ME3264: LAB 9 Gas Turbine Power System

Transcription

1 OBJECTIVE ME3264: LAB 9 Gas Turbine Power System Professor Chih-Jen Sung Spring 2013 A fully integrated jet propulsion system will be used for the study of thermodynamic and operating principles of gas turbine power systems. The core gas-generator is representative of all major gas turbine types and permits analysis of air equivalent Brayton and Gas Turbine cycles. The compact turbojet engine, SR-30, features a centrifugal flow compressor, reverse flow annular combustor, and an axial flow turbine stage. Following the fundamental gas turbine cycle, (1) ambient air enters the engine through the bell shaped inlet; (2) the air is then compressed, diffused, and directed into the combustor can; (3) kerosene-based fuel, introduced via six high-pressure atomization nozzles, is mixed with the compressed air and ignited; (4) heated combustion gas expands and accelerates through the vane guide ring causing the turbine to rotate; (5) useful work is extracted from this rotation as the turbine powers the compressor; (6) the combustion gases are further accelerated through the thrust nozzle where the remaining heat energy is converted to kinetic energy in the form of jet thrust; and (7) the ejected gas returns to ambient atmospheric conditions thereby completing the thermodynamic cycle. With measured values of compressor inlet temperature and pressure, turbine inlet temperature and pressure, turbine exit temperature and pressure, and fuel flow, the following experiments can be conducted. 1. Thrust Specific Fuel Consumption Analysis: determine the optimal operational setting for the SR-30 Gas Turbine by analyzing the fuel consumption rate verses the amount of thrust generated. 2. System Analysis: perform system performance calculations using First Law Energy Conservation Equation for steady flow conditions. PREPARATION 1. Review textbook * materials on Brayton cycle. 2. Review the steps to be taken in order to determine the efficiency of the cycle in terms of thermodynamic quantities. 3. Watch the videos posted on HuskyCT about starting and operating this gas turbine power system. 4. Attend a demonstration session to get familiar with this gas turbine power system and observe the start-shutdown procedure. (1) Sign up for a demonstration run in late March or early April (TBA). (2) You must attend a demonstration session to be able to take data in the actual lab in the week of April 22 nd. * M.J. Moran and H.N. Shapiro, Fundamentals of Engineering Thermodynamics, Seventh Edition, Chapter 9. Prof. Chih-Jen Sung Page 1 of 6 Spring 2013

2 5. Homework: (1) A stationary gas turbine power plant operates on a simple ideal Brayton cycle with air as the working fluid. The air enters the compressor at 95 kpa and 290 K and the turbine at 760 kpa and 1100 K. Heat is transferred to air at rate of 35,000 kj/s. Determine the power delivered by this plant (i) assuming constant specific heats at room temperature and (ii) accounting for the variation of specific heats with temperature. (2) Consider an aircraft powered by a turbojet engine that has a pressure ratio of 12. The aircraft is stationary on the ground, held in position by its brakes. The ambient air is at 300 K and 95 kpa and enters the engine at a rate of 10 kg/s. The jet fuel has a heating value of 42,700 kj/kg, and it is burned completely at a rate of 0.2 kg/s. Neglecting the effect of the diffuser and disregarding the slight increase in mass at the engine exit as well as the inefficiencies of engine components, determine the force that must be applied on the brakes to hold the aircraft stationary. EQUIPMENT 1. The figure below shows the SR-30 gas turbine cutaway and engine sensor locations. Prof. Chih-Jen Sung Page 2 of 6 Spring 2013

3 2. The control panel of this gas turbine power system is shown below. 3. A data acquisition laptop connects to the unit s data acquisition system via USB port as well as displays and captures data for operation and analysis. 4. Operational and data acquisition instrumentation includes the following. Prof. Chih-Jen Sung Page 3 of 6 Spring 2013

4 EXPERIMENTAL AND REQUIREMENTS I. Thrust Specific Fuel Consumption Analysis To run the turbine power system, the start procedure from the MiniLab TM Gas Turbine Operation Manual will be followed. A TA will be on hand to assist. All data needed for the analysis assignments will be downloaded into an Excel file. You must bring a thumbdrive to save your data to. The engine operates from a laptop NOT connected to our network. A snapshot of the file is shown below: Select at least four RPM settings (from low to highest operating RPM in the range of 40,000 80,000 RPM) for your run. Plot Fuel Flow and Thrust over time on one graph. Plot RPM over time. Calculate Thrust Specific Fuel Consumption at each RPM setting. At what power setting does the SR-30 gas turbine offer the best and worst Thrust Specific Fuel Consumption? Discuss your results. Prof. Chih-Jen Sung Page 4 of 6 Spring 2013

5 II. System Analysis Choose a dataset for a particular RPM taken in Part I. Carry out the system analysis on this dataset. A schematic of Brayton cycle for gas turbine and cutaway of SR-30 engine is shown in the following. Using air tables, determine the specific enthalpy (in kj/kg) at each cycle point. For the compression stage, determine the specific work (in kj/kg) done by the compressor. For the combustion stage, determine the specific energy (in kj/kg) added by the fuel. For the turbine expansion, determine the specific work (in kj/kg) of the turbine. Determine the specific work (in kj/kg) done by the cycle. Determine the thermodynamic efficiency of the cycle. Discuss your results. Prof. Chih-Jen Sung Page 5 of 6 Spring 2013

6 APPENDIX Gas Turbine Power System Specifications Prof. Chih-Jen Sung Page 6 of 6 Spring 2013