Problem 3-2-21 Part A In an isentropic nozzle, operating at steady state, the sp

Question

Problem 3-2-21 Part A In an isentropic nozzle, operating at steady state, the specific flow energy i) and specific entropy (a) remain constant along the flow. The following properties are known at the inlet and exit ports of an isentropic nozzle discharging water at a steady rate of 2 kg/s. Inlet Pi 300kPa A,-3cm?: Exit P-100 kPa Determine the exit velocity (V) Use the St model for iquid water Express your answer in meters per second to lour significant figures. -16.667 m/s Incorrect; Try Again; 3 attempts remaining Part B Determine the exit area (42) Express your answer in square millimeters to three signiticant figures 0.0389 My Answers Give Up Incorrect, Try Again; 5 attempts remaining Part C wha Scenario what would te ext velody be r te ilet kinetic energy were neglected? Express your answer lin meters per second to four signilicant figures m/s

Explanation / Answer

Density of water at 300 kPa = 931.81 kg/m^3

Density of water at 100 kPa = 958.64 kg/m^3

mass flow rate = 2   = rho1 * A1 * V1 = rho2 ( A2 * V2)

V1 = 2 / 931.81 * 3 * 10^-4   = 7.1545 m/s

A2 * V2 = 2 / 958.64 = 0.00208 m^3/s

Specific flow energy is a constant

h1 + v1^2 / 2 = h2 + v^2 /2

561455 + 7.1545^2 / 2 = 471436 + v2^2/2

(a) v2 = 424.37 m/s

(b) A2 = 0.00208 / 424.37 = 0.049 cm^2

(c) If inlet kinetic energy is neglected then

      V2^2 / 2   = h1 - h2   = 561455 - 471436 = 90019

      V2 = 424.31 m/s

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