Search

The high-quality flow field of an aeroengine ground test cell is the basis for accurate and reliable engine testing and obtaining relevant performance data. In this study for a U-shaped ground test cell, first, the similarity dimension analysis between the original model and the 1∶10 scaled model is conducted to verify the accuracy of the numerical simulation of the scaled model. Then, the parametric numerical simulation method is used to study the effects of the augmentor's diameter and the distance between the engine jail nozzle and the augmentor inlet on the aerodynamic flow field of the ground test cell for the 1∶10 scaled model. The results show that if the diameter of the augmentor tube is too large or too small, the flow rate of the bypass airflow in the augmenter will decrease; thus, the average temperature of the exit section will increase. At the same time, the change of airflow exhaust speed in the blast basket can effectively affect the uniformity of airflow in the silencing tower. With the increase of distances between the engine jail nozzle and the augmentor inlet, the ejection effect of the engine tail jet enhances, but the exhaust velocity in the blast basket decreases; accordingly, the quality of the flow field in the silencer tower significantly deteriorates with the tendency of the vortex centers on both sides of the pipe moving upward. In Case4 , the airflow velocity at the front chamber inlet of the test workshop is significantly higher than that of the baseline model, Case0 , and the ejection ratio increases by 19.4%. [ABSTRACT FROM AUTHOR]

The air flow'field of a foreign fiber separator is simulated numerically. Effects of design parameters such as the nozzle diameter and entrance width of the noil box on the air velocity along nozzle axis, turbulence intensity, and jet deflection distance are studied. Larger nozzle diameters and larger entrance widths of the noil box are advantageous to the elimination of foreign fibers. The results provide a theoretical basis for the design of foreign fiber separators. [ABSTRACT FROM AUTHOR]

The current study highlights the superiority of nozzles with forwarding airflow to produce the commingled yarns for thermoplastic composite applications. A new cost-effective nozzle that can produce good quality commingled yarns at low air pressure is introduced. 3D CFD simulation and experimental studies are conducted to investigate the effect of aerodynamics of three different cylindrical nozzle configurations (CONF) on the commingling process efficiency. Nozzle CONF I and II work on backwards airflow principles among these configures, while CONF III functions with forwarding airflow. Commingling process efficiency of nozzle designs is analysed in terms of vorticity magnitude, turbulence kinetic energy, turbulence intensity and radial velocity values obtained from the simulation study. Additionally, the structure of hybrid yarns is qualitatively analysed to support the simulation study. The study concludes that nozzle CONF I and III holds the excellent potential of mixing both reinforcement and matrix filaments across the yarn structure. In addition, these nozzles can form stable nips in the yarn structure and make the textile preforming effortless. Nozzle CONF III offers better yarn quality parameters over other nozzles at low processing pressure. [ABSTRACT FROM AUTHOR]

The flow of products through the aft-end of a detonation combustor is intrinsically unsteady, ultimately resulting in periodic and nonuniform flow parameters at the exit plane of a rotating detonation combustor. Therefore, the integrated design of the nozzle and combustion chamber is an important challenge in rotating detonation engines (RDEs). This paper describes a thorough three-dimensional numerical simulation of a hydrogen–air rotating detonation combustor with/without an aerospike nozzle and investigates the nozzle flow without a combustor. The simulation results allow us to analyze the coupling characteristics of the rotating detonation combustor and the aerospike nozzle. The new features of the shock wave dynamics and expansion characteristics in the nozzle with/without an integrated RDE combustor are compared. For the same rotating detonation combustor exit, the propagation mode of the detonation wave and backpressure in the RDE combustor exit are affected by the aerospike nozzle. The intensity of the shock wave and the angle with respect to the direction of the air flow are lower with the aerospike nozzle than in the nozzleless model, which is consistent with the effect of backpressure increase on the shock dynamics. Regardless of whether the nozzle is connected to the combustor, the nozzle affects the dynamic alternation of the design point state to over-expansion and under-expansion along the circumferential direction. The shock wave intensity and total pressure recovery inside the nozzle with the combustor are slightly stronger than those in the nozzle without the combustor. Consequently, the thrust and total pressure recovery of the nozzle integrated with the RDE combustor are enhanced by 7% and 5.6%, respectively. Thus, decoupling the nozzle from the rotating detonation combustor is feasible for testing the design performance of the unsteady nozzle. [ABSTRACT FROM AUTHOR]