--- title: "Gas turbine engine components and arrangement" subject: "Turbo Machines" chapter: 3 key: "semester_7/turbo_machines:gas-turbine-engine-schematic-components" source: https://www.bctengineer.com/q/semester_7/turbo_machines/gas-turbine-engine-schematic-components site: BCT Engineering --- # Gas turbine engine components and arrangement Turbo Machines · Chapter 3: Gas Turbine - Asked in: year not given, 3+3 marks - Video: [What is a Gas Turbine? (For beginners)](https://www.youtube.com/watch?v=BUn5-0VG3Hw) — RealPars - Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14 - Page: https://www.bctengineer.com/q/semester_7/turbo_machines/gas-turbine-engine-schematic-components - Whole chapter: https://www.bctengineer.com/md/semester_7/turbo_machines/chapter-3 ## Question Draw the schematic diagram of a simple open-cycle gas turbine plant and explain the function of each component. Differentiate between open and closed cycle gas turbine plants. ## Short answer Main components: compressor raises air pressure; combustion chamber burns fuel at constant pressure; turbine expands hot gases to produce work. In open-cycle, air is drawn from and exhausted to atmosphere; closed-cycle recirculates a clean working fluid through an external heater and cooler, allowing higher pressures and any fuel source but is bulkier and costlier. ## Answer #### Schematic of the open-cycle gas turbine ```text fuel | +---+ v +-----------+ +---+ air ---->| C |------------>| Combustor |----->| T |----> exhaust +-+-+ +-----------+ +-+-+ | | +-------------- shaft ---------------+----> load ``` #### Functions 1. **Compressor (C):** axial or centrifugal; raises the pressure of the air from atmospheric to $p_2$ (pressure ratio 6 to 30). It absorbs 50 to 60% of the turbine work. 2. **Combustion chamber:** fuel is burnt at nearly constant pressure with only part of the air (primary air); the rest dilutes and cools the gases to the turbine limit (about 1100 to 1500 K). 3. **Turbine (T):** the gases expand to atmospheric pressure and develop work. Part of it drives the compressor; the remainder is the net output. 4. **Starting motor, fuel pump, lubricating system and other auxiliaries.** #### Open and closed cycle | Point | Open cycle | Closed cycle | |---|---|---| | Working fluid | Air drawn from and exhausted to the atmosphere | The same gas (air, helium) circulates repeatedly | | Heating | Internal combustion in the chamber | External heater (heat exchanger) | | Cooling | Exhaust to the atmosphere | A cooler brings the gas back to the compressor inlet state | | Fuel | Clean liquid or gaseous fuel only | Any fuel, even coal or nuclear heat | | Pressure level | Atmospheric at the inlet | Can be raised, giving smaller machines | | Size, cost | Compact, cheap | Larger and costly (heat exchangers) | | Blade fouling | Possible with dust and ash | None, clean working fluid | | Use | Aircraft, power plants, peak load | Special plants, nuclear and solar | The open cycle is far more common because of its simplicity, light weight and quick start. ## Check yourself The answer's key points as multiple-choice questions, with the correct option and why. 1. What are the main components of a simple open-cycle gas turbine? A. Boiler, turbine, condenser B. Compressor, combustion chamber, turbine C. Pump, heater, nozzle D. Compressor, condenser, evaporator Answer: B. Air is compressed, fuel is burnt in the combustor, and gases expand in the turbine. (Key point: Cycle components) 2. How is the compressor driven? A. By a separate motor only B. By the atmosphere C. By part of the turbine output through the shaft; the remainder is net output D. By the combustion chamber directly Answer: C. The compressor absorbs 50-60% of turbine work; the rest is net output. (Key point: Turbine and compressor work) 3. Why does only part of the air burn fuel in the combustor? A. The rest is wasted B. Rest of the air dilutes and cools the gases to the turbine temperature limit C. To raise exhaust pressure D. To avoid compressor surge Answer: B. Primary air burns the fuel; the remaining air cools gases to about 1100-1500 K. (Key point: Primary and dilution air) 4. Which is true of the closed-cycle plant? A. It uses internal combustion in the chamber B. It exhausts to the atmosphere C. Fuel must be clean liquid or gas D. The same gas circulates, heated externally, so any fuel can be used and blades stay clean Answer: D. Closed cycle uses an external heater and cooler, allowing coal or nuclear heat and no blade fouling. (Key point: Open vs closed) ## Related in Turbo Machines - [Actual gas turbine cycle with component efficiencies](https://www.bctengineer.com/question.md?key=semester_7%2Fturbo_machines%3Aactual-brayton-cycle-numerical) — Turbo Machines, chapter 3 - [Modifications of the basic gas turbine cycle](https://www.bctengineer.com/question.md?key=semester_7%2Fturbo_machines%3Avariations-basic-gas-turbine-cycle) — Turbo Machines, chapter 6 - [Gas turbine power from isentropic efficiency](https://www.bctengineer.com/question.md?key=semester_7%2Fturbo_machines%3Agas-turbine-power-isentropic-efficiency) — Turbo Machines, chapter 1 - [Axial gas turbine stage design calculation](https://www.bctengineer.com/question.md?key=semester_7%2Fturbo_machines%3Aaxial-turbine-stage-gas-numerical) — Turbo Machines, chapter 2 - [Gas turbine combustion chamber: requirements and types](https://www.bctengineer.com/question.md?key=semester_7%2Fturbo_machines%3Acombustion-chamber-requirements-types) — Turbo Machines, chapter 3 - [Gas turbine nozzle: principle and types](https://www.bctengineer.com/question.md?key=semester_7%2Fturbo_machines%3Anozzle-principle-types) — Turbo Machines, chapter 4 ## Related in other subjects - [Closed gas turbine cycle components; thermal efficiency](https://www.bctengineer.com/question.md?key=semester_2%2Ffundamental_of_thermodynamics_and_heat_transfer%3Aclosed-gas-turbine-cycle-efficiency) — Fundamental of Thermodynamics & Heat Transfer, chapter 6 - [Open cycle gas turbine with intercooling](https://www.bctengineer.com/question.md?key=semester_7%2Fpower_plant_equipment%3Agt-intercooling-sketch) — Power Plant Equipment, chapter 6 - [Open cycle gas turbine on heavy oil](https://www.bctengineer.com/question.md?key=semester_7%2Fpower_plant_equipment%3Agt-heavy-oil-capacity) — Power Plant Equipment, chapter 6 - [Reheat gas turbine power plant](https://www.bctengineer.com/question.md?key=semester_7%2Fpower_plant_equipment%3Agt-reheat-plant) — Power Plant Equipment, chapter 6