The role of plasma actuator is investigated for separation control and lift enhancement. During actuation the electrons around the atomic nucleus reach an exited state at higher temperatures as a result of which the electron leaves the orbit. Thus an ionized gas with the liberation of plasma is observed. The experimental setup consists of two copper inserts placed on either side of a dielectric material. An input voltage of approximately 5 kV is supplied to the copper strips creating the region of plasma observed as a bright light. Consequently the flow field is provided with a higher momentum and energy due to the creation of the body force.                       

 

Experiments are conducted on a flat plate for a quiescent case to analyze the average and instantaneous velocity for different waveforms. The study involves the actuation at various input frequencies ranging from 4-5 kHz. PIV technique is carried out to understand the velocity of the flow as well as its effects in the downstream direction.

             

Flat plate: Instantaneous velocity 

Flat plate: Velocity profiles at various regimes

 

Observations obtained with the flat plate geometry forms the basis to control flow separation in low pressure turbine blades. For Reynolds number of 25000, 30000 and 50,000, PIV as well as flow visualization techniques are conducted to analyze the reattachment of the flow and to reduce the region of separation. Phase lock PIV, and pulsing techniques are performed for various forcing frequencies ranging from 0.1 to 1. This demonstrates the appearance of primary and secondary vortices which initiates the control of separation by adding strength to the flow. Further the investigation of power due to actuation is calculated using the current and voltage measurement transducers to assess the optimal use of the active flow control method.

 

     

 

           LPT blades:  PIV technique

 

    

Primary and secondary vortices 

            

Current and voltate draw

 

Experiments are conducted to determine the use of plasma actuators on finite wing to improve the aerodynamic characteristics. The actuator is placed on a wing of finite aspect ratio at low speeds to perform the role of ailerons and winglets. The test is conducted for a Reynolds number of 30,000 with a positive and negative angle of attack of 14¼ to visualize the wake characteristics. The relative changes in the lift are obtained using the vortex strength and Kutta-Zhuhovski theorem.

    

 

Plasma actuators placed on various portions of a wing

 

Positive increases in lift up to 92 % are observed in 3 cases while a decrease in lift is measured in a single case. For the plasma aileron, useful for maneuvering, the total change in lift is approximately 60 % of the baseline lift in the upward position and -30% in the downward position. These characteristics of plasma actuators strongly exhibit the increase in momentum and suction with the influence of turbulence in the flow.