Improvement of Aerodynamic and Strength Characteristics of a Multi-Shaft Axial Turbine of a Turboshaft Engine

The article presents the results of solving the complex task of increasing the rotor wheel strength factor and the efficiency of the twin-shaft axial turbine of the small turboshaft engine using methods of multidisciplinary optimization. This turbine consists of a single-stage compressor turbine (CT) and a free turbine (FT). An analysis of the original variant of the turbine revealed that the strength factor of their rotor wheels are significantly lower than the necessary structural requirement. To eliminate the occurring problem at the first step the initial task of estimation the rotor wheels only on the basis of structural requirements was performed without taking into account aerodynamic processes. As a result, variants of the turbine rotor wheels were obtained to provide the structural constraints. They were used as starting points for the complex task of optimization, taking into account aerodynamic and deformation processes. The task of multi-disciplinary CT and FT optimization was solved step by step. As a first step, specific CT and FT models were built, which as a result of their optimization allowed to ensure acceptable strength factor of rotor wheel and slightly increased turbine efficiency. In the next step, a joint model of both turbines was built and tested. Its analysis showed that mutual influence of these working processes of the turbines leads to a distortion of the flow temperature distribution in the flow path, which causes a reduction of the FT blades strength criteria to an unacceptable level. Further optimization of the joint turbine model, taking into account aerodynamic and deformation processes, made it possible to increase the efficiency of both turbines by 0.4% (for each one), providing the necessary safety margins for the disks.

Numerical experiment of flow in stages of inflow turbine with fractional blading of the rotor wheel

В данной работе рассматриваются особенности течения потока в проточной части центростремительной малорасходной турбины с частичным облопачиванием рабочего колеса. Такие турбины относятся к конструктивному классу турбин так называемого безвентиляционного типа. В связи с тем, что рабочие лопатки содержатся не на всей окружности рабочего колеса, а при этом сопла в сопловом аппарате размещены по всей окружности, то это обстоятельство оказывает очень большое влияние на характер течения потока в сопловом аппарате. Прежде всего, особенности работы соплового аппарата заключаются в том, что при вращении рабочего колеса сопла работают в режиме периодического открытия и закрытия, чего не наблюдается у турбин традиционного типа. А такие режимы работы сопел неизбежно отражаются на характере течения потока в них и на величине потерь кинетической энергии. В связи с этим, возникает задача по проведению численного эксперимента на базе программного комплекса вычислительной гидродинамики с необходимостью определения поля скоростей в проточной части турбины в условиях периодического открытия и закрытия крайних сопел. В работе используется метод численного моделирования трехмерного течения потока в среде программного комплекса вычислительной гидродинамики. В качестве основной наиболее подходящей модели используется – нестационарная модель URANS. В ходе проведенного исследования были получены следующие результаты работы: поле числа Маха в проточной части турбины на различных режимах открытия и закрытия сопла, значения коэффициента скорости соплового аппарата, и коэффициента полезного действия турбинной ступени. This paper discusses the flow features in the flow channel of an inflow low-consumption turbine with fractional blading of the rotor wheel. Such turbines belong to the design class of turbines of the so-called non-ventilation type. Due to the fact that the rotor blades are not contained on the entire pitch circle, while the nozzles in the nozzle diaphragm are placed around the entire circuit, this circumstance has a great influence on the flow regime in the nozzle diaphragm. First of all, the features of the nozzle diaphragm are that during the rotor wheel rotation the nozzles operate in the repetitive opening and closing mode, which is not observed in traditional type turbines. And such nozzles operating modes inevitably affect the regime of its flow and the kinetic energy loss. Thereby, a numerical experiment was conducted on the basis of the computational fluid dynamics software package with the need to determine the velocity field in the flow channel of the turbine in the conditions of periodic opening and closing of the extreme nozzles. This paper discusses uses the method of numerical simulation of three-dimensional flow using the of the computational fluid dynamics software package. The most suitable model is the non – stationary URANS model. In the course of the experiment, the following results were obtained: the Mach number in the flow channel of turbine on different modes of opening and closing the nozzle, the value of the speed coefficient of the nozzle diaphragm, and efficiency of turbine stages.

Testing the performance characteristics of specific profiles for applications in wind turbines

The publication presents the results of aerodynamic characteristics of selected profile blades for applications in wind turbines. Considering the potential of energy resources and investors’ preferences, the amount of energy produced in wind farms in the total amount of electricity generated will be systematically growing and probably, in the next few years, wind energy will be the first in the field of electricity production from all types of power plants. Harnessing the power of moving air masses is now a global phenomenon. Rotor wheel converts wind energy into mechanical energy when using blades with chosen shape and oriented in the terms of the optimum performance. The aim of the measurements was to determine the impact of blade shape and blade angle of attack on the efficiency of conversion of wind energy into mechanical energy on the rotor wheel. The obtained power coefficients were presented as results.

Simulation of the joint effect of rotor-stator interaction and circumferential temperature unevenness on losses in the turbine stage

The article devotes to problems of unsteady interaction of the hot streams downstream of the combustion chamber with the rotating blades of the rotor wheel. The hot streams downstream of the combustion chamber are caused by discrete circumferentially located fuel nozzles and openings for air supply to the combustion chamber mixing zone. Unsteady interaction of the hot streams with the rotating blades of the rotor wheel leads to local redistribution of the time average gas flow temperature which has effect on the blade – “temperature segregation”.

Simulation of the joint effect of rotor-stator interaction and circumferential temperature unevenness on losses in the turbine stage

The article devotes to problems of unsteady interaction of the hot streams downstream of the combustion chamber with the rotating blades of the rotor wheel. The hot streams downstream of the combustion chamber are caused by discrete circumferentially located fuel nozzles and openings for air supply to the combustion chamber mixing zone. Unsteady interaction of the hot streams with the rotating blades of the rotor wheel leads to local redistribution of the time average gas flow temperature which has effect on the blade – “temperature segregation”.

A Three-Dimensional Computational Study of Pulsating Flow Inside a Double Entry Turbine

The double entry turbine contains two different gas entries, each feeding 180 deg of a single rotor wheel. This geometry can be beneficial for use in turbocharging and is uniquely found in this application. The nature of the turbocharging process means that the double entry turbine will be fed by a highly pulsating flow from the exhaust of an internal combustion engine, most often with out-of-phase pulsations in each of the two entries. Until now research on the double entry turbine under pulsating flow conditions has been limited to experimental work. Although this is of great value in showing how pulsating flow will affect the performance of the double entry turbine, the level of detail with which this can be studied is limited. This paper is the first to use a three-dimensional computational analysis to study the flow structures within a double entry turbine under conditions of pulsating flow. The analysis looks at one condition of pulsating flow with out-of-phase pulsations. The computational results are validated against experimental data taken from the turbocharger test facility at Imperial College and a good agreement is found. The analysis first looks at the degree of mass flow storage within different components of the turbine and discusses the effect on the performance of the turbine. Each of the volute limbs is found to be subject to a large degree of mass storage throughout a pulse cycle demonstrating a definite impact of the unsteady flow. The rotor wheel shows a much smaller degree of mass flow storage overall due to the pulsating flow; however, each rotor passage is subject to a much larger degree of mass flow storage due to the instantaneous flow inequality between the two volute inlets. This is a direct consequence of the double entry geometry. The following part of the analysis studies the loss profile within the turbine under pulsating flow using the concept of entropy generation rate. A significant change in the loss profile of the turbine is found throughout the period of a pulse cycle showing a highly changing flow regime. The major areas of loss are found to be due to tip leakage flow and mixing within the blade passage.

A 3-Dimensional Computational Study of Pulsating Flow Inside a Double Entry Turbine

The double entry turbine contains two different gas entries, each feeding 180° of a single rotor wheel. This geometry can be beneficial for use in turbocharging and is uniquely found in this application. The nature of the turbocharging process means that the double entry turbine will be fed by a highly pulsating flow from the exhaust of an internal combustion engine, most often with out of phase pulsations in each of the two entries. Until now research on the double entry turbine under pulsating flow conditions has been limited to experimental work. Although this is of great value in showing how pulsating flow will affect the performance of the double entry turbine, the level of detail with which this can be studied is limited. This paper is the first to use a 3 dimensional computational analysis to study the flow structures within a double entry turbine under conditions of pulsating flow. The analysis looks at one condition of pulsating flow with out of phase pulsations. The computational results are validated against experimental data taken from the turbocharger test facility at Imperial College and a good agreement is found. The analysis first looks at the degree of mass flow storage within different components of the turbine and discusses the effect on the performance of the turbine. Each of the volute limbs is found to be subject to a large degree of mass storage throughout a pulse cycle demonstrating a definite impact of the unsteady flow. The rotor wheel shows a much smaller degree of mass flow storage overall due to the pulsating flow, however each rotor passage is subject to a much larger degree of mass flow storage due to the instantaneous flow inequality between the two volute inlets. This is a direct consequence of the double entry geometry. The following part of the analysis studies the loss profile within the turbine under pulsating flow using the concept of entropy generation rate. A significant change in the loss profile of the turbine is found throughout the period of a pulse cycle showing a highly changing flow regime. The major areas of loss are found to be due to tip leakage flow and mixing within the blade passage.

Heavy Truck Hub and Wheel-Off Accidents: A Mechanical Analysis

Hub retention is the foundation of wheel retention. The hub attaches securely to the spindle or axle tube. The brake drum, brake rotor, wheel and tire all mount to the hub. If the hub comes off of the spindle or axle tube, the driver and other motorists are faced with a potentially dangerous situation. This paper will analyze the phenomenon of hub loss and subsequent wheel-off accidents by using the analysis of several of the author’s most recent investigations. The analyses will describe the mechanics of the system, how it functions, its failure modes, preventative measures and an alternative design which can mitigate this phenomenon from occurring. Specifically, this paper is focused on the phenomenon related to the rotational dynamics of wheels on the left side of the vehicle unwinding the spindle nut(s)—allowing for the loss of the entire wheel end assembly.