Aerothermodynamic Design and Flow Characteristics for a S-CO_(2) Radial Inflow Turbine

In this paper,a radial inflow turbine is designed for the 150 kW S-CO_(2) Brayton cycle system,and flow characteristics and off-design performances are analyzed.The design results are accurate and high performances can be achieved for the S-CO_(2) power system,and the total-static efficiency of 86%and net output power about 285.2 kW can meet the design requirements of S-CO_(2) cycle system.The results of the flow characteristics show the streamlines of radial inflow turbine distribute uniformly,and the vortexes generated at the shroud of the blade suction surface have little influence on the turbine performances.The off-design performances show the total-static efficiency remains above 80%in the pressure ratio range of 1.6~2.9,and the output power and mass flow rate increase with the pressure ratio increasing.It is indicated that the designed turbine has excellent off-design performances and can meet the operation requirements.The study results can provide guidance for S-CO_(2) radial inflow turbine design and operation.

Particle deposition patterns on high-pressure turbine vanes with aggressive inlet swirl

Characteristics of particle migration and deposition were numerically investigated in presence of aggressive swirl at the turbine inlet.The isolated effects of the inlet swirl were considered in detail by shifting the circumferential position of the swirl and by implementing positive and negative swirling directions.Particles were released from the turbine inlet and the resulting deposition on the vanes was determined by using the critical velocity model in a range of particle diameters from 1 to 25 lm.Results show that the particles are more likely to move outwards to the boundary walls of the passage by the action of the swirling flow.However,this could be relieved by increasing the particle size.An imbalance problem of the deposition is found between the adjacent vanes,which could introduce additional inlet non-uniformities towards the downstream rotor and thus accelerate performance degradation of the turbine stage.Overall,the negative swirl case has higher overall capture efficiency within the entire turbine than the positive swirl case for larger particles,and when the inlet swirl is shifted to the mid-passage of the turbine,more deposits could be produced in comparison with the case in which the swirl aims at the vane leading edge.

A k-ε Turbulence Model Considering Compressibility in Three-Dimensional Transonic Turbulent Flow Calculation

Based on the standard k-ε turbulence model, a new compressible k-ε model considering the pressure expansion influence due to the compressibility of fluid is developed and applied to the simulation of 3D transonic turbulent flows in a nozzle and a cascade. The Reynolds avenged N-S equations in generalized curvilinear coordinates are solved with implementation of the new model. The high resolution TVD scheme is used to discretize the convective terms. The numerical results show that the compressible k-ε model behaves well in the simulation of transonic internal turbulent flows.

Using Whole Annealing Genetic Algorithms for the Turbine Cascade Inverse Design Problem

INTRODUCTIONInthelastfewyearstherehajsbeenagrowinginterestinthenumericalsolutionofconstrainedoptimizationproblemsofturbinegovernedbytheEulerorNavier-Stokesequations.Developmelltofturbinecascadeswithoptimumaerodynamicefficiencyhaslongbeenadesignchalle...

Numerical Study of Laminar-turbulent Transition on a Platein a Low-Speed Tunnel with Contoured Wall

Laminar-turbulent transition flow phenomena on a flat plate in a low-speed wind tunnel at different Reynolds numberswere studied numerically. The now calculation is based on an inviscid/boundary layer interaction method with modifiedAbu-Ghannam/Shaw (AGS ) transihon criterion. The test sechon has non- symmetric al contoured walls, and the plate islocated biased the bottom side with a height ratio of 26: 14. In test case of steady flow, a laminar-turbulent transihontakes place and a small separation bubble occurs on the upper side of the plate, when the inlet Reynolds number is assmall as 0.63lx10-6. The predicted transihon location agrees well with that of the test results, but the separation bubbleis hardly to see from the calculatod velocity profiles though the printed data of velocity in this region do show thenegahve values. The further numerical Predictions with different Reynolds numbers corresponding to the incoming flowvelocities show that when the Reynolds number is greater than 1.379xl0-6, the separahon bubble does not occur, whichis coincident with the experimental results. The influence of the side wall geomeny on the transihon on the plate is alsostudied.