Nozzle Blades Research Articles

Gas dynamic optimization of the work process of a single-stage cooled axial turbine with an inside baffle

The article presents the results of optimization of the work process of a single-stage axial turbine in order to increase its efficiency. During optimization, it was necessary to preserve the construction of the original turbine as much as possible. To solve this problem, a parameterization scheme for turbine blades and path contours was developed, taking into account the design and technological limitations. The turbine nozzle blade had an inside baffle. To control the possibility of placing the baffle, a special program was developed that automatically monitors the spatial position of the sections of the blade of the nozzle set. A post-processing program was developed to control the flow parameters at the turbine outlet in height. The efficiency and the vertical deviation of the angle of the outflow from the turbine from the original one were used as optimization criteria. The limitations were the mass flow rate of the working fluid and the total pressure ratio of the turbine. The problem was solved in several stages with different changing variables. As a result of solving the problem, it was possible to increase the turbine efficiency by 0.9%

Influence of Acid Concentration in Combined Cleaning of Gas Turbine Nozzle Blades from Metal Oxides

Influence of Acid Concentration in Combined Cleaning of Gas Turbine Nozzle Blades from Metal Oxides

Drift potential and coverage ratio analysis of an air induction nozzle under an agricultural drone with various operating condition; an indoor test

Delivering pesticides in the agricultural field has been a venturing advancement in the past decades with the aim of target spraying. Agricultural drones have been introduced as useful assets for target spraying, however, the turbulent downwash flow generated by the drone blades accelerates the atomization process that attributes to the drift potential. In this experimental study, the effect of downwash flow on an air induction nozzle is compared to that of a conventional flat fan XR nozzle under various drone operating conditions to evaluate the best working condition. The test was carried out in an indoor facility in which the effect of environmental parameters can be minimized. The 2D patternation of the droplet deposition known as coverage ratio was evaluated using water-sensitive papers with the change of operating conditions, including nozzle type, drone speed, flying height, and blade rotational speed. As the drone flight speed, height, rotational speed, and nozzle position changed, alterations in droplet size and coverage uniformity were observed along with propagation in the drift effect. In addition, the coverage ratio of the AI nozzle was higher than that of the XR nozzle.

Effect of hydrogen on nickel oxide reduction on the surface of nozzle blade of a gas turbine unit

Currently, there is a growing interest in the use of hydrogen in the composition of fuel mixtures for turbojet engines and gas turbine units (GTU). The effect of hydrogen on heat-resistant nickel alloys of gas turbine blades has been little studied. In this regard, this work is devoted to studying the effect of hydrogen on nickel oxide reduction on the surface of the nozzle blade of a gas turbine engine. Hydrogen is a good reducing agent. Therefore, this article discusses the effects of hydrogen under various conditions with metal oxides, and methods of metal oxides reduction on the surface of the blades of a gas turbine engine. The thermodynamics of the interaction of aluminum, titanium, nickel and tungsten oxides with hydrogen fluoride and reactions of fluoride with hydrogen was investigated in the temperature range 273 – 1373 K. It was established that the interaction of aluminum oxide with hydrogen fluoride occurs in the temperature range from 273 to 1073 K, titanium oxide with hydrogen fluoride – from 273 to 373 K, nickel oxide with hydrogen fluoride – from 273 to 873 K. In this case, of the resulting fluorides, only nickel fluoride interacts with hydrogen at temperatures above 673 K. Hydrogen interacts with nickel oxide throughout the entire temperature range, and with tungsten oxide at temperatures above 1173 K. We studied the effect of hydrogen on heat-resistant nickel alloys of gas turbine blades subjected to preliminary fluorination and not treated with fluorine compounds. Nickel oxide reduction with hydrogen proceeds better after the preliminary fluorination process. In this case, particles 2 – 5 μm in size containing 90.16 % Ni are formed on the surface of the blade sample. Without fluorination, this process at 1223 K and duration of 1 h does not occur.

Computational Investigation of Effect of Casing Wall Motion On Flow and Losses in an Annular Turbine Rotor Impulse Cascade

The present paper presents computational results of effect of casing wall motion on three dimensional flow and losses in an annular turbine rotor impulse cascade. The flow at the inlet of the rotor cascade is radially non uniform, which is simulated by means of an upstream nozzle blade row. Commercial CFD software is used for the computations. No slip condition is used for the case of stationary casing, whereas relative wall condition is used for the case of rotating casing. Streamlines, velocity vectors, contours of static pressure on blade tip, contours of total loss coefficient at blade exit, spanwise variation of lift coefficient, circumferentially averaged flow angles and total pressure loss coefficient and axial variation of mass averaged total pressure loss coefficient are presented for both cases. There are minor differences in the spanwise variation of various parameters for both cases. The casing wall motion reduces the losses in the region near to casing but increases in the region far away from the casing. The blade loading and lift coefficient are increased with increase in casing wall motion near the casing and reduced away from the casing. The casing motion causes a slight reduction of losses associated directly with the leakage vortex. However total losses remain nearly same.

“The effect of the nozzle blade pitch on the velocity coefficient of the inflow turbine with partial blading of the runner

A numerical experiment with three groups of low-consumption inflow turbine with partial blading of the runner is considered in the paper. Geometric models of turbine stages with partial flapping of the runner with different grid spacing of the nozzle diaphragm have been developed. The object of this study is centripetal turbine stages with partial flapping of the impeller. The subject of the study is the efficiency coefficient and the velocity coefficient of the nozzles of the inflow turbine. The research method is numerical simulation of the working fluid flow using elements of computational gas dynamics. The aim of the study is to determine the effect of the nozzle blade pitch on the efficiency of the nozzle diaphragm of low-consumption inflow turbine with partial blading of the runner. The main objectives of the study are creating geometric models of turbine stages with different nozzle pitch, determining the boundary conditions of the experiment, conducting and processing the results of the experiment. The graphs of the dependence of the nozzle velocity coefficient and the efficiency of the low-consumption inflow turbine stage are provided. A comparative analysis of the nozzle velocity coefficient and the efficiency coefficient of three turbine stages with different grid spacing of the nozzle diaphragm is carried out. The velocity fields of the flow part of the turbine stages and the integral values of the parameters necessary for the three-dimensional calculation are obtained. The influence of the nozzle blade pitch on the velocity coefficient of the nozzle diaphragm and the efficiency coefficient of the turbine stage is determined. The nature and dependence of this geometric parameter on the efficiency of the study object is established, conclusions on further improvement of turbine stages with partial blading of the runner are made.

Investigation of structural-phase transformations in a foundry structural alloy based on Ni3Al intermetallic compound after high-temperature exposures and during the operation of the alloy as a nozzle blade

The paper presents studies of structural and phase transformations in intermetallic compositions based on the Ni3Al compound depending on alloying and high-temperature treatments, carried out in the process of creating a cast structural alloy for operation in the temperature range of 900–1200°C. Experimentally, when testing the developed intermetallic alloy as nozzle blades of the 1st stage of a high-pressure turbine, it was confirmed that the alloy is thermally stable at temperatures up to 1200°C.

Acoustic preliminary design of a low-noise fan stage considering a variable-area nozzle and variable-pitch rotor blades

A low-noise low-pressure ultra-high-bypass-ratio fan stage to be implemented in the next generation of aircraft engines is described and evaluated acoustically with semi-empirical and analytical methods suited for preliminary design. As expected, good reduction potentials are observed for the jet noise and fan tonal noise components when the UHBR design is compared to current fans in service. However, concerns are identified for fan broadband noise, which are attributed to the off-design operation of the UHBR fan too close from its stability limit. By unloading the fan and thus reducing the size of the rotor wakes, the variable-area nozzle provides a substantial fan broadband noise reduction with a nozzle opened by around 15% from its design value. Alternatively, with the variable-pitch fan, closing the rotor blades by roughly 5° turns out to be an even more effective method to reduce fan noise, as the unloading mechanism is combined with a stronger tilting of the rotor wakes and a lower intra-stage flow Mach number. Opening the nozzle or closing the blades beyond the setting that provides the best fan efficiency is not recommended as the acoustic benefit progressively vanishes, whereas technical feasibility becomes more challenging. Finally, the presence of one of these systems may allow for the design of a low-solidity rotor, with a smaller contribution from the rotor wakes and thus a weaker fan noise emission.

ОСОБЕННОСТИ ПРИМЕНЕНИЯ МНОГОКООРДИНАТНЫХ ШЛИФОВАЛЬНЫХ СТАНКОВ С ЧПУ ДЛЯ ПОВЫШЕНИЯ ПРОИЗВОДИТЕЛЬНОСТИ, КАЧЕСТВА И ТОЧНОСТИ ОБРАБОТКИ ДЕТАЛЕЙ И УЗЛОВ АВИАЦИОННЫХ ГАЗОТУРБИННЫХ ДВИГАТЕЛЕЙ

The paper is aimed at improving the productivity, quality and accuracy of manufacturing gas turbine engine parts and assemblies for the modern growing passenger aviation transport based on the use of technical capabilities of modern multiaxis CNC grinding machining centers. The paper shows the results of successful application of a five-axis CNC grinding machining center MFP-050.65.65 made by Magerle (Switzerland), which allows reducing by five times the number of operations, universal machines, special devices and cutting tools by increasing the number of machined surfaces for one set of nozzle blades of an aviation gas turbine engine. Simultaneously with a significant increase in the productivity of machining various multidirectional surfaces of the nozzle blades due to the use of new highly porous grinding wheels and rational modes of deep grinding, a higher burn-free quality of the ground surfaces is ensured and an important task is solved to increase the accuracy of the flow sections of the turbine nozzle apparatus with the combined use of CNC system and special software for correcting errors of part casting surfaces during their installation, turning and deep grinding of the base surfaces. The developed new technology of nozzle blades machining was introduced for the first time in the Russian Federation at the Aviadvigatel enterprise for manufacturing nozzle blades of modern newly produced gas turbine engines.

Influences of main design parameters on the aerodynamic performance of a micro-radial inflow turbine

The micro-radial inflow turbine (MRIT) is not only an important component of a micro-gas turbine but also the core part of a vehicle exhaust gas turbocharger and a small-scale organic Rankine circulatory system. Therefore, designing an MRIT with good performance is of great importance. The values of some main turbine design parameters can significantly influence its aerodynamic performance and structural size. In accordance with the structural characteristics of an MRIT, the relationships between the aerodynamic performance of a turbine and the absolute flow angle at the rotor inlet, the relative flow angle at the rotor outlet, the nozzle and rotor blade velocity coefficients, the ratio of the wheel diameter, velocity ratios, and the degree of reaction were examined. This was done through theoretical analysis combined with experience in the design of a conventional radial inflow turbine. On this basis, the influencing laws and degrees of the seven main design parameters on the aerodynamic performance of an MRIT during aerodynamic design were analyzed. The selection principles of these main design parameters were also summarized. The reasonableness of the above-mentioned selection principles was verified through an aerodynamic design case study of an MRIT combined with a 3D numerical simulation. It was found that the 3D numerical simulation results agreed well with the 1D aerodynamic design. The summarized selection principles of the main design parameters can provide a reference for the successful aerodynamic design of an MRIT.

Исследование эффективности различных систем охлаждения перспективных газотурбинных двигателей

The paper focuses on foreign and Russian aviation bypass turbojets with an afterburner, studies the design of their turbine cooling systems, and introduces the research findings. For computational research and comparative analysis, we used Russian and foreign samples of advanced bypass turbojets with an afterburner with the most optimal technical characteristics, made calculations of the gas-dynamic parameters of their cooling systems in four critical jet operating modes. In this paper, we introduce the results of hydraulic calculations of various schemes for supplying cooling air to the nozzle and working blades of a high-pressure turbine. Relying on the results of the calculation, we comparatively analyzed the foreign and Russian cooling systems design, in terms of power indicators and efficiency of a gas turbine jet. To do this, we used the following parameters: cooling air bleeding value at maximum jet speed and cruising mode, value of cooling air leakage through the axial gaps into the flow path, the change in the cooling air bleeding value as a percentage of the flow rate through the high-pressure compressor when switching from maximum to cruising mode, i.e. adaptability of the cooling system, the temperature of the cooling air at the point of supply to the cooling cavities of the blade of the nozzle apparatus or the working blade.

DEVELOPMENT AND RESEARCH OF THE TOPOLOGY OF COOLING BAFFLES FOR BLADES OF THE AXIAL CARBON DIOXIDE TURBINES

Currently, there is an increase in average annual temperature and climate change across the various continents. Carbon dioxide emissions from energy facilities contributed to this condition. Implementation of oxy-fuel cycles is a promising solution for reducing carbon dioxide emissions from the energy sector. To date, the most efficient oxy-fuel cycle is the Allam cycle. In this cycle supercritical carbon dioxide acts as a working fluid of the cycle, wherein СО2’s temperature upstream of the turbine is 1,150 °С and the pressure is 30 MPa. Due to the high temperature of the working fluid, it is necessary to cool first stages of the carbon dioxide turbine. The feature of considered cooling system in this turbine is that carbon dioxide being used as a refrigerant too. This paper investigated two topologies of convective cooling systems in the carbon dioxide turbine’s nozzle blade as well as considers an option for increasing the intensity of heatexchange through the use of helical ribbing in the cylindrical cooling baffle. Numerical simulation involving the ANSYS software package was performed for two topologies of the cooling baffles arrangement in the nozzle blade body: configuration 1 -with 17 baffles of 1 mm diameter, configuration 2 -with three baffles of the blade profile shape. Configuration 1 proved to be more efficient: the Nusselt number has a value of 117, and average value of the heat transfer coefficient on the refrigerant side is 6,413 W/m2∙K. The effect of using helical ribbing in the cooling cylindrical baffle of the blade under study was investigated, which enabled to reduce the metal temperature by 54 °С on average and doubled the heat transfer coefficient.

Influence of nozzle clearance of VG turbocharger turbine on performance and internal flow

Abstract To realize a sustainable society, it is necessary to reduce exhaust gas from automobiles and improve fuel efficiency. Turbochargers are useful for the purpose and especially variable geometry (VG) turbochargers are often installed because their nozzle blade angle can be optimally changed according to the rotational speed of the engine. To change the angle, it is needed to provide the nozzle clearance on both hub and shroud sides. In this study, CFD (Computational Flow Dynamics) calculations of a turbocharger turbine were conducted. The rotational speed of the turbine was set to 10,000 rpm. The diameter of the wheel blade is 60 mm and the height of the nozzle blade was 9.71 mm. The following were mainly investigated: the effect of the nozzle clearance position or blade angle on turbine performance, and the effect of leakage vortex from nozzle clearance on the downstream flow in the wheel domain. First, the steady-state CFD analysis on the nozzle and wheel domain was conducted. Four models of nozzle clearance were used: No Clearance (NC), Hub Clearance (HC), Shroud Clearance (SC), and Hub and Shroud Clearance (HSC). And four nozzle blade angles were used. With the Shroud Clearance model, the torque efficiency was worst with every nozzle blade angle. It was also found that the leakage flow rate from the nozzle clearance affects the loss increase in the wheel domain. Second, the unsteady-state CFD analysis on the full domain (casing + nozzle + wheel +diffuser) was conducted to investigate the leakage flow from nozzle clearance. The turbulence model was DES (Detached Eddy Simulation). Hub Clearance model and Shroud clearance model were used. The leakage vortex generated from nozzle clearance was found to flow into the wheel domain. With each nozzle model, the rotating directions of those vortexes were opposite. By the rothalpy loss investigation with the Hub Clearance model, it was confirmed that the portions of wheel domain where two leakage vortexes flow into showed larger losses than other portions. Those portions were located diagonally in two places, and they rotated in the opposite direction to the wheel rotation. On the other hand, with the Shroud Clearance model, the portions where the rothalpy loss was large were not shown regularly.

Flow Characteristics of the Nozzle Blade Cascade in the Mode of the Joint Operation with the Radial Diffuser

The obtained research data are given for the nozzle cascade used by a small-size gas turbine of an average fanning in combination with the radial diffuser. Aerodynamic characteristics of the nozzle blade cascade were determined in a wide range of a change in the Reynolds number varying from 4∙105 to 106 and the reduced velocity varying in the range of 0.4 to 1.13. The flow rate coefficient of the nozzle cascade was derived for all modes using the integral methods and the drainages behind the cascade. The kinetic energy loss coefficient and the flow angles were calculated using the measurement data of flow parameters in three control modes that were obtained due to the use of orientable pneumometric probes. When the expansion degree of the convergent –divergent annular duct behind the cascade is equal to 1.43 the flow in the narrow section of this duct is “enlocked” in the mode when the reduced velocity behind the cascade is equal to 1.127. At such velocity the Reynolds number 106 is self-similar for the flow rate coefficient. At lower values of Reynolds number, the decrease of it is accompanied by an intensive decrease in the flow rate coefficient for all the values of the reduced velocity. For the Reynolds number lower than 7∙105 an increase in the velocity results in a decreased flow rate coefficient. When this number exceeds 8∙105 an increase in the velocity results in an increase of the flow coefficient up to the moment when the flow is “enlocked” in the nozzle cascade.

Optimal design of radial inflow turbine for ocean thermal energy conversion based on the installation angle of nozzle blade

Ocean Thermal Energy Conversion (OTEC), as a new type of renewable energy, has huge development potential. Turbine is the most critical component in the ocean thermal energy conversion system, which directly determines the performance and energy conversion efficiency of the system. Therefore, the optimal design of turbines is very important to improve the efficiency of ocean thermal energy conversion. Based on the full consideration of the small temperature difference application characteristics of ocean thermal energy conversion and the special thermophysical properties of organic working fluids, this paper designs an ammonia working centripetal turbine with a power of 100 kW for OTEC applications, and then analyzes the effect of different geometric parameters on turbine performance. At the same time, the key parameters of the turbine are optimized based on full three-dimensional CFD numerical simulation analysis. It's shown that the nozzle blade installation angle has a very important impact on the performance of the turbine. Through optimization, when the nozzle blade installation angle reaches 30.5°, the efficiency is 91.77%, which is 6.25% points higher than the design value. The internal flow field performance is the best without obvious shock wave and reverse vortex phenomenon, which further improves the efficiency of the turbine and improves the internal flow.

Optimization of the cooling system of the nozzle blade of an energy gas turbine

Optimization of the cooling system of the nozzle blade of an energy gas turbine

Optimal detailed design and performance assessment of natural gas pressure reduction stations system equipped with variable inlet guide vane radial turbo-expander for energy recovery

The turbo-expander system is utilized instead of the pressure regulator to avoid exergy destruction occurring in gas pressure reduction systems. However, due to the variation of natural gas input conditions such as mass flow rate, the sustainable performance of this technology is challenging. In this study, at first, the optimal system design of gas pressure reducing station equipped with radial expansion turbine is performed. It is based on economic and exergy analyses as well as considering geometric, fluid, thermodynamic constraints of components and the systematic constraints. To do so, detailed design models of main components including mean-line design model of radial turbine, mathematical model of heat exchanger and design model of fired heater are developed. Then, the annual proficiency of the optimal system in dynamic conditions was evaluated according to the strategies considered for having stable production. One of the solutions is to improve the turbine efficiency by adjusting the angle of nozzle blades regarding the changes in mass flow rate. Therefore, our developed mean-line off design model of the turbine is applied to adjust inlet guide vane angle in the off-design situation to improve continuous electricity generation. The results of the design section show that the exergy efficiency on this occasion can achieve up to a maximum of 40%. Compared with fix inlet guide vane (IGV), applying variable IGV improves efficiency of turbine up to 60% at off-design condition. The Levelized cost of electricity (LCOE) and payback period of selected optimal design are about 0.0236 $/kWh, and 4 years, respectively. It indicates that this technology could be the economic option compared to other power generation systems.

Использование теории подобия при проектировании турбин газотурбинных двигателей

At present, in the promising development of gas turbine engines compared to at least the fourth generation products, there have been significant changes in the approaches to the design of engine. First of all, it is an increase in maximum values of temperature, gas pressure and circumferential flow speeds, an increase in power of the turbine stage, as well as improvement of the turbine manufacturing technology. All these factors lead to the fact that when designing the flow parts of the gas turbine, it is necessary at the fixed design flow rate of the working medium in the engine, i.e. at the fixed diameters, lengths of the nozzle and rotor blades forming the outline of the inter-blade channels, to increase the blade chords with the corresponding reduction of the number of blades in the row. The increase in turbine stage power associated with the increase in temperature, pressure (density), and circumferential velocity increases the bending stresses leading to the need to increase chords at a fixed blade length. Significant reduction of number of blades in stages, simplifies technology of blades manufacturing. A substantial increase in the maximum gas temperature, in the perspective of more than 2000 K, also leads to the need to increase the blade chords, due to the need to place cooling cavities in the blades. As a result, contradictions arise with the use of similarity theory in the design of stages of turbines of different purpose, as some of the main requirements of similarity are violated — geometric similarity of blade channels of the flow part and then the use of the generally accepted number Re by the chord of blades loses meaning. Therefore, it is necessary to carry out detailed investigations of all flow parameters in four stages of turbines with detection of influence of change of rotor blade chords at equal length of blades. And justify the effect of change of rotor blade chords on physical processes in flow parts of turbines in engines of various purpose.

Model of analysis of the results of geometry scanning of turbine nozzles

The paper presents a mathematical model to perform computer calculation for open flow area of turbine nozzles. The model is used to work with objects in *.stl format when processing data after scanning. Using the developed model, calculations of the part quality parameters will not depend on the controller qualifications, and the proposed approach will not require unique adjustment, costly repair and storage of reference patterns for all sizes of nozzle devices. The calculation was performed in three sections, which improves accuracy while reducing labor intensity and cost of measurement. Increasing the number of sections practically does not affect the labor intensity of calculations, so there are no significant restrictions on performing virtual measurements in four or more sections. The model was implemented in the mathematical package MATLAB. The model was tested with the example of STL processing of the turbine nozzle blades sector.

Methods of increasing the reliability of turbine elements

The purpose of the work. Statistical and experimental analysis of coating methods on the turbine nozzle apparatus to increase the temperature regime.
 Research methods. Calculation method of finite elements, experimental.
 The results obtained. Studies have shown that the use of thermally protective coatings TZP thickness of 250 мm with a thermal conductivity of 1 W / mK on the two steps of the turbine can implement one of two possibilities:
 - at constant operating temperature of the blade material to increase the temperature of the gas in front of the turbine by about 100 °C, which will increase efficiency and fuel savings by more than 13 %;- without changing the temperature of the gas in front of the turbine - to increase the durability of the blades by about 4 times, due to a decrease in their operating temperature. The analysis of two methods of drawing TZP was carried out, in the work the estimation of a temperature condition of the nozzle device (CA) of the turbine of a high pressure of the engine, decrease in its temperature due to drawing TZP and increase of its resource is carried out. The problem was solved by applying TZP on the blades of the nozzle apparatus. The analysis of two methods of drawing TZP was carried out, the estimation of a temperature condition of the nozzle device (CA) of the turbine of high pressure of the engine, decrease in its temperature due to drawing TZP and increase of its resource is carried out.
 Scientific novelty. The problem of creating efficient, economical and reliable gas turbines is the most difficult among the many problems that arise in the development of gas turbine construction. Important elements of turbines are working and nozzle blades, the material and design of which determine the allowable gas temperature in front of the turbine and thus directly affect the technical and economic performance of the gas turbine engine.
 Practical value. The obtained results are important for the further development of aircraft engine construction, due to the application of TZP achieved an increase in the resource of CA from 40,000 hours to 67,000 hours.