Gas Turbine Rotor Blade Tip Clearance Flow Control
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Solution Overview
Problem
Gas turbine engines face significant energy losses and instability due to rotor tip clearance flow leakage, which leads to aerodynamic turbulence, reduced efficiency, and potential damage from flutter or forced vibrations.
Innovation Solution
The implementation of plasma actuators powered by inductive coils and magnets, which use time-varying magnetic flux to induce electrical power and create an electric field to ionize air, reducing tip clearance flow leakage and mitigating vibrations by actively controlling airflow.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If rotor blade tip clearance is reduced to improve compression efficiency, then energy loss decreases, but aerodynamic turbulence and instability increase due to blade tip contact with the compressor case
Solution Approach 1:
A plasma actuator is introduced as an intermediary device between the rotor blade tip and the compressor case. The plasma actuator generates an electric field that ionizes the air in the tip clearance region, creating a plasma barrier that prevents direct contact between the blade tip and case while controlling the leakage flow. This mediator allows the blade tip to maintain reduced clearance for efficiency without experiencing direct mechanical contact and associated instabilities.
Solution Approach 2:
The invention changes the physical state of the air in the tip clearance region from neutral gas to ionized plasma. By applying high voltage through the plasma actuator, the air molecules are ionized, fundamentally altering the fluid properties and enabling active control of the leakage flow. This parameter change allows for dynamic adjustment of flow characteristics to prevent turbulence and instability.
2Loss of energy
If rotor blade tip clearance is reduced to improve efficiency, then energy loss decreases, but the risk of blade tip contact and mechanical damage increases
Solution Approach 1:
The plasma actuator serves as a protective intermediary that maintains an ionized barrier between the rotor blade tip and the compressor case. This plasma layer prevents direct mechanical contact while allowing the blade tip to operate at reduced clearance for improved efficiency. The mediator function protects blade integrity without sacrificing aerodynamic performance.
Solution Approach 2:
The plasma actuator is positioned upstream of the blade tip clearance region to preemptively ionize the air and control the leakage flow before it can cause mechanical contact. By acting in advance, the system prevents blade tip contact and potential damage before it occurs, enhancing reliability while maintaining efficiency.
3Productivity
If plasma actuators are added to control tip clearance flow, then airflow directionality and efficiency improve, but device complexity increases
Solution Approach 1:
The invention extracts the power source for the plasma actuator from the main engine system by using an inductive coil that generates power wirelessly through electromagnetic induction. The coil is positioned to inductively couple with the plasma actuator, eliminating the need for physical electrical connections and reducing system complexity. This extraction of the power source simplifies the overall system while maintaining airflow control efficiency.
Solution Approach 2:
The invention replaces traditional mechanical electrical connections with an electromagnetic inductive power transmission system. Instead of using wires or slip rings to power the plasma actuator, an inductive coil generates an alternating magnetic field that induces current in the actuator. This substitution eliminates mechanical contact points and reduces system complexity while maintaining effective plasma generation.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This solution significantly reduces energy losses, enhances operational efficiency, and minimizes damage by improving airflow directionality and reducing flutter and forced vibrations in gas turbine engines.
Implementation Method 1
plasma actuators powered by inductive coils and magnets, which use time-varying magnetic flux to induce electrical power
Implementation Method 2
create an electric field to ionize air, reducing tip clearance flow leakage
Data Source
AI summary
A gas turbine engine system includes a drive shaft and a compressor located in a compressor case. The compressor has a number of rotors. Each rotor includes a number of blades radially extending from a rotor wheel and terminating in a blade tip. The blade tip terminates in close proximity to the case and defines a tip clearance. An air flow control system is coupled to the compressor. The air flow system includes inductive coils and plasma actuators coupled to the case and magnets coupled to the blade. The plasma actuators induce air flows in order to, for example, mitigate air flow leakage around the tip of the blade.