By using steady and transient methods, the total heat fluxes and the distributions of the heat flux were measured experimentally for an argon DC laminar plasma jet impinging normally on a flat plate at atmospheric pre...By using steady and transient methods, the total heat fluxes and the distributions of the heat flux were measured experimentally for an argon DC laminar plasma jet impinging normally on a flat plate at atmospheric pressure. Results show that the total heat fluxes measured with a steady method are a little bit higher than those with a transient method. Numerical simulation work was executed to compare with the experimental results.展开更多
A transient thickness distribution measured with a high temporal resolution is elemental for exploring the flow characteristics and mechanism of a liquid film formed by an impinging jet.Therefore,this paper develops a...A transient thickness distribution measured with a high temporal resolution is elemental for exploring the flow characteristics and mechanism of a liquid film formed by an impinging jet.Therefore,this paper develops a high-speed Light-Emitting Diode-Induced Fluorescence(LEDIF)system based on the brightness measured directly above the liquid film.An Ultraviolet(UV)LED lamp is used to provide sufficient and continuous excitation light.Then,a system performance analysis proves that the system can continuously measure the global film thickness at a high acquisition frequency of 5000 Hz when the dye concentration is 200 mg/L.The influence of the irregularity of the excitation intensity,including the spatial non-uniformity,temporal instability,and long-term instability,on the measurement uncertainty is analyzed in detail.The analysis indicates that the system has an acceptable uncertainty of 10%.Compared with theoretical results,experimental results verify that the LEDIF system can accurately measure the global thickness of a liquid film formed by a water jet obliquely impinging onto a plate.An experimental investigation of the radial section of the raised zone demonstrates that the radial section changes from a sewing needle to an oval when the azimuth angle increases from 10°to 90°.Meanwhile,the dynamic contact angle exponentially decreases from 41.4°to 30.1°.A dynamic analysis of surface waves shows that the measured wave velocity decreases from 12 m/s to 1 m/s and the dominant frequency decreases from 1000 Hz to 10 Hz along the flow direction.展开更多
Nowadays, carbon fiber composite material is becoming more and more popular in aero engine industry due to its high specific strength and stiffness. Laminate carbon fiber composite material is widely used to manufactu...Nowadays, carbon fiber composite material is becoming more and more popular in aero engine industry due to its high specific strength and stiffness. Laminate carbon fiber composite material is widely used to manufacture the high load wide chord fan blade, containment casing, etc. The aeroelastic behavior of composite product is critical for the optimization of the product design and manufacturing. In order to explore its aeroelastic property, this paper discusses the coupled simulation of aerodynamic excitation applied on laminate composite material plate. Mechanical behavior of composite material plate is different from that of isotropic material plate such as metal plate, because it is anisotropy and has relative high mechanical damping due to resin between plies. These plates to be studied are designed using 4 different layup configurations which follow the design methods for composite fan blade. The numerical simulation of force response analysis mainly uses single frequency mechanical force input to simulate the electromagnetic shakers or other actuators, which could transmit mechanical force to the test parts. Meanwhile, pulsed air excitation is another way to "shake" the test parts. This excitation method induces aero damping into the test part and simulates the unsteady flow in aero engine, which could cause aeroelastic problems, such as flutter, forced response and non-synchronous vibration(NSV). In this study, numerical simulation using coupled method is conducted to explore the characteristics of laminate composite plates and the property of aerodynamic excitation force generated by pulsed air jet device. Modal analysis of composite plate shows that different ply stacking sequences have a significant impact on the plate vibration characteristics. Air pulse frequency and amplitude in flow field analysis are calibrated by hot wire anemometer results. As the air pulse frequency and amplitude are varied, incident angle of flow and layup configurations of plate can be analyzed in details by the simulations. Through the comparisons of all these factors, air pulse excitation property and the aeroelastic behavior of composite material plate are estimated. It would provide a possible way to guide the next-step experimental work with the pulsed air rig. The new composite fan blade design can be evaluated through the process.展开更多
基金he National Natural Science Foundation of China under the grant No. 59836220 and 19975064and endowed with President's Foundati
文摘By using steady and transient methods, the total heat fluxes and the distributions of the heat flux were measured experimentally for an argon DC laminar plasma jet impinging normally on a flat plate at atmospheric pressure. Results show that the total heat fluxes measured with a steady method are a little bit higher than those with a transient method. Numerical simulation work was executed to compare with the experimental results.
基金supported by the Provincial or Ministerial Level Project,China。
文摘A transient thickness distribution measured with a high temporal resolution is elemental for exploring the flow characteristics and mechanism of a liquid film formed by an impinging jet.Therefore,this paper develops a high-speed Light-Emitting Diode-Induced Fluorescence(LEDIF)system based on the brightness measured directly above the liquid film.An Ultraviolet(UV)LED lamp is used to provide sufficient and continuous excitation light.Then,a system performance analysis proves that the system can continuously measure the global film thickness at a high acquisition frequency of 5000 Hz when the dye concentration is 200 mg/L.The influence of the irregularity of the excitation intensity,including the spatial non-uniformity,temporal instability,and long-term instability,on the measurement uncertainty is analyzed in detail.The analysis indicates that the system has an acceptable uncertainty of 10%.Compared with theoretical results,experimental results verify that the LEDIF system can accurately measure the global thickness of a liquid film formed by a water jet obliquely impinging onto a plate.An experimental investigation of the radial section of the raised zone demonstrates that the radial section changes from a sewing needle to an oval when the azimuth angle increases from 10°to 90°.Meanwhile,the dynamic contact angle exponentially decreases from 41.4°to 30.1°.A dynamic analysis of surface waves shows that the measured wave velocity decreases from 12 m/s to 1 m/s and the dominant frequency decreases from 1000 Hz to 10 Hz along the flow direction.
文摘Nowadays, carbon fiber composite material is becoming more and more popular in aero engine industry due to its high specific strength and stiffness. Laminate carbon fiber composite material is widely used to manufacture the high load wide chord fan blade, containment casing, etc. The aeroelastic behavior of composite product is critical for the optimization of the product design and manufacturing. In order to explore its aeroelastic property, this paper discusses the coupled simulation of aerodynamic excitation applied on laminate composite material plate. Mechanical behavior of composite material plate is different from that of isotropic material plate such as metal plate, because it is anisotropy and has relative high mechanical damping due to resin between plies. These plates to be studied are designed using 4 different layup configurations which follow the design methods for composite fan blade. The numerical simulation of force response analysis mainly uses single frequency mechanical force input to simulate the electromagnetic shakers or other actuators, which could transmit mechanical force to the test parts. Meanwhile, pulsed air excitation is another way to "shake" the test parts. This excitation method induces aero damping into the test part and simulates the unsteady flow in aero engine, which could cause aeroelastic problems, such as flutter, forced response and non-synchronous vibration(NSV). In this study, numerical simulation using coupled method is conducted to explore the characteristics of laminate composite plates and the property of aerodynamic excitation force generated by pulsed air jet device. Modal analysis of composite plate shows that different ply stacking sequences have a significant impact on the plate vibration characteristics. Air pulse frequency and amplitude in flow field analysis are calibrated by hot wire anemometer results. As the air pulse frequency and amplitude are varied, incident angle of flow and layup configurations of plate can be analyzed in details by the simulations. Through the comparisons of all these factors, air pulse excitation property and the aeroelastic behavior of composite material plate are estimated. It would provide a possible way to guide the next-step experimental work with the pulsed air rig. The new composite fan blade design can be evaluated through the process.
