# Toward the Utilization of 3D Blading in the Cantilevered Stator from Highly Loaded Compressors
## 4 Application of 3D Blading in a Cantilevered Stator
### Discussion of the Experimental Results  
#### 4.2.1 Effect of 3D Blading on the Aerodynamic Performance  
To start, the overall aerodynamic performance of the compressor stage is compared, as shown in Figure 30. Results highlight that the 3D blading on the cantilevered stator could significantly improve the performance of the compressor stage at small mass flow conditions; at the near stall condition (P4), the total pressure rise coefficient and the efficiency are increased by 3% and 2%, respectively. However, as the operating point moves to the right, the 3D blading will start losing its advantage, and the stage efficiency at \(\varphi>0.51\) will even drop by 0.7%. As only stator blades have been changed, Figure 31 shows the loss characteristics of the cantilevered stators, in which the CFD results are also plotted to present the deviation between the experiment result and the CFD result. Figure 31 indicates the CFD results have high reference value, so the above numerical analysis results are credible. Figure 29: The radial distribution of mass flow coefficient and loss under different operating conditions: (**a**) outlet mass flow coefficient; (**b**) total pressure loss. Turning to the stator blade row, Figure 32a presents the variation of the stator total pressure loss coefficient with the stage mass flow coefficient. In comparison with the datum scheme, the total pressure loss of the 3D cantilevered stator is reduced significantly; the absolute reduction reaches 0.035 at the near-stall point (P4), or 20.5%. However, the loss of the cantilevered stator will increase slightly at higher mass flow conditions; the maximum increment is 0.008 at \(\varphi=0.53\), which is acceptable in consideration of its advantage under other conditions. Additionally, the variation of the stator loss coincides with the trend on the stage level, thus implying that the variation of compressor stage performance in Figure 30 is attributed mainly to the 3D bladed stator. In order to further quantify the impact of 3D blading on different regions of the cantilevered stator, the total loss is decomposed along the blade span, as shown in Figure 32b-d. The blade is classified into three regions according to the mass flow, i.e., the hub region (0\(\sim\)25% total mass flow), the middle region (25\(\sim\)75% total mass flow), and the tip region (75\(\sim\)100% total mass flow). Results show that the loss reduction of the 3D stator stems mainly from the hub and midspan regions, which is consistent with the weakening of corner flow separation in these areas. Moreover, the utilization of the forward sweep turns out to improve the tip region over the whole operating range, which signifies the necessity of balancing radial flow in the design process. Figure 31: Comparison of loss characteristics of the cantilevered stators between experiment and CFD. Figure 30: Comparison of performance characteristics of the compressor stage: (**a**) total pressure rise coefficient; (**b**) efficiency. The radial distribution of the mass flow coefficient for the cantilevered stator is illustrated in Figure 33. Results show that the 3D blading barely influences the mass flow distribution at the stator inlet, whereas it could improve the throughflow capacity at the hub region over a wide operating range. The distribution of mass flow coefficient at the stator outlet exhibits a similar pattern to that in Figure 29, which proves the accuracy of the numerical simulation. On the other hand, the mass flow coefficient in the lower span areas of the stator outlet sees a remarkable increment at P2-P4 conditions, implying the flow capacity near the endwall is enhanced via the combination of the forward sweep and dihedral. It should be noted that at the P1 condition, the mass flow coefficient of a 10-40% span is reduced for the 3D blading scheme, which indicates the flow capacity is weakened in these regions. The mass flow at the midspan areas is first increased and then decreased as the operating point moves from P1 to P4, owing to the redistribution of radial flow.