Experimental and numerical investigation of the transition progress of strut-induced wakes in the supersonic flows

This study focuses on the effects of three groove tip structures (full rib groove tip, partial rib tip on the suction side, and partial rib tip on the pressure side) on tip leakage flow, aerodynamic characteristics of a cascade, and heat transfer in a gas turbine blade. The groove’s width B = 1.6 mm, while the tip clearance is τ = 1.2 mm. Results of the flow parameters, fluid flow, and heat transfer in the recessed channel are discussed. The results show that all ribbed tips obtain more uniform outlet flow angle distribution and higher aerodynamic performance than the plane tips. The total aerodynamic pressure loss of the ribbed tips on the pressure side is the same as that of complete ribbed tips. The evolution mechanisms are different, although both can improve the turbine efficiency. Although the partial rib tip on the pressure side weakens the mixing of the channel vortex and leakage vortex near the trailing edge and has the best control effect on the leakage vortex, the lack of the suction side rib will make it easier for the low-energy fluid to flow into the gap from the front of the suction side, which is not conducive to reducing the leakage flow inside the gap; the full rib tip not only minimizes the tip relative leakage flow and leakage loss but also increases the channel vortex loss. With the complex vortex system in the groove and the rib blocking effect at the leakage outlet, the suction-side rib tip becomes the tip structure with the best leakage flow control effect under the same clearance, but the leakage vortex loss is the highest.

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“…Steady-state incompressible inviscid fluid flow is controlled by the following equation (Liu et al, 2021):…”

Section: Solution Methodsmentioning

confidence: 99%

Influence of grooved rib tip structure on tip loss and heat transfer in a gas turbine blade

Kong

Zhang

2022

Front. Energy Res.

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“…With the development of the advanced steam turbines, the length of the last stage blades has been up to 1500 mm [9] and the tip/ hub ratio is 2.5 [10]. The shock waves generated by the supersonic flow interact with the steam seal leakage flow near the endwall and the secondary flow [11], forming a more complex flow, as well as the non-equilibrium characteristics of wet steam [12], making it more difficult to evaluate the aerodynamic performance of the last stage blades. In addition, the damping structures such as nozzle dehumidification, rotor lacing wire, and shroud further increased the complexity of the last stage flow.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Aerodynamic Characteristics of Blades at the Last Stage of a Steam Turbine at Off-Design Conditions

Yun-feng

Jia

Zhou

et al. 2022

International Journal of Aerospace Engineering

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Experimental investigations have been carried out on the flow characteristics of the last stage long blades operating under off-design conditions. A model turbine test rig similar to a small power station was applied. The last stage blades with a scaling factor of 1 : 4.8 was used for pneumatic experiments. The rotor blade height was 375 mm, and the rotation speed was set to 7200 rpm. Five volumetric flow coefficients were utilized, corresponding to φ =0.61, 0.77, 0.92, 1.02, and 1.15. Pneumatic probes were used to focus on measuring pressures and swirl angles. The variation of different pneumatic parameters along the span and circumferential direction was investigated. The change patterns of the three-dimensional aerodynamic characteristics of the last stage blades during the off-design conditions were revealed. Results indicated that there was a high correlation between the variation of pneumatic parameters and different off-design conditions. In particular, the large meridional expansion angle at the tip led to abrupt changes in the inlet parameters, and the overlap even occupied by 17% blade height. Due to the influence of the exhaust hood, the circumferential static pressure-unevenness was up to 77.8% at the last stage outlet.

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“…Many researchers focused on heat transfer enhancement technology in regenerative cooling (Ulas and Boysan 2013;Brinda and Sumangala 2016;Feng et al, 2017;Pu et al, 2018;Zuo et al, 2018;Han et al, 2021;Liu et al, 2022;Luo et al, 2022). Han et al (2021) intended to improve the heat transfer performance of n-decane under supercritical pressure in horizontal tubes by adding ZnO nanofluids and summed up heat transfer corrections in detail.…”

Section: Introductionmentioning

confidence: 99%

Heat transfer and flow structures of supercritical n-decane in a regenerative cooling channel loaded with non-uniform heat flux

Liu

Ma³

et al. 2022

Front. Energy Res.

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A harsh and complex thermal environment in the combustor threatens safe working of scramjets. In this study, heat transfer and flow structures of supercritical n-decane under 3 MPa in a regenerative cooling channel loaded with non-uniform heat flux distributions are investigated, including uniform, sinusoidal, increased, and decreased heat flux distributions. A verified k–ω SST turbulence model was employed, and a corresponding mesh independence study was performed. From this work, the fluid temperature at the outlet of the heated channel is only determined by the averaged heat flux, and all the regenerative cooling channels achieve the same temperature although loaded with different heat flux distributions. Compared with the fluid temperature, the wall temperature distribution is more sensitive to the variations of heat flux distribution. The regenerative cooling channels loaded with the sinusoidal heat flux distributions exist in several high-temperature regions, and the channel loaded with linear distributions changes the trend of temperature distribution. A larger temperature gradient is found in the regenerative cooling channel wall with a lower thermal conductivity. This work provides a good insight into the characteristics of the flow and temperature field of regenerative cooling channels loaded with non-uniform heat flux considering the effect of conjugate heat transfer.

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Experimental and numerical investigation of the transition progress of strut-induced wakes in the supersonic flows

Cited by 19 publications

References 47 publications

Influence of grooved rib tip structure on tip loss and heat transfer in a gas turbine blade

Influence of grooved rib tip structure on tip loss and heat transfer in a gas turbine blade

Experimental Study on the Aerodynamic Characteristics of Blades at the Last Stage of a Steam Turbine at Off-Design Conditions

Heat transfer and flow structures of supercritical n-decane in a regenerative cooling channel loaded with non-uniform heat flux

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