Effects of hot streak indexing in a 1-1/2 stage turbine

Takahashi, R. K.; Ni, Ron-Ho; Sharma, Om P.; Staubach, J. B.

doi:10.2514/6.1996-2796

Cited by 8 publications

(2 citation statements)

References 3 publications

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“…Similar findings have been reported in several numerical studies using two-dimensional [11,12] and threedimensional [13] unsteady solvers. Other studies have shown that circumferentially clocking of the hot streak with the vane can reduce the degree of hot gas segregation on the HPT rotor pressure surface (Takahashi et al [14], Dorney and Gundy-Burlet [15]). Note that the additional secondary flows described earlier would be expected to have the strongest effect on the rotor pressure surface due to preferential migration (dashed lines in Fig.…”

Section: Introductionmentioning

confidence: 99%

Hot Streak and Vane Coolant Migration in a Downstream Rotor

Ong¹,

Miller

2012

Journal of Turbomachinery

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This paper describes a method of improving the cooling of the hub region of highpressure turbine (HPT) rotor by making better use of the unsteady coolant flows originating from the upstream vane. The study was performed computationally on an engine HPT stage with representative inlet hot streak and vane coolant conditions. An experimental validation study of hot streak migration was undertaken on two low-speed test facilities. The unsteady mechanisms that transport hot and cold fluid within the rotor hub region are first examined. It was found that vortex-blade interaction dominated the unsteady transport of hot and cold fluid in the rotor hub region. This resulted in the transport of hot fluid onto the rotor hub and pressure surface, causing a peak in the surface gas temperatures. The vane film coolant was found to have only a limited effect in cooling this region. A new cooling configuration was thus examined which exploits the unsteadiness in rotor hub to aid transport of coolant towards regions of high rotor surface temperatures. The new coolant was introduced from a slot upstream of the vane. This resulted in the feed of slot coolant at a different phase and location relative to the vane film coolant within the rotor. The slot coolant was entrained into the unsteady rotor secondary flows and transported towards the rotor hub-pressure surface region. The slot coolant reduced the peak time-averaged rotor temperatures by a similar amount as the vane film coolant despite having only a sixth of the coolant mass flow.

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Section: Introductionmentioning

confidence: 99%

Hot Streak and Vane Coolant Migration in a Downstream Rotor

Ong¹,

Miller

2012

Journal of Turbomachinery

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“…For this reason, the method of using hot streak clocking effect is proposed. Takahashi et al (1996) and Gundy-Burlet & Dorney (1997) showed that "clocking" the hot streaks so that it is positioned at the leading edge of the vane results in a diminishing of the effect of the hot streak on the downstream rotor. This was attributed to the deceleration and increased mixing of the hot streak as it interacted with wake of the vane.…”

Section: Hot Streaksmentioning

confidence: 99%

Unsteady Flows in Turbines

Qi¹,

Zou²

2012

Noise Control, Reduction and Cancellation Solutions in Engineering

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Assessing Convergence in Predictions of Periodic-Unsteady Flowfields

Clark

Grover

2006

Journal of Turbomachinery

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Predictions of time-resolved flowfields are now commonplace within the gas-turbine industry, and the results of such simulations are often used to make design decisions during the development of new products. Hence it is necessary for design engineers to have a robust method to determine the level of convergence in design predictions. Here we report on a method developed to determine the level of convergence in a predicted flowfield that is characterized by periodic unsteadiness. The method relies on fundamental concepts from digital signal processing including the discrete Fourier transform, cross correlation, and Parseval’s theorem. Often in predictions of vane–blade interaction in turbomachines, the period of the unsteady fluctuations is expected. In this method, the development of time-mean quantities, Fourier components (both magnitude and phase), cross correlations, and integrated signal power are tracked at locations of interest from one period to the next as the solution progresses. Each of these separate quantities yields some relative measure of convergence that is subsequently processed to form a fuzzy set. Thus the overall level of convergence in the solution is given by the intersection of these sets. Examples of the application of this technique to several predictions of unsteady flows from two separate solvers are given. These include a prediction of hot-streak migration as well as more typical cases. It is shown that the method yields a robust determination of convergence. Also, the results of the technique can guide further analysis and∕or post-processing of the flowfield. Finally, the method is useful for the detection of inherent unsteadiness in the flowfield, and as such it can be used to prevent design escapes.

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Effects of hot streak indexing in a 1-1/2 stage turbine

Cited by 8 publications

References 3 publications

Hot Streak and Vane Coolant Migration in a Downstream Rotor

Hot Streak and Vane Coolant Migration in a Downstream Rotor

Unsteady Flows in Turbines

Assessing Convergence in Predictions of Periodic-Unsteady Flowfields

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