HW5b_09 Solution

# HW5b_09 Solution - ME 18b HW 5 Due Thursday(accepted until...

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1 ME 18b, HW 5 Due Thursday May 14, 2009 (accepted until 4 pm) Note: This homework is due on a Thursday not a Tuesday TAs for HW #5: Dan Alvarez, Sunday 8-10 pm, SFL 229; Mary Dorman, Monday 7-9 pm, SFL 331 Number of classes attended: ______ Hours spent on homework: _______ 1. Brayton Cycle Jet Aircraft Engine The General Electric GE90 is a family of high- bypass turbofan engines built by GE-Aviation for the Boeing 777, with thrust ranging from 74,000 to 115,000 lbf (329 to 512 kN). It was first introduced in November 1995. The GE90 series are physically the largest engines in aviation history. The fan diameter of the latest variant, the GE90-115B, has a diameter of 325 cm (128 in). This means that the GE90 has a diameter larger than most cabins in business aircraft. For more info on this engine go to: http://www.turbokart.com/about_ge90.htm Using the state numbers shown in the figure below for your analysis; determine the following operating conditions of the engine as power is applied prior to take-off while the plane is still stationary on the runway: a. Air mass flow rate for a thrust of 400 kN. b. Air volumetric flow rate in m 3 /min and cfm. c. The work of the fan, compressor and turbine. The fan has a pressure ratio of 2.1 and the compressor has a pressure ratio of 19.0. Ignore the portion of fan work that provides bypass air (which is not shown). d. The heat input for final combustion temperature of T 5 = 1400 K. e. The exhaust velocity f. The fuel consumption in kg/hr if the fuel has a heating energy value of 45 MJ/kg. You will need to make your own assumptions about the inlet conditions.

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2 Solution: Assume inlet conditions are 100 kPa and 295K and Vin = 0. A reasonable pressure range would be from about 75 kPa to 102 kPa for a ground level of 7500 ft to -200 ft above sea level. A reasonable temperature range would be from -40° to +40°C (cold Canadian winters to hot desert summers). State 1: T1 = 22°C, 295K, h1 = 296 kJ.kg, Pr1 = 1.053
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HW5b_09 Solution - ME 18b HW 5 Due Thursday(accepted until...

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