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Centrifugal turbine which has less land occupation, simple structure, and high aerodynamic efficiency is suitable to be used as small to medium size steam turbines or waste heat recovery plant. In this paper, one-dimensional design of a multistage centrifugal steam turbine was performed by using in-house one-dimensional aerodynamic design program....
Citations
... One of the pareto-optimal members increased the impeller peak efficiency by 1.9 percent nevertheless the operating range could not be expanded. Another aerodynamic optimization approach with one dimensional calculations is given by Li in [10]. It was figured out that the one dimensional approach is basically the same than a 3D CFD calculation, which shows that the used program is reliable and effective. ...
The decarbonization of production processes plays an important role on the way to environmentally friendly economy. Especially, the implementation of high temperature heat pumps (HTHP) offers a great potential to replace fossil fuel-based energy infrastructure. A major issue for the introduction of HTHP is the initial cost and regarding the payback period. However, there is still potential in increasing the coeffcient of performance (COP) of HTHP for the economic integration in existing industrial processes. One important possibility is the dedicated development and design of turbocompressors for this application and the planned heat transfer medium including the aerodynamic optimization of compressor geometry. Against this background an automated aerodynamic optimization method for radial compressor blade geometry for superheated steam is presented. The optimization refers to two different operating points of the HTHP and focuses on maximizing the isentropic efficiency of the impeller geometry as well as the pressure ratio. The algorithm is accelerated by data-driven metamodels and is implemented in a high-performance cluster environment. The boundary condition of the inherent computational fluid dynamics (CFD) calculation comes from the thermodynamic cycle calculation of the whole HTHP system. A two-stage compression with intercooling between the compressor stages are foreseen. Our approach shows an increment of both objective functions in both operating points and the satisfaction of further side conditions for the low pressure compressor (LPC). Furthermore, it results in an increment of 5 percent points of isentropic efficiency and 13 percent points of static to total pressure ratio in comparison to our initial geometry. These impeller optimizations result in a COP increment of 5 percent. The resulting geometry will be interpreted in the context of aerodynamic behavior. Based on that results additionally, a flow-cut optimization for the high pressure compressor (HPC) is given and evaluated. The results are comparable to aerodynamic optimization in different research fields like aircraft engines or stationary gas turbines and contribute to optimized multistage compressor design for HTHP.
... Mechanism innovation is the core of mechanical system innovation. The research of mechanism synthesis is the primary problem in modern mechanical design [1][2][3][4]. Multilinkage robot is a mechanism consisting of several moving pairs linked together by rigid rods. It is widely used in chemical, textile, metallurgy, petroleum, medical, and other fields with high flexibility, good obstacle avoidance performance, better singularity avoidance of mechanism, and easy to manufacture. ...
Type synthesis of mechanical structure is of great significance to the realization of mechanism target function, systematization, and stability of mechanical device. The type synthesis method of multilinkage robot has been given high demands with increasing number of degrees of freedom and high flexibility in special occasions. In order to improve the workspace and flexibility of mechanism, this paper studies the existing type synthesis theory and proposes a type synthesis method of modular combination with virtual rotation centers. Firstly, modular units are built. Secondly, modular units are expanded according to the needed paths. In the end, the expanded modular units are combined to form the kinematic linkages. Based on the proposed method, the configuration design of the aerial working platform and the self-adaptive levelling platform is completed. The stabilities of two platforms are checked by modal analysis. The prototype products are manufactured, respectively, for further verifying validity of the method. The designed aerial working platform with virtual rotation centers can achieve 360° rotating large workspace, more compact mechanical structure, and short arrival time at the same height than the common scissor-type and mast-type aerial working platforms. The designed adaptive levelling platform is tested that ensures the levelling of the upper surface at different inclinations. The method can provide new idea for the mechanism configuration and expand the application scope of new mechanisms.
... Therefore, the layer mesh quality requirement of the SST model is higher than that of the k-epsilon model. Reference [18] demonstrated that when the computational grid number is very large, the k-epsilon model is used as the turbulence model in simulating turbomachinery in order to relax the demand on computer memory and raise the efficiency. The calculated residuals converge below 10 -5 . ...
In some situations, the improvement of the thrust-to-weight ratio (TWR) of microturbine engines (MTEs) for energy-, economic-, and environment-related reasons can be achieved for military or civilian purposes. However, due to limitations of existing traditional MTE technology, it is difficult to meet the key requirements of small aircraft for high energy/power density and low-cost power, especially for long-endurance drone swarms. To address these problems, a novel compact concept of a high-TWR of MTE with a double-sided composite impeller (DSCI) is proposed in this research. First, the principle and structure of the concept are explained through theoretical analysis, and its potential advantages are discussed. Second, the DSCI is analyzed at the top level, and the design principle and important parameters are discussed. The DSCI and supporting jet engine are preliminarily designed. Then, their weight is estimated. Finally, theoretical analytical and numerical simulations are used to preliminarily research the performance parameters of DSCI jet engine at the design point, and the parameters are discussed. These calculations showed encouraging results, with all components of the DSCI jet engine meeting matching characteristics. Compared to the JetCat P500-PRO-GH, the DSCI jet engine has a 39.4% increase in TWR and a 36.82% decrease in specific fuel consumption (sfc). This study lays a foundation for the development of high energy/power density MTEs in the future.
... To resolve the above difficulties, the radial-outflow expanders can be a good alternative [8][9][10][11][12][13][14][15][16][17][18][19]. As the name suggests, the working medium flows outwards along radial direction in radial-outflow expanders, such a featured structure makes it capable for resolving the aforementioned inherent problems of the radial-inflow expanders. ...
Radial-outflow turbo-expanders have emerged in the recent years to suit some special applications where complex multi-phase and multi-component flows (like liquid-rich gases and solid particle-laden gases) need to be expanded. This paper presents a systematic study on the design and flow behavior of a single stage radial-outflow turbo-expander, which is to be used in organic Rankine power system to covert the low-temperature heat into shaft power. A mean-line code coupled with the optimization algorithm is developed and used to carry out the one-dimensional preliminary design, where 7 non-dimensional parameters are used as design variables (nozzle velocity coefficient, rotor velocity coefficient, reaction, rotor inlet and outlet flow angles, velocity ratio, and rotor diameter ratio). In comparison with the original design, significant design performance gains are achieved with the matched combination of design parameters. Geometric shape design is further performed for the expander. In consideration of the flow features in nozzle and rotor blade passages being nearly two-dimensional, blade shape design of both rows is conducted on the basis of the airfoils used for conventional axial flow turbines, where a conformal mapping method is used to convert the axial profile into the polar coordinate frame and it is then represented by 11 parameters of mean cylindrical diameter, radial and tangential chord, leading and trailing edge radius, blade inlet and outlet angles, blade inlet wedge angle, number of blades, unguided turning, and throat size. Flow and overall performance are simulated and predicted for the designed expander, where the output shaft power and overall isentropic efficiency is respectively predicted as 87.86 kW and 81.60% at design condition.
... the optimum pressure ratio of turbine is 0.24[16] ...
This paper investigates spontaneous condensation of wet steam in a centrifugal turbine by means of three-dimensional computational fluid dynamics. The flow field and aerodynamic characteristics of the wet steam in the centrifugal turbine are compared and analyzed by using the equilibrium steam and nonequilibrium steam models, respectively, where the latter applies the classical droplet nucleation theory and neglects velocity slip between the liquid phase and the gaseous phase. The state parameters of wet steam are described here based on the IAPWS’97 formulation. It is concluded that under the design condition, the mass flow rate, wetness fraction, and flow angle of the wet steam centrifugal turbine in the nonequilibrium steam model all change compared with the equilibrium steam model, with values of 4.4%, 0.5%, and 10.57%, respectively. Then the performance variation of the wet steam centrifugal turbine is analyzed under different steam conditions and different outlet back-pressure conditions. The results show that the change law of the mass flow rate, shaft power, and wetness fraction in the centrifugal turbine are basically identical in both models, and the mass flow rate, shaft power, wheel efficiency, and entropy loss coefficient of the centrifugal turbine in the nonequilibrium steam model are all higher than those in the equilibrium steam model, whereas the outlet wetness fraction is lower than that in the equilibrium steam model.
