The Design and Performance of Two-Dimensional, Curved Diffusers: Part I—Exposition of Method and Part II—Experiment, Evaluation of Method, and Conclusions

Sagi, C. J.; Johnston, J. P.

doi:10.1115/1.3609693

Cited by 28 publications

(3 citation statements)

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“…Numerous investigations had been conducted to provide the design guidelines, such as Kline et al. 12 for conical diffusers, Reneau et al., 13 Sagi and Hohnston 14 for two-dimensional diffusers, Sovern and Klomp 15 and Adkins and Wardle 16 for annular diffusers, and Bhinder and Al-Modafar 17 for straight rectangular diffusers. In these works, the optimal combination of area ratio and diffuser length for appropriate configurations was identified.…”

Section: Introductionmentioning

confidence: 99%

Aerodynamic performance analysis and optimization of a turbine duct with low degree of partial admission

Sui

Zhao

Sun

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part G:

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A partial admission turbine duct with outlet-to-inlet area ratio greater than unity can increase the admission degree of the downstream turbine stage and, thus improve the performance of a multistage turbine with a low partial admission degree. However, the upstream flow structures of ducts, such as secondary flow, especially the circumferential nonuniformities originating from the effect of the partial admission, make the flow in ducts complex. The complexity of the flow has a negative impact on the performance of ducts. In the present investigation, numerical study of the flow behavior within ducts is done to evaluate the effect of the partial admission on the performance of the ducts. The study is carried out with regard to two cases, i.e. which are with the same duct geometry but are at different working conditions to highlight the impact of partial admission on the performance of ducts. Case 1 is used as baseline. It is designed based on circumferential mass-averaged flow conditions at ducts inlet. It causes the circumferential nonuniformities originating from the partial admission to have no impact on the performance of case 1. Case 2, which considers partial admission, is compared with case 1 to know the impact of the partial admission on the performance of ducts, and to give guidelines to design a duct for the partial admission turbines. Since the duct inlet conditions is a result of the interaction between partial admission turbine and duct, a straightforward way to consider the effect of the partial admission is to simulate the flows in ducts and upstream turbines contemporaneously. Comparative results indicate that the mixing of main flow in the admitted channel and the windage fluid from the unadmitted channel occurs at the duct inlet close to the duct circumferential wall. The adverse pressure gradient of case 2 in that region becomes larger than that of case 1. As a result, the flow separates at that region deteriorating the performance of ducts. Based on the simulation results of the previous cases, case 2's circumferential wall surface, which is along the gas swirling direction is shrunk to accelerate the flow and, thereby, overcome the adverse pressure gradient imposed by the effect of the partial admission. The results show that the separation is restrained and the decrease in total pressure loss is 52.9%.

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Section: Introductionmentioning

confidence: 99%

Aerodynamic performance analysis and optimization of a turbine duct with low degree of partial admission

Sui

Zhao

Sun

et al. 2017

Proceedings of the Institution of Mechanical Engineers, Part G:

View full text Add to dashboard Cite

show abstract

“…Study the effect of geometric and operating parameters on the diffuser performance has been of fundamental interest to researchers in the area of fluid mechanics since decades and it continues to grow [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15]. However, the guideline to choose the optimum 3-D turning diffuser has not yet been available reported.…”

Section: Introductionmentioning

confidence: 99%

Effect of Varying Inflow Reynolds Number on Pressure Recovery and Flow Uniformity of 3-D Turning Diffuser

Nordin

Karim

Othman

et al. 2014

AMM

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Various diffuser types characterized by the geometry are introduced in the flow line to recover the energy. A 3-D turning diffuser is a type of diffuser that its cross-section diffuses in all 3 directions of axes, i.e. x, y and z. In terms of applicability, a 3-D turning diffuser offers compactness and more outlet-inlet configurations over a 2-D turning diffuser. However, the flow within a 3-D turning diffuser is expected to be more complex which susceptible to excessive losses. As yet there is no established guideline that can be referred to choose a 3-D turning diffuser with an optimum performance. This paper aims to investigate the effects of varying inflow Reynolds number (Rein) on the performance of 3-D turning diffuser with 90o angle of turn. The outlet pressure recovery (Cp) and flow uniformity (σu) of 3-D turning diffuser with an area ratio (AR = 2.16) and outlet-inlet configurations (W2/W1 = 1.44, X2/X1 = 1.5), operated at inflow Reynolds number of Rein = 5.786E+04 - 1.775E+05 have been experimentally tested. The experimental rig was developed by incorporating several features of low subsonic wind tunnel. This was mainly to produce a perfect fully developed and uniform flow entering diffuser. Particle image velocimetry (PIV) was used to examine the flow quality, and a digital manometer was used to measure the average static pressure of the inlet and outlet of turning diffuser. There is a promising improvement in terms of flow uniformity when a 3-D turning diffuser is used instead of a 2-D turning diffuser with the same AR. An unexpected trend found with a drop of pressure recovery at maximum operating condition of Rein = 1.775E+05 shall require further investigations. The results obtained from this study will be in future used to validate the numerical codes. Upon successful validation, several other configurations will be numerically tested in order to establish the guidelines in the form of mathematical models.

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“…There are various types of diffusers which are commonly classified by their geometries and applications [1][2][3][4][5][6][7][8][9][10][11]. A turning diffuser is a kind of diffuser generally used to join the conduits that not only differ in terms of cross-sectional area but also plane location.…”

Section: Introductionmentioning

confidence: 99%

The Performance of Turning Diffusers at Various Inlet Conditions

Nordin

Karim

Othman

et al. 2013

AMM

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A turning diffuser is often introduced in the flow line to recover the energy losses by converting the kinetic energy to pressure energy. There are two types of turning diffusers, i.e. a 2-D and 3-D diffuser that are commonly defined by their expansion direction. This study aims to investigate the performance of a 2-D and a 3-D turning diffuser with 90o angle of turn and an area ratio, AR=2.16 by means of varying operating conditions. The geometry configurations applied for a 2-D turning diffuser are outlet-inlet configurations, W2/W12-D=2.160, X2/X12-D =1.000 and an inner wall length to an inlet throat width ratio, Lin/W12-D=4.370, whereas for a 3-D turning diffuser, they are W2/W13-D=1.440, X2/X13-D =1.500 and Lin/W13-D=3.970. The operating conditions represented by inflow Reynolds numbers, Rein are varied from 5.786E+04 to 1.775E+05. Particle image velocimetry (PIV) is used to examine the flow quality, and a digital manometer provides the average static pressure at the inlet and outlet of the turning diffuser. A compromise between the maximum permissible pressure recovery and flow uniformity is determined based upon the need. Whenever the flow uniformity being the need it is promising to apply a 3-D turning diffuser for Rein=1.027E+05 - 1.775E+05 and a 2-D turning diffuser for Rein=5.786E+04-6.382E+04. On the other hand, it is viable to opt for a 3-D turning diffuser for Rein=5.786E+04-6.382E+04 and a 2-D turning diffuser for Rein=1.027E+05-1.775E+05 in the case of the outlet pressure recovery being the need. The secondary flow separation takes place prior at 1/2Lin/W1 for a 2-D turning diffuser, whereas approximately at 3/4Lin/W1 for a 3-D turning diffuser.

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The Design and Performance of Two-Dimensional, Curved Diffusers: Part I—Exposition of Method and Part II—Experiment, Evaluation of Method, and Conclusions

Cited by 28 publications

References 0 publications

Aerodynamic performance analysis and optimization of a turbine duct with low degree of partial admission

Aerodynamic performance analysis and optimization of a turbine duct with low degree of partial admission

Effect of Varying Inflow Reynolds Number on Pressure Recovery and Flow Uniformity of 3-D Turning Diffuser

The Performance of Turning Diffusers at Various Inlet Conditions

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