Experimental and Numerical Study of Orifice Discharge Coefficients in High-Speed Rotating Disks

Wittig, Sigmar; Kim, S.; Jakoby, Ralf; Weißert, I.

doi:10.1115/1.2836655

Cited by 23 publications

(13 citation statements)

References 10 publications

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“…Research on a rotating orifice showed that the effects of rotational speed and preswirled flow on the discharge coefficient are important. For example, Wittig, Kim, Jakoby, and Weibert (1996) measured the discharge coefficient of an orifice under different rotational speeds. The results showed that the discharge coefficient decreases with increasing rotational speed, and the value at the maximum rotational speed (1000 rpm) is only 66% of the result at 0 rpm for a basic orifice geometry.…”

Section: Introductionmentioning

confidence: 99%

A mathematical model for predicting the pressure drop in a rotating cavity with a tubed vortex reducer

Song

Yan

Mao

et al. 2019

Engineering Applications of Computational Fluid Mechanics

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The flow characteristics of a tubed vortex reducer, which was used to reduce the pressure drop in an aeroengine air bleed system, were studied in this paper. Accurate prediction of the pressure drop in a rotating cavity with tubed vortex reducer installed is important, but the complex flow structure results in complicated local loss characteristic at the tube entrance, which is difficult to estimate. In this paper, a mathematical model for predicting the pressure drop in a rotating cavity with a tubed vortex reducer was established. For the first time, the effect of the local loss at the tube entrance under rotating conditions was considered, and a method of introducing the local loss factor was established based on a research method applied in traditional rotating orifices. Furthermore, the flow characteristics and the distribution of the static pressure in the tubed vortex reducer cavity were studied by the CFD method and experimental tests, and the pressure information inside the tubed vortex reducer was obtained by detailed experimental testing. This study reveals that the local loss characteristics at the tube entrance are mainly influenced by the incident angle; the closer the incident angle is to 0, the greater the speed coefficient is. The pressure drop at the tube entrance is important and represents approximately 10% of the total pressure drop. The mathematical model shows good accuracy for calculating the pressure drop, with an average error of approximately 2% compared to the experimental data.

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Section: Introductionmentioning

confidence: 99%

A mathematical model for predicting the pressure drop in a rotating cavity with a tubed vortex reducer

Song

Yan

Mao

et al. 2019

Engineering Applications of Computational Fluid Mechanics

View full text Add to dashboard Cite

show abstract

“…Wittig et al [10] used the energy equation to formulate the discharge coef cient with assumptions of compressible, isentropic, and steady ow of a perfect gas. The discharge coef cient is written as…”

Section: Discussionmentioning

confidence: 99%

“…Wittig et al [10] used the discharge coef cient derived from energy conservation, entropy and ideal gas relations. Laser-Doppler Velocimeter, LDV, was used to measure the local ow velocities, and the data were compared with the numerical analysis of a commercial nite volume code (TASC ow3D).…”

Section: Introductionmentioning

confidence: 99%

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An investigation into the flow within inclined rotating orifices and the influence of incidence angle on the discharge coefficient

Indris

Pullen

Barnes

2004

Proceedings of the Institution of Mechanical Engineers, Part A:

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In many engineering machines, it is necessary to pass fluid, usually air, through rotating surfaces, such as a disc or drum. This is achieved by perforating the disc with a series of holes arranged on a pitch circle. It is vital for the machine designer to know the pressure ratio required to pass a desired mass flow rate. This characteristic is defined by determination of the discharge coefficient as a function of various parameters. Until recently, the literature describing this problem was small and covered a few particular cases. More articles are appearing and this present study seeks to add to the current level of knowledge by addressing the effect of the inclinations of the holes to the tangential direction. A rig was designed and built to perform the experiments and the data were compared with the numerical analysis performed by proprietary software STAR-CD. The results indicate that the discharge coefficient is highly affected by the rotational speed and that orientating the orifices at an appropriate angle of inclination enables the discharge coefficient to be maximized. Most of the studies in the past used the ratio of tangential speed and the ideal axial velocity to represent the discharge coefficient, but it has been revealed in this paper that incidence angle is more appropriate in correlating the effect of orifice inclination and rotation on the discharge coefficient. Both the experimental and numerical results confirm that the incidence angle plays a major role in dictating the discharge coefficient of the rotating orifices.

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“…The main limitation of the study divulged in this article is that the rotation of the system is disregarded. At steady-state conditions, the effect of rotation in the performance of the SAS has been described in the literature for cavities [1,8,9], connecting tubes [20], and discharge holes [21,22]. In essence, the flow through a rotating cavity will take the form of a central region that contains the core flow that has a zero radial velocity surrounded by boundary layers attached to the rotating discs through which all the through flow takes place.…”

Section: Current Model Capabilitymentioning

confidence: 99%

Time accurate modelling of the secondary air system response to rapid transients

Gallar

Calcagni

Llorens

et al. 2011

Proceedings of the Institution of Mechanical Engineers, Part G:

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The amount of air drawn by the secondary air system (SAS) from the main gas path, although necessary, impairs the engine performance because it does not contribute to engine thrust. In order to quantify and minimize this pernicious effect, the usual practice is to model the air system with one-dimensional network solvers where the net nodes represent the various components of the system. For usual engine transients, it is sufficient to analyse the system performance with a quasi-steady approach because the time constant of the air system is two orders of magnitude smaller than the turbomachinery characteristic time. Nonetheless, the rapid changes that occur during certain transient or failure scenarios – particularly shaft failure events – call for a different approach to calculate the air system performance and the fluctuations of the turbomachinery endloads. However, there is no such approach available in the open literature to predict the transient response of the system. For steady-state conditions, the differential equations that govern the fluid evolution are not time discretized and thus can be solved in a relatively straightforward fashion. Moreover, unlike during transients, the flow is not supposed to reach sonic conditions anywhere within the network and, more importantly, flow reversal is not expected to occur. The aim of this study is to develop a model for gas turbine SAS dynamics capable of tackling the sudden changes in the flow properties that occur within the system in the rapid transient scenarios. The whole system is initially broken down into a series of chambers of a finite volume connected by pipes that are initially modelled in isolation and then interconnected. The single-component models and their assembly are successfully validated against numerical and experimental data. The resultant modular tool constitutes a baseline into which further improvements and modifications can be integrated in subsequent works. The usefulness of the computational tool is demonstrated through the analysis of the flow evolution within the SAS and the subsequent turbine endload during a shaft failure event.

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Experimental and Numerical Study of Orifice Discharge Coefficients in High-Speed Rotating Disks

Cited by 23 publications

References 10 publications

A mathematical model for predicting the pressure drop in a rotating cavity with a tubed vortex reducer

A mathematical model for predicting the pressure drop in a rotating cavity with a tubed vortex reducer

An investigation into the flow within inclined rotating orifices and the influence of incidence angle on the discharge coefficient

Time accurate modelling of the secondary air system response to rapid transients

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