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Figure from:Jet Effects on Coflow Jet Airfoil Performance

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Figure 16

Figure 16

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Fig. 2. Sketch of an airfoil with injection only integrated with a propulsion system.
Fig. 2. Sketch of an airfoil with injection only integrated with a propulsion system.
The momentum equation on the control volume abedefghia gives
The momentum equation on the control volume abedefghia gives
The following conclusions can be drawn from the preceding equations: For a CFJ airfoil, the injection and suction have the same mass flow rate. Hence, the mass conservation gives
The following conclusions can be drawn from the preceding equations: For a CFJ airfoil, the injection and suction have the same mass flow rate. Hence, the mass conservation gives
Equation (21) indicates that, when the Mach number at engine inlet is increased, the ram drag is also increased due to the higher velocity, and the captured area drag is decreased due to the reduced captured area for the jet. The captured area drag is significantly larger than the ram drag if the flow at engine inlet is subsonic. During a flight mission, the flow parameters at the engine inlet may or may not be equal to the freestream parameters. For example, at the starting point to takeoff, the freestream velocity is zero, but the velocity at the engine inlet is far greater than zero to satisfy the engine mass flow requirement to generate the required thrust. During a flight mission, when the mass flow rate required by the engine is equal to the mass flow rate captured by the straight flow tube going into the engine inlet, the freestream flow parameters will be equal to the flow parameters at engine inlet. The drag increase for the airfoil with injection only due to the ram and captured area drag can be also considered as the loss of thrust [8]. A,,, is the captured area to draw the jet mass flow from freestream. The drag due to the term mV; is the ram drag. The drag due to the term p,;Aj,, is the captured area drag. Racad an mace rpancarvatinn
Equation (21) indicates that, when the Mach number at engine inlet is increased, the ram drag is also increased due to the higher velocity, and the captured area drag is decreased due to the reduced captured area for the jet. The captured area drag is significantly larger than the ram drag if the flow at engine inlet is subsonic. During a flight mission, the flow parameters at the engine inlet may or may not be equal to the freestream parameters. For example, at the starting point to takeoff, the freestream velocity is zero, but the velocity at the engine inlet is far greater than zero to satisfy the engine mass flow requirement to generate the required thrust. During a flight mission, when the mass flow rate required by the engine is equal to the mass flow rate captured by the straight flow tube going into the engine inlet, the freestream flow parameters will be equal to the flow parameters at engine inlet. The drag increase for the airfoil with injection only due to the ram and captured area drag can be also considered as the loss of thrust [8]. A,,, is the captured area to draw the jet mass flow from freestream. The drag due to the term mV; is the ram drag. The drag due to the term p,;Aj,, is the captured area drag. Racad an mace rpancarvatinn
Fig. 4 Airfoil section of the baseline airfoil of NACA0025, CF J0025- 065-196 airfoil, and CFJ0025-065-000 airfoil. Figure 5 is the zoomed 2-D mesh near the CFJ0025-065-196 airfoil. The structured mesh is used around the airfoil and unstructured mesh is used in the region away from the airfoil where
Fig. 4 Airfoil section of the baseline airfoil of NACA0025, CF J0025- 065-196 airfoil, and CFJ0025-065-000 airfoil. Figure 5 is the zoomed 2-D mesh near the CFJ0025-065-196 airfoil. The structured mesh is used around the airfoil and unstructured mesh is used in the region away from the airfoil where
Fig. 6 Computed Mach number contours with streamlines for CFJ0025-065-196 airfoil at AoA = 39 deg. Fig. 5 2-D mesh for CFD calculation of the CFJ0025-065-196 airfoil.
Fig. 6 Computed Mach number contours with streamlines for CFJ0025-065-196 airfoil at AoA = 39 deg. Fig. 5 2-D mesh for CFD calculation of the CFJ0025-065-196 airfoil.
Fig. 8 Computed drag coefficient compared with experiment a different AoA.
Fig. 8 Computed drag coefficient compared with experiment a different AoA.
Fig. 7 Computed lift coefficient compared with experiment at different AoA.
Fig. 7 Computed lift coefficient compared with experiment at different AoA.
Fig. 9 Computed momentum coefficient compared with experiment at different AoA.
Fig. 9 Computed momentum coefficient compared with experiment at different AoA.
Fig. 10 3-D mesh for CFD calculation of the CFJ0025-065-196 airfoil with injection and suction ducts.
Fig. 10 3-D mesh for CFD calculation of the CFJ0025-065-196 airfoil with injection and suction ducts.
Fig. 13 Comparison of the computed drag coefficient for the CFJ airfoil and the airfoil with injection only.
Fig. 13 Comparison of the computed drag coefficient for the CFJ airfoil and the airfoil with injection only.
Fig. 12 Comparison of the computed lift coefficient for the CFJ airfoil and the airfoil with injection only.
Fig. 12 Comparison of the computed lift coefficient for the CFJ airfoil and the airfoil with injection only.
Table 1 Comparison of lift coefficient and its breakdowns for the two CFJ airfoils at AoA = 20 deg
Table 1 Comparison of lift coefficient and its breakdowns for the two CFJ airfoils at AoA = 20 deg
Table 3 Comparison of the power required to pump the jet for the two CFJ airfoils at AoA = 20 deg
Table 3 Comparison of the power required to pump the jet for the two CFJ airfoils at AoA = 20 deg
Table 2 Comparison of drag coefficient and its breakdowns for the two CFJ airfoils at AoA = 20 deg
Table 2 Comparison of drag coefficient and its breakdowns for the two CFJ airfoils at AoA = 20 deg