Experimental study on basic characteristics of high performance plasma jet actuator

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A high performance plasma jet actuator (HPJA) has been developed to address the challenges of ignition difficulty and low combustion efficiency in ramjet combustors operating under transition mode and low pressure conditions. HPJA is capable of realizing the functionalities of large-area hot jet ignition, fuel activation, and enhanced combustion. The discharge characteristics, fuel activation characteristics, spray characteristics, ignition and assisted combustion characteristics of HPJA was investigated through experimental methods. The discharge power of HPJA initially increases, then decreases, and subsequently increases with the rise in carrier gas flow. Following fuel injection, the discharge power exhibits a similar trend but with an increased magnitude, showing a 21.9 % enhancement when Air = 30 SLM. HPJA has the capability to activate fuel, generating small molecule flammable substances such as H2 and CH4. The flow rates of fuel and nitrogen have a significant impact on the effective cracking rate. As the fuel flow increases, the effective cracking rate decreases. Similarly, with an increase in nitrogen flow, the effective cracking rate initially decreases before increasing again. Upon activation of HPJA excitation, there is a notable reduction in the particle diameter of outlet fuel, leading to a 41.5 % decrease in D32 under WN2 = 40 SLM and Fuel = 0.25–1.25 g/s. Based on the stability of the HPJA outlet's hot jet production, it is categorized into two operational modes: fuel excitation mode and jet evolution mode. As the carrier gas flow increases, the fuel required for HPJA to transition into the jet evolution mode decreases, thereby facilitating rapid ignition functionality. Under Ma = 0.2 and T∗ = 320 K conditions, as P∗ decreases from 107 kPa to 45 kPa, HPJA is more prone to forming a stable hot jet, resulting in an 88.9 % reduction in the fuel needed to enter the jet evolution mode.