scholarly journals Дифференциальные характеристики поля течения перерасширенной газовой струи в окрестности кромки сопла

2019 ◽  
Vol 89 (4) ◽  
pp. 483
Author(s):  
М.В. Чернышов ◽  
Л.Г. Гвоздева

AbstractA parametric study of the features of the flow field of a plane and axisymmetric overexpanded ideal gas jet in the vicinity of the nozzle edge has been conducted over the entire theoretically admissible range of determining parameters (nozzle divergence angles, exhaust Mach numbers, jet incalculabilities, and gas adiabat indicators). The exhaust parameters that correspond to the extremes of the differential characteristics of a shockwave falling (descending) from the edge and the flow field behind it have been revealed. A significant difference in the character of changes in the characteristics of the shockwave and the flow field behind it depending on the type of symmetry of the gas jet has been found and studied.

2011 ◽  
Vol 18 (4) ◽  
pp. 11-18 ◽  
Author(s):  
Jun-guo Li ◽  
Ya-nan Zeng ◽  
Jian-qiang Wang ◽  
Zhi-jie Han
Keyword(s):  
Gas Jet ◽  

1986 ◽  
Vol 108 (2) ◽  
pp. 269-274
Author(s):  
R. G. Williamson ◽  
S. H. Moustapha ◽  
J. P. Huot

Two nozzle designs, involving the same low aspect ratio, high turning angle vanes, and differing in outer wall contour, were tested over a range of exit Mach numbers up to supersonic values. The experiments were conducted on a large-scale, full annular configuration with and without a representative rotor downstream. Nozzle performance was found to be significantly affected by rotor operation, the influence depending on the detailed characteristics of the nozzle flow field, as well as on the design and operation of the rotor itself. It is suggested that performance evaluation of low aspect ratio nozzles of high turning angle may require appropriate testing with a rotor.


2010 ◽  
Vol 132 (3) ◽  
Author(s):  
Duccio Bonaiuti ◽  
Mehrdad Zangeneh ◽  
Reima Aartojarvi ◽  
Jonas Eriksson

The present paper describes the parametric design of a mixed-flow water-jet pump. The pump impeller and diffuser geometries were parameterized by means of an inverse design method, while CFD analyses were performed to assess the hydrodynamic and suction performance of the different design configurations that were investigated. An initial pump design was first generated and used as baseline for the parametric study. The effect of several design parameters was then analyzed in order to determine their effect on the pump performance. The use of a blade parameterization, based on inverse design, led to a major advantage in this study, because the three-dimensional blade shape is described by means of hydrodynamic parameters, such as blade loading, which has a direct impact on the hydrodynamic flow field. On the basis of this study, an optimal configuration was designed with the aim of maximizing the pump suction performance, while at the same time, guaranteeing a high level of hydrodynamic efficiency, together with the required mechanical and vibrational constraints. The final design was experimentally tested, and the good agreement between numerical predictions and experimental results validated the design process. This paper highlights the contrasting requirements in the pump design in order to achieve high hydrodynamic efficiency or good cavitation performance. The parametric study allowed us to determine design guidelines in order to find the optimal compromise in the pump design, in cases where both a high level of efficiency and suction performance must simultaneously be achieved. The design know-how developed in this study is based on flow field analyses and on hydrodynamic design parameters. It has therefore a general validity and can be used for similar design applications.


2018 ◽  
Vol 2018 ◽  
pp. 1-9
Author(s):  
Fangyuan Lou ◽  
John Charles Fabian ◽  
Nicole Leanne Key

This paper investigates the aerodynamics of a transonic impeller using static pressure measurements. The impeller is a high-speed, high-pressure-ratio wheel used in small gas turbine engines. The experiment was conducted on the single stage centrifugal compressor facility in the compressor research laboratory at Purdue University. Data were acquired from choke to near-surge at four different corrected speeds (Nc) from 80% to 100% design speed, which covers both subsonic and supersonic inlet conditions. Details of the impeller flow field are discussed using data acquired from both steady and time-resolved static pressure measurements along the impeller shroud. The flow field is compared at different loading conditions, from subsonic to supersonic inlet conditions. The impeller performance was strongly dependent on the inducer, where the majority of relative diffusion occurs. The inducer diffuses flow more efficiently for inlet tip relative Mach numbers close to unity, and the performance diminishes at other Mach numbers. Shock waves emerging upstream of the impeller leading edge were observed from 90% to 100% corrected speed, and they move towards the impeller trailing edge as the inlet tip relative Mach number increases. There is no shock wave present in the inducer at 80% corrected speed. However, a high-loss region near the inducer throat was observed at 80% corrected speed resulting in a lower impeller efficiency at subsonic inlet conditions.


Author(s):  
S. O. Kraus ◽  
R. Flack ◽  
A. Habsieger ◽  
G. T. Gillies ◽  
K. Dullenkopf

The unsteady flow field due to blade passing at the pump/turbine interface of a torque converter was studied. The current geometry is wide and has a large outer to inner radius ratio. A laser velocimeter was used to measure the periodic velocity components at four operating conditions determined by the speed ratios between the turbine and pump of 0.065 (near stall), 0.600, 0.800, and 0.875 (coupling point). The flow fields at the pump exit and turbine inlet planes were visualized and are presented. Using instantaneous pump and turbine blade positions with the velocity data, animations (“slow-motion movies”) are generated to effectively visualize and understand the unsteady behavior. The turbine inlet flow was markedly periodic due to the exiting jet/wake from the upstream pump passage; however, the pump exit flow field showed little dependence on the turbine blade positions. The highest unsteadiness was seen for the highest speed ratios. Four “shots” from the sequences of one cycle for all speed ratios and each plane are presented herein. The results are also compared to unsteady results for a previously examined torque converter with a small radius ratio to determine the effect of parametric geometric changes on the flow field. Generally, the unsteady velocity fields show no significant difference for the two geometries — the trends are the same.


Author(s):  
Donald Katze

The approximate blowdown/jet impingement force resulting from the rupture of a pipe into a low back pressure receiver is presented. The pipe fluid is an ideal gas flowing under isentropic conditions. Initial flow with Mach numbers up to 0.25 is considered. Solution of the governing thermal hydraulic equations is by the method of characteristics and application is by a wave diagram.


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