Chinese Engine Development
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Based on the context, they are probably referring to compressor blade(压气机风扇叶片), not turbine blade(涡轮叶片). I remembered Singapore makes carbon fiber based fan blade for GE/RR, the tech should not be too advanced because it is commercialized already. A composite compressor blade could have a larger impact on overall weight reduction due to the total number of blades used, than a composite turbine blade.
The fan blade and compressor blade work under much lower temp than turbine blade (e.g. 400K vs 1800K). A carbon fiber turbine blade is not feasible due to working temperature requirements. In conclusion, it might be a great improvement but it is not the most critical "blade" you normally read from military grade engine articles.
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“这款发动机或已经开始使用空心复合材料叶片技术，采用上述复合材料和工艺的风扇叶片”.
The quoted paragraph might suggest the composite blades are for the fan stage, not the compressor, but if it is for the compressor it’s likely for the low pressure section rather than the high pressure section. Necessary temperature tolerances needed for the compressor blades depends on the particulars stage of the compressor. Later stages in a compressor can get as high as the turbine. What’s novel about the claims isn’t the composite blade itself, but that the blades are supposedly hollow. *Hollow* composite fan blades are not commercial yet.
I can't comment on carbon fiber blades, but regular carbon fiber/composite items are easily made with a hollow core (e.g. honeycomb), because they are basically thousands of thin layers glued together, before cured under pressure.
I actually think it is a misquote since we know the hollow Ti fan blades, as well as composite blades. There is no need to make hollow composite blade to save weight while sacrificing strength because the composites are already much lighter.
I actually think it is a misquote since we know the hollow Ti fan blades, as well as composite blades. There is no need to make hollow composite blade to save weight while sacrificing strength because the composites are already much lighter.
Turbine blades are made hollow for multiple different reasons. Sometimes it’s to save weight, but sometimes it’s to increase heat tolerance.
That is right. That's the reason the article talked about either fan blade and/or compressor blade (in the cold section), not turbine blade.
Isn't the text already crystal clear that it is Fan blade, nothing else?
Blade = 叶片
Fan = 风扇
Turbine = 涡轮
Compressor = 压缩机／压气机
I understand @kurutoga's thinking "why hollow Fan blade", "hollow blade is more meaningful for compressor or turbine", therefor suggesting there may be a misquote of "Fan" in the text.
However, I googled "hollow fan blade" that does return some articles and patents to create hollow fan blade. One patent addressed "improved resistance to buckling without adding wall thickness" . It seems to me that making the fan blade hollow increase its stiffness. I understand that a well designed hollow frame is stronger than a solid piece of same material but being lighter. For a fan blade the hollowing is not about temperature, it is about blade stiffness (air flow) at high rotation speed. High RPM demands lighter blade, high pressure (before and after the fan) demands stiffness.
Another research paper ""
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by78
General
An article from the Chinese Academy of Sciences on increasing compressor efficiency through the application of Coanda Effect, which is achieved by a new compressor vane design.
Original Text:
高推重比和低耗油率是未来高性能航空发动机（如图1所示）的发展趋势。对于压气机部件而言，提高推重比主要有两种途径，一是保证重量不变，提高压气机总压比，二是保证总压比不变，减少压气机级数或单级叶片数，从而降低压气机重量。无论哪种途径，都需要提高压气机的平均级负荷。为了提高负荷，常规的设计方法是提高叶尖速度和气流周向折转角度。若想进一步大幅度提高压气机负荷，受叶片材料强度限制，通过增大叶尖速度提高负荷的方法遭遇瓶颈；而通过增大气流折转角度的高负荷大折转角叶型的附面层流动在高逆压梯度下极易发生分离（如图2所示），从而大大降低叶型的扩压能力和总压损失。因此，必须采用新的流动控制方法，实现高负荷压气机的气动设计。 “康达效应”是流体射流具有绕其附近固体表面流动的趋势的特性，通过康达效应提高环量的翼型被称作环量控制翼型。先进燃气轮机实验室在所长基金和科技委的支持下，创新性地将康达效应应用在高负荷压气机的大折转角静叶上，在叶片尾缘构造康达表面，通过康达喷气抑制吸力面的附面层分离，从而实现高负荷且高效压气机静叶的气动设计。 截至目前，中国科学院工程热物理研究所研究团队在低速环境下完成了大折转角压气机叶栅附面层/角区分离流动特征，大折转角压气机叶栅康达喷气表面优化设计与试验和压气机环境下康达喷气对大折转角静叶吸力面分离的控制机理和效果研究，并都进行了实验验证。实验结果表明：压气机静压升系数和效率均随着康达喷气量的增加而提高，施加1.5%喷气量时，在峰值效率工况下，压气机效率提高2.7%，静压升系数提高1.9。图3给出了施加康达喷气前后对压气机吸力面附面层分离流动的控制效果。 综上所述，可以看出使用康达喷气流动控制方法能够有效控制由静叶叶片数减少带来的大分离流动及相应的流动损失，同时能够有效提升静叶扩压能力，是提高压气机负荷、增加航空发动机推重比一个非常有效的途径。现有的实验研究结果主要集中在低速叶栅和低速压气机实验台上，2019年，研究团队将完成高速叶栅环境下，康达喷气流动控制方法的计算和实验验证工作，全面掌握康达喷气流动控制方法对大分离流动的控制效果和规律。
The Google translation is surprisingly good:
The high thrust-to-weight ratio and low fuel consumption rate are the development trend of future high-performance aeroengines (as shown in Figure 1). For the compressor parts, there are two main ways to increase the thrust-to-weight ratio. One is to ensure the weight is constant, and the total pressure ratio of the compressor is increased. The second is to ensure that the total pressure ratio is constant, and the number of compressor stages or the number of single-stage blades is reduced. Thereby reducing the weight of the compressor. Either way, you need to increase the average load of the compressor. In order to increase the load, the conventional design method is to increase the tip speed and the circumferential direction of the airflow. If you want to further increase the compressor load, the blade material strength is limited, and the method of increasing the load by increasing the tip speed encounters a bottleneck; and the high-load large-angle corner-type boundary layer flow by increasing the airflow folding angle Separation is highly likely to occur under high back pressure gradients (as shown in Figure 2 ), thereby greatly reducing the diffusing capacity and total pressure loss of the airfoil. Therefore, a new flow control method must be adopted to achieve the aerodynamic design of the high-load compressor.
The "Coanda effect" is a property in which a fluid jet has a tendency to flow around a solid surface in its vicinity, and an airfoil that increases the amount of circulation by the Coanda effect is called a loop-controlled airfoil. With the support of the director's fund and the Science and Technology Commission, the advanced gas turbine laboratory innovatively applies the Coanda effect to the large-turn corner vane of the high-load compressor, constructing the Coanda surface at the trailing edge of the blade, and suppressing it through the Coanda jet. The boundary layer of the suction side is separated to achieve aerodynamic design of the high load and high efficiency compressor vane.
Up to now, the research team of the Institute of Engineering Thermophysics of the Chinese Academy of Sciences has completed the separation and flow characteristics of the boundary layer / corner zone of the large-turn corner compressor in a low-speed environment, and optimized the design and test of the surface of the large-turn-angle compressor cascade The control mechanism and effect of the Coanda jet on the separation of the suction surface of the large-turn corner vane are compared with those in the compressor environment. The experimental results show that the static pressure rise coefficient and efficiency of the compressor increase with the increase of the Coanda jet volume. When the 1.5% jet volume is applied , the compressor efficiency is increased by 2.7% and the static pressure rise coefficient is increased under the peak efficiency condition. 1.9 . Figure 3 shows the control effect of the separation and flow of the suction layer on the suction side of the compressor before and after the application of the Coanda jet.
In summary, it can be seen that the use of the Coanda jet flow control method can effectively control the large separation flow caused by the reduction of the number of vane blades and the corresponding flow loss, and at the same time can effectively improve the expansion pressure of the vane, which is to improve the compressor. Load, increase the aero-engine thrust-to-weight ratio is a very effective way. The existing experimental research results are mainly concentrated on the low-speed cascade and low-speed compressor test bench. In 2019 , the research team will complete the calculation and experimental verification of the Coanda jet flow control method under the high-speed cascade environment, and fully grasp the Coanda. The control effect and law of jet flow control method on large separation flow.
Figure 1. A typical turbofan
Figure 2 Separation of the suction surface of the large folding blade
Figure 3 shows the control effect of the Coanda Jet on the separation of the suction layer of the suction side of the blade. Top: static leaf prototype; Bottom: Coanda jet vane applying 1.5% jet.
Original Text:
高推重比和低耗油率是未来高性能航空发动机（如图1所示）的发展趋势。对于压气机部件而言，提高推重比主要有两种途径，一是保证重量不变，提高压气机总压比，二是保证总压比不变，减少压气机级数或单级叶片数，从而降低压气机重量。无论哪种途径，都需要提高压气机的平均级负荷。为了提高负荷，常规的设计方法是提高叶尖速度和气流周向折转角度。若想进一步大幅度提高压气机负荷，受叶片材料强度限制，通过增大叶尖速度提高负荷的方法遭遇瓶颈；而通过增大气流折转角度的高负荷大折转角叶型的附面层流动在高逆压梯度下极易发生分离（如图2所示），从而大大降低叶型的扩压能力和总压损失。因此，必须采用新的流动控制方法，实现高负荷压气机的气动设计。 “康达效应”是流体射流具有绕其附近固体表面流动的趋势的特性，通过康达效应提高环量的翼型被称作环量控制翼型。先进燃气轮机实验室在所长基金和科技委的支持下，创新性地将康达效应应用在高负荷压气机的大折转角静叶上，在叶片尾缘构造康达表面，通过康达喷气抑制吸力面的附面层分离，从而实现高负荷且高效压气机静叶的气动设计。 截至目前，中国科学院工程热物理研究所研究团队在低速环境下完成了大折转角压气机叶栅附面层/角区分离流动特征，大折转角压气机叶栅康达喷气表面优化设计与试验和压气机环境下康达喷气对大折转角静叶吸力面分离的控制机理和效果研究，并都进行了实验验证。实验结果表明：压气机静压升系数和效率均随着康达喷气量的增加而提高，施加1.5%喷气量时，在峰值效率工况下，压气机效率提高2.7%，静压升系数提高1.9。图3给出了施加康达喷气前后对压气机吸力面附面层分离流动的控制效果。 综上所述，可以看出使用康达喷气流动控制方法能够有效控制由静叶叶片数减少带来的大分离流动及相应的流动损失，同时能够有效提升静叶扩压能力，是提高压气机负荷、增加航空发动机推重比一个非常有效的途径。现有的实验研究结果主要集中在低速叶栅和低速压气机实验台上，2019年，研究团队将完成高速叶栅环境下，康达喷气流动控制方法的计算和实验验证工作，全面掌握康达喷气流动控制方法对大分离流动的控制效果和规律。
The Google translation is surprisingly good:
The high thrust-to-weight ratio and low fuel consumption rate are the development trend of future high-performance aeroengines (as shown in Figure 1). For the compressor parts, there are two main ways to increase the thrust-to-weight ratio. One is to ensure the weight is constant, and the total pressure ratio of the compressor is increased. The second is to ensure that the total pressure ratio is constant, and the number of compressor stages or the number of single-stage blades is reduced. Thereby reducing the weight of the compressor. Either way, you need to increase the average load of the compressor. In order to increase the load, the conventional design method is to increase the tip speed and the circumferential direction of the airflow. If you want to further increase the compressor load, the blade material strength is limited, and the method of increasing the load by increasing the tip speed encounters a bottleneck; and the high-load large-angle corner-type boundary layer flow by increasing the airflow folding angle Separation is highly likely to occur under high back pressure gradients (as shown in Figure 2 ), thereby greatly reducing the diffusing capacity and total pressure loss of the airfoil. Therefore, a new flow control method must be adopted to achieve the aerodynamic design of the high-load compressor.
The "Coanda effect" is a property in which a fluid jet has a tendency to flow around a solid surface in its vicinity, and an airfoil that increases the amount of circulation by the Coanda effect is called a loop-controlled airfoil. With the support of the director's fund and the Science and Technology Commission, the advanced gas turbine laboratory innovatively applies the Coanda effect to the large-turn corner vane of the high-load compressor, constructing the Coanda surface at the trailing edge of the blade, and suppressing it through the Coanda jet. The boundary layer of the suction side is separated to achieve aerodynamic design of the high load and high efficiency compressor vane.
Up to now, the research team of the Institute of Engineering Thermophysics of the Chinese Academy of Sciences has completed the separation and flow characteristics of the boundary layer / corner zone of the large-turn corner compressor in a low-speed environment, and optimized the design and test of the surface of the large-turn-angle compressor cascade The control mechanism and effect of the Coanda jet on the separation of the suction surface of the large-turn corner vane are compared with those in the compressor environment. The experimental results show that the static pressure rise coefficient and efficiency of the compressor increase with the increase of the Coanda jet volume. When the 1.5% jet volume is applied , the compressor efficiency is increased by 2.7% and the static pressure rise coefficient is increased under the peak efficiency condition. 1.9 . Figure 3 shows the control effect of the separation and flow of the suction layer on the suction side of the compressor before and after the application of the Coanda jet.
In summary, it can be seen that the use of the Coanda jet flow control method can effectively control the large separation flow caused by the reduction of the number of vane blades and the corresponding flow loss, and at the same time can effectively improve the expansion pressure of the vane, which is to improve the compressor. Load, increase the aero-engine thrust-to-weight ratio is a very effective way. The existing experimental research results are mainly concentrated on the low-speed cascade and low-speed compressor test bench. In 2019 , the research team will complete the calculation and experimental verification of the Coanda jet flow control method under the high-speed cascade environment, and fully grasp the Coanda. The control effect and law of jet flow control method on large separation flow.
Figure 1. A typical turbofan
Figure 2 Separation of the suction surface of the large folding blade
Figure 3 shows the control effect of the Coanda Jet on the separation of the suction layer of the suction side of the blade. Top: static leaf prototype; Bottom: Coanda jet vane applying 1.5% jet.
Is there any info on what the source of the high pressure air mass flow for the coanda jet is? A very similar idea is implemented in the fourth stage fan stator on the AL-31F, which has a slot "short-circuiting" the pressure side of the vane airfoil to the suction side (a jet of high pressure air leaks to the suction side, blowing tangentially over the rear of the suction surface). Which is a long-winded way of saying it's basically an airfoil with a (fixed) !
Illustration from the manual:
Illustration from the manual: