Turbine Wheel Research Articles

"A Generator": A Mini Hydroelectric Apparatus as Renewable Source of Energy

Abstract--The matter is considered in the scope of sustainability and initially the basis and content of the term is defined. Based on this definition, the qualities of water and water energy are inspected as water is one of the most important type of clean energy source. Water energy is a time-honored renewable energy whose use dates back to earliest periods in history. The subject titled “A Generator” is a small but significant support to environmental protection as it defines a patented object which generates energy from water with a mini apparatus. 
 Protection of future lives of creatures and keeping them in infinite existence necessitate taking measures in advance. Concepts such as environment protection, sustainability, green energy, green economy etc. have also been under consideration by the UN since the 1970s. The subject is very comprehensive. This paper inspects as required hydroelectric power plants which produce clean energy and date back to ancient times. Water, as main source of hydroelectric power plants, is collected in proper basins and thus provided with potential energy. Water is then dropped from heights to trigger its kinetic energy and canalized to turbine wheels, moving which it turns kinetic/mechanical energy into electric power. This basic characteristic of water is evaluated in a mini apparatus this time. And an apparatus of unaccustomed size is obtained, which could support electricity production in household wet areas.

Influence of the Radial Clearance on Outlet Velocity Losses in the Unshrouded Turbine Cascade

Small-size turbines of the aviation gas-turbine plants differ by their high output losses and a high sensitivity to the value of radial clearance over the rotor blades. An increase in this clearance, for example, in-operation results in the reduced power efficiency factor due to a change in the losses in the nozzle, in the turbine wheel and output losses. Test data of the cascade of an average reliability with the rotor blade height of 20.73 mm were given for the three clearances, in particular 0.22; 0.6 and 1.0 m. An increase in the losses in the upper zone was recorded for rotor and nozzle blades with an increase in clearance. It was shown that due to a change in the distribution behavior along the radius of absolute velocity С 2 output losses can either be increased or decreased or remain unchanged at a change in the clearance depending on the averaged angle of flow output from the cascade in the absolute motion α 2. To improve the methods of one-dimensional computation of the cascade using the integral characteristics of its lattices the method of definition of output losses was suggested taking into consideration radial nonuniformity of the velocity С 2 at a high clearance value. It is assumed that the flow velocity С 2 is constant along the radius at a minimum clearance value of 0.22 mm. A degree of the radial nonuniformity of velocity С 2 was taken into consideration using the cascade test data in different modes and at different clearances. The obtained test data on the influence of clearance on absolute losses with the output velocity are naturally not multi-purpose, because even for the cascade investigation, the kinetic energy of flow behind it depends not only on the clearance value and the averaged output angle but also on some other auxiliary factors.

Investigation of using multi-shockwave system instead of single normal shock for improving radial inflow turbine reliability

A variable nozzle turbine (VNT) has become an important technology for diesel engine applications. During the development and design process, one of the most important tasks is to minimize the risk of high cycle fatigue (HCF) failure. When a VNT operates with high inlet pressure and small nozzle opening, a shock wave may appear near nozzle vane trailing edge. The shock wave introduces strong excitation force on the downstream turbine blades and has a potential to damage the turbine wheel. To improve turbine reliability, a method of generating multi-shockwave system by using grooved surface nozzle was investigated. It was found that, in the multi-shockwave system, the intensity of the shock wave is weakened in comparison to original single normal shock wave, and its impact on the turbine wheel is therefore lowered. However, with the use of the grooved surface, penalty on the turbine efficiency is numerically found, but very small at the research point.

Fabrication processing and mechanical properties of Si3N4 ceramic turbocharger wheel

A composite technique was chosen to fabricate Si3N4 ceramic turbine wheel based on modified investment casting (MIC), slip casting (SP) and mold constraint hot isostatic pressing (MCHIP) aided by a near-net dimension using the gypsum mold and multi-piece Y2O3 ceramic mold. The detailed fabrication processing of Si3N4 ceramic turbine wheel was described. And the flexural strength and fracture toughness after different work temperature and speed were discussed. The results showed that owing to occurrence of phase transformation and chemical reaction, excess temperature resulted in interface cracking and interface debonding, flexural strength and fracture toughness decrease. Thermal expansion and centrifugal force under excessive high speed brought many pores in the microstructure and resulted in crack initiation and crack propagation. The critical work temperature was 700 °C and critical work speed was 100,000 r/min, which were obtained from the test and simulation results.

Numerical analysis for impacts of nozzle end-clearances on aerodynamic performance and forced response in a VNT turbine

It has been well known that nozzle end-clearances in a Variable Nozzle Turbine (VNT) are unfavorable for aerodynamic performance, especially at small openings, and efforts to further decrease size of the clearances are very hard due to thermal expansion. In this paper, both the different sizes of nozzle end-clearances and the various ratios of their distribution at the hub and shroud sides were modelled and investigated by performing 3D Computational Fluid Dynamics (CFD) and Finite Element Analysis (FEA) simulations with a code of transferring the aerodynamic pressure from the CFD results to the FEA calculations. It was found that increasing the size of the nozzle end-clearances divided equally at the hub and shroud sides deteriorates turbine efficiency and turbine wheel reliability, yet increases turbine flow capacity. And, when the total nozzle end-clearances remain the same, varying nozzle end-clearances’ distribution at the hub and shroud sides not only shifts operation point of a VNT turbine, but also affects the turbine wheel vibration stress. Compared with nozzle hub clearance, the shroud clearance is more sensitive to both aerodynamic performance and reliability of a VNT turbine. Consequently, a possibility is put forward to improve VNT turbine efficiency meanwhile decrease vibration stress by optimizing nozzle end-clearances’ distribution.

Interrelated Dimensional Chains in Predicting Accuracy of Turbine Wheel Assembly Parameters

The working capacity of any device primarily depends on the assembly accuracy which, in its turn, is determined by the quality of each part manufactured, i.e., the degree of conformity between final geometrical parameters and the set ones. However, the assembly accuracy depends not only on a qualitative manufacturing process but also on the assembly process correctness. In this connection, there were preliminary calculations of assembly stages in terms of conformity to real geometrical parameters with their permissible values. This task is performed by means of the calculation of dimensional chains. The calculation of interrelated dimensional chains in the aircraft industry requires particular attention. The article considers the issues of dimensional chain calculation modelling by the example of the turbine wheel assembly process. The authors described the solution algorithm in terms of mathematical statistics implemented in Matlab. The paper demonstrated the results of a dimensional chain calculation for a turbine wheel in relation to the draw of turbine blades to the shroud ring diameter. Besides, the article provides the information on the influence of a geometrical parameter tolerance for the dimensional chain link elements on a closing one.

The effects of microstructure and microtexture generated during solidification on deformation micromechanism in IN713C nickel-based superalloy

Nickel-based superalloy IN713C produced through investment casting route is widely used for turbocharger turbine wheels in the automotive industry. The produced microstructure and microtexture are not homogeneous across the turbine component due to geometrical factors and localised cooling rate during the casting process, which give rise to inhomogeneous deformation during service. In the present paper, two kinds of in-house fatigue tests, Low Cycle Fatigue (LCF) and High Cycle Fatigue (HCF), were conducted at 600 °C in attempt to simulate the actual fatigue conditions experienced by turbine wheels in turbocharger. From Geometrically Necessary Dislocation (GND) distributions and strain analyses, it is concluded that microstructure heterogeneity such as carbide precipitates distribution within dendritic structure network determine the failure micromechanics during LCF tests. In the early stage of LCF loading, crack principally initiated within near surface carbides that have been oxidised during high temperature exposure. The higher GND density at the tip of carbide precipitates due to oxidation volume expansion are found to facilitate easy cracks initiation and propagation. Moreover, the cluster-like carbides network and its distribution can accelerate oxidation process and crack growth effectively. Furthermore, in the later stage of crack propagation during LCF, the weak interdendrite areas rotate to accommodate increased strain leading to faster cracks propagation and hence final catastrophic failure. Serial section technique for 3-D visualisation was employed to investigate the crystallographic grain orientation correlation with fracture mechanics during HCF loading. It appears that the microtexure and grain orientations are more critical than the alloy microstructure in an area with a relatively uniform carbides distribution and weak dendrite structure where HCF failure occurred. Based on the slip trace analysis, it was found that most faceting occurred in Goss grains (<110>//LD) and on slip system with the highest Schmid factor. It is concluded that cracks were initiated on planes with high Schmid factors and assisted by the presence of porosity.

Investigation and New Approach to Determine Initial Depth of Circumferential Groove to Simulate Turbine Wheel Burst

Investigation and New Approach to Determine Initial Depth of Circumferential Groove to Simulate Turbine Wheel Burst

Design and Construction of a Mini Hydro Turbine Model

This research is aimed at design and construction of a mini hydro turbine generator that can be made available at the consumer level, so as to improve the generation and availability of power at lower rate without pollution to the environment so as to help boost power generation, quality of power to its power consumers in developing countries. Pelton’s wheel design was used for the turbine research. Water stored in a tank or reservoir at a three meter height contains potential energy, this water is allowed to fall on the turbine wheel which drives the turbine. The potential and kinetic energy available in the water is converted to mechanical energy by rotating the runner connected to the turbine blade. The runner is connected to the rotor part of the alternator (containing the permanent magnet) and the stator (containing the windings) which is kept at permissible air gap to the rotor for effective induction. The voltage is tapped out from the stator as a single phase output, which is used to power household utilities and other machineries which need power supply. The result obtained was gotten from the various tests carried out on this research the tests includes water flow rate test, stator coil resistance test, output voltage test, power quality test and rotational speed test. The output power result shows that domestic power could be generated at individual residential level this will help improve and stabilize the power in the national grid.

Modelling and analysis of a high-speed turbine impeller concerning mistuning

As-manufactured impellers behave significantly different from nominal impellers. There are no identical blades due to geometric and material deviations. In this paper three model updating procedures are discussed with the objective to achieve realistic models of as-manufactured impellers. The techniques are applied to radial inflow turbine wheel of an exhaust gas turbocharger. The first approach creates a model through optical measurement and mesh morphing. The second approach is based on a contactless measurement of blade individual vibration responses. An iterative update process gains the corresponding mistuning pattern and thus the associated model. Third, a model is found by an optimisation, that identified a mistuning pattern, that fits modal characteristics, which are evaluated during experimental modal analysis at vacuum. In-depth analyses of these models are realised to determine advantages and drawbacks of the procedures.

The Sonic Surface in the Inter-Blade Channel of the Last Stage Rotor Wheel in the Steam Turbine of Large Output

The paper deals with sonic surface in a modern turbine wheel consisting of non-prismatic ultra long blades. The whole inter-blade channel is choked. Different positions and shapes of the sonic line in particular cross-sections along the span are observed. The sensitivity of sonic line formation to small changes of effective shape of the inter-blade channel in the root section and the influence of inlet angle, stagger angle and pitch/chord ratio in the tip section are discussed. The problematic of sonic line development in the case of supersonic inlet flow filed is also described. The presented work is based on results of theoretical, experimental and numerical approaches.

Technological and Economical Assessment of Alternative Process Chains for Turbocharger Impeller Manufacture

Turbochargers boost the performance of combustion engines enormously: the motors are significantly smaller at the same power, consume less fuel and their exhaust emissions are lower. A further increase in performance requires turbine wheels that can withstand even higher specific loads. Gamma titanium aluminide is the ideal material for this. However, to date there is no process chain which permits an economical manufacturing of the component. Responsible for this are the difficult-to-access, filigree flow geometries and the material properties. Thus, there is a high need for a comprehensive evaluation of alternatives for impeller manufacture. In this paper, different manufacturing chains consisting of pre-finishing and finishing of near-net-shape parts are compared to each other for a given example geometry. Electrochemical as well as Electrical Discharge Machining technologies are taken into account as alternatives for conventional milling and grinding processes for the finishing of cast blanks or samples produced by additive manufacturing. Based on a technological analysis a cost comparison is executed, which allows an economical assessment of the different process chains regarding given boundary conditions and varying production quantities.

Modeling of turbine wheel assemblies taking into account the deformation of parts

The article researches an impeller. The assembly process requires to accurately adhere to the given assembly parameters. To do this, preliminary calculations are carried out, they must take into account a number of factors, such as tolerances in processing the parts to be assembled, the tensile-compression stiffness, torsional rigidity, and others. The article studies the influence of blades deformation with the contact pressure on the accuracy of the goods assembly parameters.

Instantaneous flywheel torque of IC engine grey-box identification

In this paper a mathematical model developed for the identification of excitation torque acting on the IC engine flywheel is presented. The excitation torque gained through internal combustion of the fuel in the IC engine is transmitted from the flywheel to the transmission. The torque is not constant but variable and is a function of the crank angle. The verification of the mathematical model was done on a 4-cylinder 4-stroke diesel engine for which the in-cylinder pressure was measured in one cylinder and the instantaneous angular speed of the crankshaft at its free end. The research was conducted on a hydraulic engine brake. Inertial forces of all rotational parts, from flywheel to the turbine wheel of the engine brake, are acting on the flywheel due to the nonuniform motion of the flywheel. It is known from the theory of turbomachinery that the torque on the hydraulic brake is a quadratic function of angular speed. Due to that and the variable angular speed of the turbine wheel of the engine brake, the torque during one engine cycle is also variable. The motivation for this research was the idea (intention) to determine the instantaneous torque acting on the flywheel as a function of the crank angle with a mathematical model without any measuring and based on this to determine the quality of work of specific cylinders of the multi-cylinder engine. The crankshaft was considered elastic and also its torsional vibrations were taken into account.

Fretting Fatigue Cracking of an Arresting Feature in a Turbine Disk of a Heavy-Duty Gas Turbine Engine

Abstract A check for surface cracks under application of the magnetic flux leakage method (MT testing) was performed on the turbine wheel disk of a heavy-duty turbine gas turbine engine for energy generation. It revealed unacceptable findings on the bearing surface of the sealing plate groove. In order to identify the damage-causing mechanism of the material, a metallographic examination was performed. The findings during non-destructive material testing were caused by a gaping material separation which was also easily detectable to the naked eye. The material separation is a high-cycle fatigue crack induced by fretting. Hence, the damage causing mechanism was fretting fatigue cracking.

Aerodynamic Optimization of the High Pressure Turbine and Interstage Duct in a Two-Stage Air System for a Heavy-Duty Diesel Engine

Turbochargers reduce fuel consumption and CO2 emissions from heavy-duty internal combustion engines by enabling downsizing and downspeeding through greater power density. This requires greater pressure ratios and thus air systems with multiple stages and interconnecting ducting, all subject to tight packaging constraints. This paper considers the aerodynamic optimization of the exhaust side of a two-stage air system for a Caterpillar 4.4 l heavy-duty diesel engine, focusing on the high pressure turbine (HPT) wheel and interstage duct (ISD). Using current production designs as a baseline, a genetic algorithm (GA)-based aerodynamic optimization process was carried out separately for the wheel and duct components to evaluate seven key operating points. While efficiency was a clear choice of cost function for turbine wheel optimization, different objectives were explored for ISD optimization to assess their impact. Optimized designs are influenced by the engine operating point, so each design was evaluated at every other engine operating point, to determine which should be carried forward. Prototypes of the best compromise high pressure turbine wheel and ISD designs were manufactured and tested against the baseline to validate computational fluid dynamics (CFD) predictions. The best performing high pressure turbine design was predicted to show an efficiency improvement of 2.15% points, for on-design operation. Meanwhile, the optimized ISD contributed a 0.2% and 0.5% point efficiency increase for the HPT and low pressure turbine (LPT), respectively.

ХАРАКТЕРИСТИКИ ПАРЦИАЛЬНЫХ МИКРОТУРБИН С МАЛЫМ УГЛОМ ВЫХОДА СОПЕЛ

The article presents the results of the pilot study of gas microturbine constructions both axial and centripetal, with a relatively big pitch of impeller blade and nozzles with small outlet angles. The case is that lowering the angle of a nozzle doesn’t solve the problem of low gas consumption when it is necessary to supply gas to the turbine wheel and to distribute it around blades. This makes execute microturbine steps with partial gas supply to the wheel. There were revealed instances when negative degree of reactivity was permitted. There has been found a degree of the impact to heat drop to the step with a change of partition, which makes the choice of operation mode of the microturbine well grounded.

Дослідження можливості використання нейронних мереж при випробуваннях гідравлічних передач тепловозів

The possibility of developing a self-diagnostics system of the diesel locomotives hydraulic transmissions information-measuring test system is researched. The use of neural networks and fuzzy logic for the development of a self-diagnostics system of the diesel locomotives hydraulic transmissions information-measuring tests system is proposed. As the initial stage of developing a diagnostic system using neural networks, a neural network is presented which predicts the rotational speed of the hydraulic turbine wheel during run-time tests. For this purpose, a three-layered, fully permeable perceptron is constructed. This perceptron allows to predict the last 24 seconds of rotation of the hydraulic transmission turbine wheel shaft in run-out mode based on the previous 48 seconds with a fairly high accuracy. Such a developed neural network can be used as part of a self-diagnostic subsystem of the diesel locomotives hydraulic transmissions information-measuring test system and in tests of transmissions in run-out mode when the sensor D2-MMU-2 is used.

Energy analysis of dual-flow hydromechanical gears

Two-flow hydromechanical transmissions are becoming increasingly common in the construction of modern land transport and traction machines (tractors, automobile and high-speed crawler vehicles). This is mainly due to the desire to increase the efficiency of transmission. In order to select a dual-flow hydromechanical transmission scheme in relation to specific operating conditions, it is necessary to know the advantages and disadvantages of various schemes, their potential capabilities. The evaluation of the operation of each circuit can be made on the basis of their kinematic, power, and energy analysis. The results of the kinematic and force analysis of two-flow hydromechanical gears were previously developed by the authors of this article. In energy analysis, the following estimated parameters were used to compare the performance of the transmission: г|ГМП - efficiency of transmission; РМ - power factor in the mechanical branch of the transmission; РН - power factor on the pump wheel of the torque converter; РТ - the power factor on the turbine wheel of the torque converter. The paper considers 12 schemes of two-flow hydrome-chanical gears with a differential link at the input and output with mixed gear coupling, the results of their energy analysis are given. For each of the schemes considered, analytical dependencies of the estimated parameters on the internal parameters of the hydromechanical transmission were obtained, which were used as the characteristic k of the planetary gear set, the power transfer ratio йгт of the torque converter, and the kinematic gear ratio игмп of the hydromechanical transmission. The results of calculations performed on a computer using the external characteristic of a specific torque converter are obtained and presented in graphical form. The obtained results can be used in developing recommendations for the choice of a two-flow hydromechanical transmission scheme.

Composite materials for impellers of the turbocharger of automotive engines

The aim of this work is the search and selection of components of composite materials are fully meeting the requirements imposed to the materials of the impellers of the turbocharger. During the work modern components of the composites and their properties is described. The requirements to materials of impellers were formulated. Patent search was carried out to describe existing concepts of impellers made of composite materials. A possible production version of the impellers is described, revealed their advantages and disadvantages. In the course of patent studies have not traditional the advantages of using composites in the design of the turbocharger. Described the possibility of creating a rotor of the electric machine of the compressor impeller by weaving a copper wire. The main technology of manufacture of impellers is described. Given domestic and foreign manufacturers of polymer matrixes and fibers. The described physic-mechanical properties of randomly reinforced composite materials available on the market today. A comparative analysis of selected composite material most fully meets the requirements - polyamideimide filled carbon fiber. The use of continuous fibers in the impellers is an effective way to increase the strength of the latter. It is established that as a cheaper alternative to polyamideimide can be a carbon-containing material '^^11!" provided reinforcement of the wheel with continuous fibers. Cheap and widely used materials (filled polyamides, polycarbonates, epoxy resin, etc.) can be used in the manufacture of impellers in centrifugal blowers with manual or electric drive. Composites with carbon fiber in silicon carbide matrix (C-SiC) can act as an alternative to heat-resistant nickel alloys, of which currently produce the turbine wheel.