Question

Turbojet engine is traveling at altitude where the ambient pressure is 90 kPa and temperature is -30°C. The pressure ratio across the inlet diffuser is 1.5:1 and the compression is assumed to be isentropic. Air then enters the compressor with a compression ratio of 4:1 and with a velocity of 50 m/s and leaves with a velocity of 75 m/s. Assume that the compression in the compressor is isentropic. If the mass flow rate is 0.25 kg/s, find the power required to drive the compressor. Assume γ = 1.4 and CP = 1.005 kJ/kg.

          Turbojet engine is traveling at altitude where the ambient pressure is 90 kPa and temperature is -30°C. The pressure ratio across the inlet diffuser is 1.5:1 and the compression is assumed to be isentropic. Air then enters the compressor with a compression ratio of 4:1 and with a velocity of 50 m/s and leaves with a velocity of 75 m/s. Assume that the compression in the compressor is isentropic. If the mass flow rate is 0.25 kg/s, find the power required to drive the compressor. Assume γ = 1.4 and CP = 1.005 kJ/kg.
        
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University Physics with Modern Physics
University Physics with Modern Physics
Hugh D. Young 14th Edition
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Turbojet engine is traveling at altitude where the ambient pressure is 90 kPa and temperature is -30°C. The pressure ratio across the inlet diffuser is 1.5:1 and the compression is assumed to be isentropic. Air then enters the compressor with a compression ratio of 4:1 and with a velocity of 50 m/s and leaves with a velocity of 75 m/s. Assume that the compression in the compressor is isentropic. If the mass flow rate is 0.25 kg/s, find the power required to drive the compressor. Assume γ = 1.4 and CP = 1.005 kJ/kg.
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Air is compressed by an adiabatic compressor from 100 kPa and 20°C to 1.8 MPa and 400°C. Air enters the compressor through a 0.15 m^2 opening with a velocity of 30 m/s. It exits through a 0.076 m^2 opening. Calculate the mass flow rate of air and the required power input. The constant pressure specific heat of air at the average temperature of 210°C = 483 K is cP = 1.026 kJ/kg·K. The gas constant of air is R = 0.287 kPa·m^3/kg·K. The mass flow rate of air is kg/s. The required power input is kW.

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A turbojet aircraft is flying with a velocity of $280 \mathrm{~m} / \mathrm{s}$ at an altitude of $9150 \mathrm{~m}$, where the ambient conditions are $32 \mathrm{kPa}$ and $-32{ }^{\circ} \mathrm{C}$. The pressure ratio across the compressor is $12,$ and the temperature at the turbine inlet is $1100 \mathrm{~K}$. Air enters the compressor at a rate of $50 \mathrm{~kg} / \mathrm{s},$ and the jet fuel has a heating value of $42,700 \mathrm{~kJ} / \mathrm{kg}$. Assuming ideal operation for all components and constant specific heats for air at room temperature, determine $(a)$ the velocity of the exhaust gases, (b) the propulsive power developed, and $(c)$ the rate of fuel consumption.

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A turbojet aircraft is flying with a velocity of $280 \mathrm{m} / \mathrm{s}$ at an altitude of $9150 \mathrm{m},$ where the ambient conditions are $32 \mathrm{kPa}$ and $-32^{\circ} \mathrm{C} .$ The pressure ratio across the compressor is $12,$ and the temperature at the turbine inlet is 1100 K. Air enters the compressor at a rate of $50 \mathrm{kg} / \mathrm{s}$, and the jet fuel has a heating value of $42,700 \mathrm{kJ} / \mathrm{kg}$. Assuming ideal operation for all components and constant specific heats for air at room temperature, determine ( $a$ ) the velocity of the exhaust gases, $(b)$ the propulsive power developed, and $(c)$ the rate of fuel consumption.

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Transcript

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00:01 Hi, in this question we have air which is compressed by an adiabatic compressor from 100 kpa.
00:09 So we have p1 given as 100 kpa and the value of inlet temperature of air that is t1 is equals to 20 degree celsius to p2 which is 1 .8 mpa and at temperature 400 degree celsius.
00:32 So now air enters the compressor through a opening having area given as 0 .15 m2 with a velocity of 30 m per second and it exits through the area a2 given as 0 .076 m2.
00:55 So we have to calculate the mass flow rate of air and the required power input.
01:01 Now from ideal gas equation we can write that the value of rho1 will be equals to p1 divided by rt1.
01:14 So we will get this value as 100 divided by r which is 0 .287 into 20 plus 273 as it was in 400 degree celsius.
01:27 So we get the value of rho1 as 1 .189 kg per meter cube.
01:37 So the mass flow rate of air that is m is equals to rho1 a1 v1.
01:47 So we can calculate the value of m as 1 .189 into 0 .15 into 30 which gives the value of mass flow rate of air as 5 .3505 kg per second.
02:12 Now density of air at exit can be calculated as rho2 equals to 1800 divided by 0 .287 into 400 plus 273...
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