How Jet Engine Works | Part 3 : Performance

Summary

This video dives deep into the performance control of the GE90 engine, focusing on how its Full Authority Digital Engine Control (FADEC) system works. The engine’s performance is optimized through sensors, actuation mechanisms, and feedback loops to manage airflow and maintain efficiency across various thrust settings. Key systems like the Variable Bleed Valve (VBV), Variable Stator Vanes (VSV), and Active Clearance Control (ACC) ensure the engine operates efficiently, preventing issues like compressor stalls and energy loss. This in-depth overview highlights the advanced technology that keeps the GE90 engine performing at its best across different operating conditions.

Takeaways

• 😀 The GE90 engine operates on a Full Authority Digital Engine Control (FADEC) system, which integrates sensors, computers, and actuators to optimize performance.
• 😀 The engine performance is monitored and controlled by the Electronic Engine Control (EEC), which collects data from various sensors.
• 😀 Key sensors include N1 and N2 speed sensors, temperature probes, and pressure sensors that provide critical data to the EEC for performance calculations.
• 😀 The Variable Bleed Valve (VBV) system manages airflow between the low-pressure and high-pressure compressors to prevent compressor stalls and maintain engine efficiency.
• 😀 The Variable Stator Vanes (VSV) system optimizes airflow in the high-pressure compressor, reducing stall risks and ensuring better performance at low speeds.
• 😀 As engine speed increases, the VBV and VSV systems adjust to improve airflow and maintain engine stability.
• 😀 Active Clearance Control (ACC) systems manage the tip clearance of the turbine blades to reduce energy loss and maintain optimal power output.
• 😀 The High Pressure Turbine (HPT) and Low Pressure Turbine (LPT) Active Clearance Control (ACC) systems use different mechanisms (servo fuel pressure and pneumatic pressure) to adjust clearance and enhance turbine efficiency.
• 😀 The EEC commands the operation of the VBV, VSV, and ACC systems to adjust to changing engine conditions and ensure maximum fuel efficiency.
• 😀 The GE90 engine’s performance systems work together to balance power output, fuel efficiency, and engine longevity by making real-time adjustments based on sensor feedback.

Q & A

What is the full authority digital engine control (FADEC) system, and how does it relate to the GE90 engine's performance?

The FADEC system is a complex, closed-loop system that controls all aspects of engine performance except for fuel control. It involves sensors, computers, actuation mechanisms, and feedback systems that ensure the engine operates efficiently at all power settings.

What are the main types of sensors used in the GE90 engine for performance monitoring?

The GE90 engine uses several sensors, including N1 and N2 speed sensors, temperature probes, and pressure sensors. These sensors monitor various aspects such as shaft RPM, engine gearbox speed, air and exhaust temperatures, and pressures at key locations like the high-pressure bleed duct and combustion inlet.

How does the GE90 engine manage airflow at low power settings?

At low power settings, the GE90 engine uses the variable bleed valve (VBV) system to control the airflow exiting the low-pressure compressor. This prevents overloads in the high-pressure compressor and avoids compressor stalls, maintaining engine stability.

What role do the variable stator vanes (VSV) play in the GE90 engine?

The VSV system controls the airflow in the high-pressure compressor by adjusting the angle of the stator vanes. This helps maintain efficient airflow, prevent compressor surging, and ensure that the engine remains within the stall margin during low-speed operation.

What is compressor stall, and how does the GE90 prevent it?

Compressor stall occurs when the airflow through the compressor becomes unstable, leading to performance breakdowns. The GE90 prevents this by using systems like the VBV and VSV to regulate airflow and stator angles, ensuring optimal performance even at low speeds.

How does the GE90 engine prevent energy loss due to thermal expansion in the turbine section?

The engine uses active clearance control systems in both the high-pressure turbine (HPT) and low-pressure turbine (LPT). These systems maintain minimum tip clearance by regulating the temperature of the turbine casing, which reduces energy loss and improves efficiency.

What happens when the engine is running at high speeds in terms of fuel consumption and efficiency?

At higher speeds, the engine burns more fuel, which increases the temperature in the turbine and exhaust sections. However, this also leads to thermal expansion, increasing the gap between turbine blades and the casing, causing energy loss. Active clearance control systems mitigate this to maintain efficiency.

What is the purpose of the feedback signals sent by sensors in the GE90 engine?

The feedback signals from sensors, like the position of bleed valves and stator vanes, provide real-time data to the Electronic Engine Control (EEC). This allows the EEC to adjust engine parameters dynamically, ensuring optimal performance across various operating conditions.

How does the GE90 engine handle varying thrust requirements during operation?

The GE90 engine adjusts its performance using systems like the VBV and VSV to manage airflow and compressor efficiency. These systems allow the engine to handle varying thrust levels while maintaining stability and preventing issues like compressor surging.

What will be covered in the fourth installment of the GE90 engine series?

The fourth installment of the GE90 engine series will focus on the engine protection systems, which help safeguard the engine from potential damage during operation by monitoring and responding to abnormal conditions.