Rotor Pressure Ratio Research Articles

Ceramic and Metal Additive Manufacturing of Monolithic Rotors From SiAlON and Inconel and Comparison of Aerodynamic Performance for 300W Scale Microturbines

Abstract The gas turbine industry is continuously developing and testing new materials and manufacturing methods to improve the performance and durability of hot section components, which are subjected to extreme conditions. SiAlON and Inconel 718 are especially desirable for turbomachinery applications due to their high strength and high-temperature capabilities. To demonstrate the viability of additive manufacturing for small-scale turbomachinery for 300W scale microturbines, a monolithic rotor with a design speed of 450,000 RPM containing radial turbine and compressor was developed considering additive manufacturing constraints. The geometry was manufactured from SiAlON and Inconel 718 using lithographic ceramic manufacturing and selective laser melting, respectively. The additive manufacturing and thermal process parameters as well as material characterization are described in detail. Surface and computerized tomography scans were conducted for both rotors. While the metallic rotor showed undesirable printing artifacts and a large number of defects, the ceramic part achieved a level of relative precision and surface quality similar to large-scale production via casting. To compare turbomachinery performance, an aerodynamic test facility was developed allowing to measure pressure ratios and efficiency of small compressors. The rotors were tested in engine-realistic speeds, achieving a compressor rotor pressure ratio of 2.2. The ceramic part showed superior efficiency and pressure ratio compared to the Inconel rotor. This can be explained by lower profile and incidence losses due to a higher fidelity physical representation of the model geometry and better surface finish.

Experimental and Computational Investigation of an Advanced Casing Treatment in a Single-Stage High-Speed Compressor

Abstract An advanced casing treatment (CT) design was tested in a single-stage, high-speed axial compressor. The geometry of the casing included bent-axial slots applied near the rotor leading edge. Compressor performance and stall margin (SM) measurements were acquired for both casing treatment and for the smooth wall case at four different corrected speeds. The measurements also included rotor-exit radial traverses of unsteady total pressure. The results indicated an increase in rotor pressure ratio at all operating conditions with the application of the casing treatment. The stall margin also increased at all rotor speeds. Efficiency increases were observed with the casing treatment at design conditions and some off-design conditions. Numerical simulations of the IGV, rotor, and stator were conducted with and without the casing treatment. These results served to validate the efficacy of the part-wheel unsteady Reynolds-averaged Navier–Stokes (URANS) simulations to predict the effects of the casing treatment. The simulations also allowed a detailed study of the flow physics related to the interactions between the rotor and casing.

Numerical and performance analysis of one row transonic rotor with sweep and lean angle

In this study, aerodynamic behaviors of swept and leaned blades were investigated. Axial and tangential blade curvatures impacts on compressor’s operating parameters were analyzed separately. A commercial CFD program which solves the Reynolds-averaged Navier-Stokes equations was used to find out the mentioned impact and the complicated flow field of transonic compressor-rotors. The CFD method that was used for solving flow field’s equation was validated by experimental data of NASA Rotor 67. The results showed that the compressor with curved rotors had higher efficiency, rotor pressure ratio and stable operating range compared to the compressor with un-curved rotors. Using curved rotors mostly had higher impact on the overall stable operating range compared to the other operating parameters. Operating range involves choking point and stall point that were changed separately by using of bended blade. For finding the detailed impact of sweep and lean angle on transonic blades, various forms of lean and sweep angles were exerted to basic rotor. It was found that sweep angles increased overall operating range up to 30%, efficiency up to 2% and pressure ratio up to 1%. Leaning the blades increased the safe operating range, the pressure ratio and efficiency by 14%, 4% and 2% respectively.

Implementation of 3-Port Condensing Wave Rotors in R718 Cycles

The use of a novel 3-port condensing wave rotor is suggested to enhance the turbocompression in a refrigeration cycle that works only with water (R718) as a refrigerant. Although the implementation of such a wave rotor essentially reduces the size and cost of R718 units, their efficiency may also be increased. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor, all in one dynamic process. The underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. The thermodynamic process is shown in pressure-enthalpy and temperature-entropy diagrams. Based on the described thermodynamic model, a computer program was generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A performance map summarizes the findings. It shows optimum wave rotor pressure ratio and maximum relative performance improvement of R718 cycles by using the 3-port condensing wave rotor.

Preliminary Study of a Novel R718 Compression Refrigeration Cycle Using a Three-Port Condensing Wave Rotor

Using a novel 3-port condensing wave rotor enhancing the turbocompression in a R718 refrigeration cycle, which uses only water as a refrigerant, has been introduced. The wave-rotor implementation can increase efficiency and reduce size and cost of R718 units. The condensing wave rotor employs pressurized water to pressurize, desuperheat, and condense the refrigerant vapor—all in one dynamic process. The underlying phenomena of flash evaporation, shock wave compression, desuperheating, and condensation inside the wave rotor channels are described in a wave and phase-change diagram. The thermodynamic process is shown in pressure–enthalpy and temperature–entropy diagrams. A computer program based on a thermodynamic model was generated to evaluate the performance of R718 baseline and wave-rotor-enhanced cycles. The effect of some key parameters on the performance enhancement is demonstrated as an aid for optimization. A performance map summarizes the findings. It shows optimum wave rotor pressure ratio and maximum relative performance improvement of R718 cycles by using the 3-port condensing wave rotor.

Experimental performance evaluation of a 99.0 mm radial inflow nozzled turbine at larger stator-rotor throat area ratios

Following on from experimental data already presented by Spence and Artt in 1997, further comprehensive performance tests were carried out on a 99.0 mm radial turbine with three larger vaned stators. The results have helped to confirm some of the trends noted in the earlier tests. Measurements of the efficiency, mass flowrate and rotor pressure ratio are presented together with the results of a simple loss analysis. For smaller stator sizes the turbine mass flowrate is shown to be proportional to the stator throat area. The significance of the stator-rotor throat area ratio is examined and its dependence on the stage pressure ratio is noted.