pressure, oil pressure, MAP, CHT, and EGT.
Limiting this effect decreases the power of the diesel and thus hurts the power of the engine overall. However, the recent focus on the environmental movement and focus on global warming with documentaries such as Al Gore's An Inconvenient Truth has brought a good deal of media attention to the environment, and as such, diesel engines have had to undergo some re-examination.
The expanding gases are used to turn the turbine, which helps to keep the engine in operation as it drives the compressor through the shaft (FOPPGS 1). Finally, the accelerated gases moving through the engine nozzle is used to provide
The engine overhaul process is an involving task that requires many aspects to be covered. One of the primary concerns is the technology that would be used to ease the process. Several systems and software can be employed to achieve this task. One of the systems that could be employed is the interactive maintenance manual.
Most performance budgets places emphasis on employees’ commitment to provide quality results to the satisfaction of the public.
Performance based budgeting has great characteristics that has made it quite suitable in public sector budgeting for local governments.
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