Turbine Shaft Research Articles

PROSES PEMBUATAN POROS TURBIN PROPELER DENGAN BAHAN BAJA KARBON RENDAH ST.37 DI LEMBAGA ILMU PENGETAHUAN INDONESIA

The shaft is a rotating stationary member, usually spherical in cross section, the shaft may receive bending loads, tensile loads, compressive loads or torsional loads acting alone or in combination with one another. The propeller turbine shaft is made using a conventional lathe from the Indonesian Institute of Sciences (LIPI). The shafts made have stratified diameters with diameters of 8 mm, 10 mm, 15 mm and 24 mm with an overall length of 595 mm and has a thread in one part of the shaft. The axle uses ST.37 material, dural rod material and for the outside of the shaft (casing) using aluminum. Dural is a high strength aluminum based alloy with the addition of copper, magnesium and manganese.

Impact of Wind Power Penetration on Wind–Thermal-Bundled Transmission System

The wind–thermal-bundled transmission system is a feasible way to transmit wind power generation; however, the stability of the system should be paid more attention under high wind power penetration. In this article, the impact of wind energy penetration on torsional vibration and electrical characteristics is investigated for wind–thermal-bundled transmitted by high-voltage direct current system. The torsional vibration responses of generator shaft with different wind–thermal-bundled ratios are analyzed by time and frequency methods. The electrical characteristics of wind–thermal-bundled transmission system are disclosed under the influence of the wind farm penetration. The analysis illustrates that the penetration of doubly fed induction generation makes the torsional vibration of turbo generator and wind turbine shaft present different mode characteristics, and the risks of different modes are different. The current and voltage of wind–thermal-bundled transmission system show regular evolution with the change of wind–thermal-bundled proportion. Analytical results provide the value for the design and control of the wind–thermal-bundled transmitted system, which contributes to the improvement of power system stability.

Investigation on operational stability of main shaft of a prototype reversible pump turbine in generating mode based on ensemble empirical mode decomposition and permutation entropy

Investigation on operational stability of main shaft of a prototype reversible pump turbine in generating mode based on ensemble empirical mode decomposition and permutation entropy

Transient heat transfer performance prediction using a machine learning approach for sensible heat storage in parabolic trough solar thermal power generation cycles

Although solar thermal energy is one of the most promising renewable energy sources, intermittency often limits its potential. Thermal storage is the key technology for adjusting the time gap between the supply and demand of renewable energy. Even if the performance of sensible heat storage can be analyzed using numerical simulations or experiments in conventional technology, any method is time-consuming due to its time-dependent nature. In this work, a methodology to predict the transient heat transfer performance of sensible heat storage, which is used with direct steam generation parabolic trough solar thermal power generation cycles, based on a machine learning technique is developed. This methodology can handle varying fluid flow rates and is, therefore, advantageous for temperature control problems. To demonstrate the capabilities of the proposed method, regression models are trained using transient heat transfer analysis results based on the weather data of Bawean Island, Indonesia. During the regression model training process, Gaussian process regression shows the best prediction accuracy among 26 regression models. The prediction errors of 14-day consecutive operation turbine shaft work are 1.45 % or less, compared to the transient simulation results. The trained regression model is also applied to Kupang, about 1300 km apart from Bawean. The turbine shaft work prediction errors of 14-day consecutive operations are 3.24 % or less. Because of a significant computational time reduction, the proposed methodology is suited for solar thermal power generation site selection and plant concept design.

Effect of Change in Startup Cycle Time on Transient Thermal Stresses in Steam Turbine Rotor

During the turbine start stop period, occuring at brief intervals , the temperature of the steam turbine rotor varies. Because of the significant temperature gradients, this shift in temperature causes transitory thermal stresses in the rotor. Changes in material parameters such as thermal expansion coefficient ,modulus of elasticity, thermal conductivity, specific heat, Poisson's ratio, and others cause transient stresses. Thermal and mechanical stresses are applied to the turbine rotor. Before designing the rotor, it is necessary to estimate transient thermal stresses. The finite element study of a 210 MW steam turbine rotor for transient thermal loading is investigated in this paper. 30Cr1Mo1V was used to make the rotor. CAD software (PRO-E) was used to create the high-pressure turbine model. Since the steam turbine shaft (rotor) was symmetric about the axis along which it rotates, the model was solved using a 1 Degree slice model. Ansys 11 was used to investigate the FE model for transient thermal stresses for reduced cold start up cycle. The analysis was carried out for start up cycles of 560, 440 and 320 minutes respectively. The comparative results were studied and it was observed thatalthough the transient thermal stresses in the reduced cold start up cycle of 440 minutes are higher as compared to the transient thermo-mechanical stress value for actual cold start up cycle (560 minutes) but are within safe limits of yield and tensile strength. The thermal stress values for the other reduced cold start up cycle (320 minutes) re quite higher than the allowable yield and tensile strength of the material and hence cannot be considered as feasible start up cycle. Thermal stresses in the transient state were found to be significantly higher than steady state thermal stresses.

Model predictive control for gas turbine shaft speed based on model compensation using extended state observer

Gas turbine engines have offered advanced power generation with relatively small size on marine vessels. The operational flexibility has high control requirements for shaft speed regulation. Model predictive control provides a methodology for safe and efficient operation of gas turbines. However, when working at partial load, the controller degrades due to the mismatch between predictive model in model predictive control and dynamics of gas turbine. To deal with the issue of model adaptability in model predictive control, model compensation–based model predictive control is proposed for the gas turbine operation. The dynamics of the plant is modified by the extended state observer to get close to the pure integrator. The model predictive control is devised based on the modified plant. The wide-range load regulation and disturbance rejection of gas turbine have been improved by leveraging the benefits of model compensation–based model predictive control.

Design Methodology and Mission Assessment of Parallel Hybrid Electric Propulsion Systems

Abstract An integrated engine cycle design methodology and mission assessment for parallel hybrid electric propulsion architectures are presented in this paper. The aircraft case study considered is inspired by Fokker 100, boosted by an electric motor on the low-pressure shaft of the gas turbine. The fuel burn benefits arising from boosting the low-pressure shaft are discussed for two different baseline engine technologies. A three-point engine cycle design method is developed to redesign the engine cycle according to the degree of hybridization. The integrated cycle design and power management optimization method is employed to identify potential fuel burn benefits from hybridization for multiple mission ranges. The sensitivity of these mission results has also been analyzed for different assumptions on the electric powertrain. With 1 MW motor power and a battery pack of 2307 kg, a 3% fuel burn benefit can be obtained by retrofitting the gas turbine for 400 nm range. Optimizing the power management strategy improves this fuel burn benefit by 0.2-0.3%. Redesigning the gas turbine and optimizing the power management strategy, provides a 4.2% fuel benefit on 400 nm. The results suggest that a high hybridization by power, low hybridization by energy, and ranges below 700 nm are the only cases where the redesigned hybrid electric aircraft has benefits in fuel burn and energy consumption relative to the baseline aircraft. Finally, it is found that the percentage of fuel burn benefits from the hybrid electric configuration increases with the improvement in engine technology.

Comparison of Impact on Turbine Shafts Torsional Behavior for Integration of Two Types of Wind Farm into a Series-Compensated Transmission System

Deep decarbonization is the goal of modern power systems, so it is inevitable that large-scale wind farms will be integrated into systems. This also gives rise to many problems, which have been studied in detail in the literature. However, these studies basically have two deficiencies. One is to assume that traditional generator units are fully loaded, and the other is not to compare the differences in the impact of different types of wind farm. This paper discusses these two points in detail. Taking a series-compensated transmission system as the research object, and assuming that the wind farm only replaces part of the power of the traditional generator unit in the transition period of energy conversion, the difference between the torsional vibration behaviors of the traditional unit caused by adopting different types of wind farm is discussed. The results of the study show that the impact of integration of the type 3 wind farm is dominated by the induction generator effect of doubly fed induction generator units. The penetration rate as low as 19% could cause instability. However, the paralleled metal-oxide varistor can effectively improve the stability. For the type 4 wind farm, the dominant factor turns out to be the de-rating operations of the steam turbine generator unit. The allowable penetration rate depends on the turbine damping. When the turbine damping is sufficient, the penetration rate can be as high as 87.5%. In conclusion, in order to integrate wind farms into a series compensated transmission system, one should not only focus on the compensation factor to avoid the sub-synchronous torsional vibrations, but also pay attention to the types of wind farm as well as the penetration rate. The findings can be used as the decision-making basis for the integration of wind farms during the energy transition period.

An experimental study on the low-temperature spray characteristics of aviation Jet A-1 fuel with rotational speeds in a slinger-type atomizer

A slinger nozzle is a device that atomizes fuel using centrifugal force generated by rotation of the gas turbine shaft. This nozzle is easy to design and manufacture and has excellent atomization performance at high speed rotation, making it suitable for small gas turbine engines. In this experimental study, the spray characteristics of a slinger nozzle were investigated using a high-speed camera and a 2-dimensional phase Doppler anemometry (PDA) system, and the velocity components and the mean droplet size (SMD) of the spray were obtained at rotational speeds of 5000 to 30,000 rpm. Water and Jet A-1 were used as working fluids, and due to the difference in the physical properties of the fluids, column- and sheet-shaped sprays appeared, respectively. The sheet-shaped spray was found to be favorable for initial droplet generation. Accordingly, Jet A-1 disintegrated and formed initial droplets faster than water at the spray center of Y/do = −1 to +1. The droplet sizes of the water and Jet A-1 sprays crossed at a nozzle rotational speed of 17,000 rpm, and thereby, the dominant variables that affect droplet formation, such as viscosity and surface tension, could be identified based on this rotational speed. As the temperature of the Jet A-1 decreased, the sheet-shaped spray changed to ligament-shaped sprays at the nozzle orifice exit, and the droplet size increased due to the increased viscosity, which disturbed the ligament breakup. Finally, mathematical expressions were presented to predict the mean droplet size (SMD) of slinger nozzle sprays based on the previous results and experimental data. These apply to the determination of the ignition condition of the slinger-type gas turbine combustor.

Dynamic reliability analysis of main shaft bearings in wind turbines

Tapered roller bearings (TRBs) are widely employed in large wind turbines as main shaft supports. The reliability of TRBs is directly related to the operational efficiency and safety of wind turbines. In this paper, a method for dynamic reliability analysis of TRBs used for supporting the main shafts of wind turbines is presented. First, a new quasi-static TRB model is established based on the meta-heuristic optimization algorithm. Then, the influence of preload, bearing clearance, and friction on the fatigue life of the TRB is investigated in detail. Moreover, considering the impact of uncertain factors, a dynamic reliability analysis of TRBs under fatigue load is conducted based on the composite limit state and adaptive double-loop Kriging theories. The effect of preload on the dynamic reliability of TRBs is assessed to guide the main shaft bearing assembly of wind turbines. Finally, a practical application example is provided to demonstrate the effectiveness and benefits of the proposed method.

ANALYSIS OF EXISTING SUPERCHARGING SYSTEMS AND PERSPECTIVES OF APPLICATION OF ELECTRIC DRIVE IN SUPERCHARGING UNITS

The article analyzes modern solutions for increasing engine power by improving the air supply system. Single-stage and multi-stage pressurization schemes with gas, mechanical and combined connection in several variations are considered, their positive and negative sides for modern mechanical engineering are revealed.
 The simplest and most common is the turbocharging system, in which the turbine rotates only under the exhaust gases and this drives the compressor. Consideration should be given to the features of the working process of two-stroke diesel engines. At low speeds, there is not enough energy from the exhaust gases to drive the turbocharger. The second option is schemes in which the turbine and compressor shafts are connected to the engine shaft using a mechanical transmission. Another scheme is also possible in which the compressor and turbine can be separately connected to the crankshaft. Such solutions ensure synchronous operation of the compressor and reciprocating engine in all modes, improve the gas exchange process, improve performance in transient conditions and improve starting properties. One successful solution for two-stroke diesel engines is the development of a combined supercharging system with an intercooler, which are already considered multi-stage systems. They are generally divided into two schemes, in the first scheme the drive compressor is a high pressure degree, and the turbocharger is low pressure, the second scheme is vice versa. It is the first option that is more often used for two-stroke diesel engines, since the power consumption for driving the compressor is less, which causes a slightly higher engine efficiency. Injectivity is close to engines with conventional gas turbine supercharging.
 Over the past 7 years, the approach to improving the pressurization system has undergone some changes, Electric Boosting Systems for civilian vehicles have appeared. One of the first companies were Audi, Daimler, Land Rover, which began to equip their vehicles with electric supercharging. Currently, such large companies as BorgWarner and Garrett can be considered ambassadors of this technology. For example, AMG, together with Garrett, developed and introduced serial electric turbocharging. The problem of using an electric drive in boost systems has been lately gaining more publicity, it is already possible to conclude that there is great potential and the possibility of using such developments for domestic two-stroke diesel engines.

Influence of Number of Flat Locally-Fabricated Turbine Blades on the Performance of a Simplified Pico Hydropower System

Five locally fabricated turbines with 3, 5, 7, 9 and 11 flat blades were locally fabricated and tested in conjunction with a vertical penstock of diameter 0.0762 m and nozzles of diameters 0.0158, 0.0212, 0.0266, 0.0343 and 0.042 m in a simplified Pico hydropower system. This study is an aspect of an ongoing work aimed at ultimately implementing the system for small power generation. The turbines were mounted at the foot of an overhead reservoir 6.95 m high. A 1.11 kW pump was used to recycle the water downstream of the turbine from an underground reservoir to the overhead reservoir, and a 3.9 kVA alternator used for the on-load tests. The turbine was linked to a 3.9 kVA alternator by a belt drive of pulley ratio of 6:1. The mean rotational speeds of each turbine and alternator shafts, volume of water displaced, and voltage developed were measured for each nozzle diameter. These data were used to compute flow rate, shaft and electrical power, and efficiency for each operation. Dimensionless flow, head and power coefficients as well as specific speed were computed and functional characteristic curves relating plotted. The turbine with 11 blades developed the maximum voltage with the nozzle diameter of 0.042 m and the least voltage for 0.0158 m diameter nozzle. The corresponding estimated power output computed using the manufacturer’s specifications on the alternator was also highest and the mean maximum efficiency based on the estimated power output was 0.4482. This indicates that the larger nozzle diameters combined with the turbine with higher number of flat blades favour beneficial system operation. The results indicate good potential for the system as a simple, environmentally friendly and decentralized small power generation system that can contribute to the current energy mix in Nigeria.

Особенности проектирования высокотемпературных пластинчатых теплообменников для малоразмерных газотурбинных двигателей

An increase in the fuel efficiency of small-sized gas turbine engines can be achieved by regenerating the heat of the turbine exhaust gases. A rational layout solution in this case is a turboshaft scheme, where the effective power is generated on the shaft of a free turbine, and the turbine exhaust gases are released into the environment without doing useful work. When creating a turboshaft engine with heat recovery, the concept of developing engine family on the base of unified gas-generator was considered. The concept involves the development of a modular system, where the addition or exclusion of individual large units allows changing the type of engine at minimal cost. The article presents the layout solution of a small-sized turboshaft gas turbine engine with heat recovery, developed on the basis of a unified gas-generator and using a gearbox to transfer effective power to a propeller or a rotor. A plate heat exchanger module with a corrugated heat exchange surface for a small-sized turboshaft gas turbine engine has been designed. The heat exchange matrix was developed using a complex techniques of computer-aided design, calculation and manufacture of plate heat exchangers. Some design features of high-temperature plate heat exchangers are identified, the most important of which is the non-uniformity of temperature fields in the heat exchange matrix. Taking into account the non-uniformity of temperature fields, the heat exchanger module is a collapsible structure allowing the replacement of the heat exchange matrix and providing compensation for thermal expansion of the heat exchanger elements. The designed plate heat exchanger module for a small turboshaft gas turbine engine will be manufactured and tested on the bench

Study of Torsional Vibration Bifurcation Characteristics of Direct-Drive Wind Turbine Shaft System

This paper set out to establish the dynamics model of shaft torsional vibration for direct-drive wind turbine with the phenomenon of unstable shaft system torsional vibration. The stability of the equilibrium point of the dynamical model is investigated, and the Routh–Hurwitz stability criterion is used to obtain a range of values for the bifurcation control parameters. For the stable equilibrium point, the stability domain of the system is calculated by constructing the Lyapunov function. The sensitivity analysis of system parameters is carried out to obtain the law of the effect of system parameters on system stability of the torsional vibration system. The results are substituted for example calculations, and the results verify the correctness of the theoretical analysis conclusions. It is proved that it is feasible to analyze the torsional vibration characteristics of the direct-drive wind turbine shaft system by using the principle of Routh–Hurwitz stability, etc., which provides a reference for the structural design of direct-drive wind turbine.

Active Disturbance Rejection Control for Wind Turbine Fatigue Load

With the participation of wind power in grid frequency modulation, the fatigue load of the wind turbine increases accordingly. A new control method that considers both fatigue load and output power of wind turbine (WT) is proposed in this paper. A linear active disturbance rejection control (LADRC) is designed and applied for the pitch angle in the wind turbine load reduction control. The particle swarm optimization (PSO) algorithm is used to optimize the parameters of the wind turbine controller, and the total variation of the wind turbine shaft torque and tower bending moment is added to construct a new objective function to further reduce the fatigue load of the wind turbine. The design-optimized controller is validated on a 5 MW wind turbine in SimWindFarm. The simulation results show that the LADRC controller can accurately track the reference power of the wind turbine, reduce the pitch angle fluctuation of the wind turbine, reduce the fatigue load of the wind turbine, and improve the service life of the wind turbine.

A probabilistic combined high and low cycle fatigue life prediction framework for the turbine shaft with random geometric parameters

Combined high and low cycle fatigue (CCF) is a common failure mode of turbine shaft. This study presents a generic procedure for probabilistic CCF life prediction, and combined with the modified highly stressed volume (HSV) method to improve a prediction framework, which considers the effect of random geometric parameters on fatigue life and establishes the dynamic relationship between key geometric parameters and life distribution. The probabilistic CCF life modeling of turbine shafts with stochastic geometric parameters is presented, whose predicted result is consistent with practical engineering. This research is of great significance for life estimation and prolongation of turbine shaft.

Synthetic jets as a flow control device for performance enhancement of vertical axis hydrokinetic turbines: A 3D computational study

In the present work, a vertical axis turbine with straight blades was analyzed through a numerical simulation in three dimensions, the performance of the turbine was studied while synthetic jets were used as an active flow control method. To carry out the simulations, the Unsteady Reynolds Averaged Navier-Stokes (URANS) equations were solved on Star CCM+, through the k-ω SST turbulence model. The dynamics of the turbine movement were described using the Overset Mesh technique, capturing the transient characteristics of the flow field. Hydrodynamic coefficients and vorticity fields were obtained to describe the flow behaviour, and the results were compared with two-dimensional simulations of the same system. Turbine performance with tangential synthetic jets located on the intrados and extrados of the airfoil shows an increase in the torque and power output of the turbine. Moreover, using simple estimates, synthetic jets used less power than the increment in power generated at the turbine shaft, showing that efficiency of the turbine increases with the use of synthetic jets. However, the increment in the turbine performance is not as high as in previous two-dimensional studies reported in the literature.

FEM numerical simulation of contact stresses between driving shaft and hub impeller of fuel pump

The aim of the work was to test the contact stresses in the model system of the turbine hub cooperating with the fuel pump drive shaft. The hypothesis of the work was that, by means of FEA, it is possible to assess the contact stresses in the materials of the turbine hub and the fuel pump shaft during torque transmission. A turbine with fibre-reinforced polyphenylene sulphide (PPS) composite cooperating with a stainless steel shaft (X46Cr13/1.4034) in a commonly used D-flat shape joint was selected for the experimental research. To assess contact stresses, the CAD model (NX, Siemens) of the entire turbine was limited to the hub area. The drive shaft is supported in accordance with the bearing in the fuel pump, and the possibility of rotation about the axis along the length of the torque-producing magnet is taken away. The system was loaded with a torque of 200 Nmm on the turbine. The turbine hub and shaft were calculated, taking into account the phenomenon of contact detachment or slip at the value of the friction coefficient of 0.1. The pressure transmission area was found in the area at the edge of the flat surface D-flat and on the opposite side of the D-convexity. The contact stresses on the D-flat side reached values close to the composite strength. The studies did not take into account the technological inaccuracies, thermal deformation, local material properties, and wear. The value of the friction coefficient was not measured in realistic conditions with fuel lubrication. FEA has been achieved, which allows to reduce the cost of experimental research. The proposed model allows for further studies of the influence of elasticity of various materials and structures on contact stresses in order to assess wear resistance.

A Method for Constructing a Three-phase Aircraft Network Stabilized in Frequency and Voltage with an Asynchronous Generator on the Turbine Shaft

Frequency converters with various designs of the power circuit are widely used for supplying power to autonomous objects (e.g. aircraft, helicopters, etc.). Three-phase generators with variable frequency and voltage level, which are as a rule installed on the jet turbine shaft, behave as primary sources of electric power in this case. To obtain a stabilized three-phase output voltage, a two-level converter circuit has been widely used, which consists of an uncontrolled rectifier, a DC link, and a voltage-source inverter. Recent years have seen an interest in using direct frequency converters, in which the primary "poor" network is transformed into a stabilized secondary network within a single stage. To this end, modern topologies of the power circuit and algorithms for its control are used. The essential advantages of direct frequency converters are that they do not contain a DC link with bulky electrolytic capacitors of large capacitance, and their ability to perform energy conversion in one stage. Of particular interest is the possibility of using an asynchronous generator as the primary source of the onboard network. By combining it with a matrix direct frequency converter, in which the switch control algorithm developed by the authors is used, it becomes possible to obtain a high-quality on-board network for autonomous objects, which is stabilized in amplitude and frequency.

Study on turbocompound system for a heavy-duty diesel engine by combining matching analysis with experiments

In this work, to improve the fuel economy of long-haul commercial vehicles, the effects of turbocompound system matching on engine performance were numerically and experimentally studied. Firstly, a 1D GT-POWER simulation model of an 11 L heavy-duty diesel engine was established and verified by the experimental data. Secondly, the performances of the turbocompound engine matching with different sizes of fixed geometry turbine (FGT) and power turbines were analyzed. It was found that the exhaust energy distribution between the turbocharger turbine and power turbine had a significant impact on engine performance, and the size of the turbocharger turbine had a more noticeable impact than the power turbine. Based on the FGT turbocompound system simulation result, an appropriate variable geometry turbocharger (VGT) and three wastegate turbochargers (WGT) were selected for further simulation and experimental research. In addition, the impacts of the transmission ratio between the power turbine shaft and the engine crankshaft, and the fuel injection timing on the engine performance were experimentally studied. The engine test result showed that the fuel economy was improved by 1.6% under European Steady State (ESC) cycle while keeping the weighted NOx emission the same as the original engine. Finally, the turbocompound engine with WGT was installed on a heavy-duty long-haul commercial vehicle for road tests. The fuel economy of the vehicle was improved by 2.54% under the 80 km/h constant speed road test.