Integration of Co-Flow Jet Airfoil with Quasi-Micro-Compressor for High Efficiency Cruise at Different Mach Numbers

This paper simulates the integration of a 3D Co-Flow Jet (CFJ) airfoil with a quasi-micro-compressor represented by compressor boundary conditions to study the cruise performance with a variation of Mach numbers. The purpose is to understand how the micro-compressor will operate at different Mach numbers in order to design the CFJ airfoil system with high cruise efficiency. The Mach numbers studied are 0.17, 0.25, and 0.46 to represent a range of cruise conditions for electric airplanes. The airfoil is designed for optimum cruise efficiency, meeting the mission requirements from given geometric dimensions. The micro-compressor is designed to satisfy required total pressure ratio and the dimension of the airfoil with a maximized mass flow rate. At Mach numbers 0.17 and 0.25, micro-compressor design G8A has a low design total pressure ratio of 1.04, while Mach number 0.46 requires a micro-compressor design G5 with a higher design total pressure ratio of 1.17 to compensate for the larger boundary layer loss of the airfoil. CFJ injection and suction ducts are designed with minimum total pressure loss to achieve the high efficiency operating region in the compressor map. The ducts connecting the micro-compressors with the CFJ airfoil have a circular shape at the interface of the micro-compressor and transition to rectangle slots at the airfoil. Design iteration of the ducts is an important step in the integration of CFJ airfoil and micro-compressor by matching the mass flow rate and compressor total pressure ratio to the high efficiency operating line. The micro-compressor outlet is simulated with a swirl profile provided by each of the two compressor designs. The micro-compressor design is only conducted once and is not in the iteration process to save the design cycle. The micro-compressor is thus a quasi-micro-compressor. The simulation of each Mach number is for cruise condition at low angle of attack 5° with a range of 0° to 15°. The results show that by integrating the designs of micro-compressor and CFJ airfoil through duct design, a high efficiency operating line can be achieved with efficiency of about 76% to 82% for Mach number 0.17, 79% to 85% for Mach number 0.25, and 73% to 78% for Mach number 0.46. The study demonstrates that CFJ airfoil design integration with the micro-compressor allows the CFJ aircraft to cruise at a high efficiency operating range of the compressor for a range of Mach numbers.