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Nekrasov A.,OJSC Power Machines
Proceedings of the ASME Turbo Expo | Year: 2013

In the investigated high pressure steam turbine, with increasing steam flow rate the exciting aerodynamic forces rise and cause high, but limited vibration of turbine bearings. The tilting-pad journal bearing load and load angle are changing as the steam flow rate changes in turbine with partial arc admission, and accordingly the dynamic characteristics of bearings change. The field experiments results at fossil fuel power plant presented. The aim of experiments was the partial arc steam admission optimization to reducing the effect associated with change of bearing load/load angle. At first, conventional (consecutive) order of valve opening was investigated. In this case, the bearing vibrations are rising while steam flow and valve outlet pressure are increasing. At some "critical point" the vibration level rises stepwise. Situation repeats symmetrically during turbine unloading/loading. In the second part of experiments, the consecutive order of valve opening was changed to "diagonal" one. As a result, the bearing vibration weakly depends on the steam flow rate and its value is significantly lower. Long-term turbine operation shows that "diagonal" steam admission is optimal for this type of turbine. From the analysis of the forces vectors follows that the "critical point" corresponds to static force, which acts in the direction between neighbor tilting-pads. It is contrary to operation and idle modes where this force is acting on pad. The static steam force is bigger and bearing loading is lower at the "critical point". Numerical investigation of rotor-bearing threshold stability was performed for different bearing loading conditions with exciting aerodynamic steam forces. Two configurations of bearings were included into the model: LBP and LOP - at the "critical point". Consecutive and so-called "diagonal" orders of valve opening were modeled. Threshold capacity is higher for the "diagonal" valve opening order. Copyright © 2013 by ASME. Source


Dolganov A.,OJSC Power Machines | Nekrasov A.,Lita Inc
Proceedings of the ASME Turbo Expo | Year: 2013

Modern large capacity steam turbine for fossil power plants should have a high efficiency to be competitive in today's tough market. It should be compact, with a smaller mass for reducing cost. In these circumstances, an effective solution is to create a large capacity steam turbine that consists of integrated highintermediate- pressure turbine (HIPT) and one low-pressure turbine (LPT). Greater heat drop as compared to a conventional turbine shall be provided in LPT of such steam turbine. With this rather high efficiency of the low-pressure turbine should be provided . The performance of LPT depends not only on the efficiency of trans-and supersonic stages, but also on the efficiency of subsonic upstream stages. At a time when the overall heat drop in the low-pressure turbine is increased, role of the upstream subsonic stages also increases, provided that the design of stages L-0 and L-1 is maintained. This paper presents results of numerical simulation of an optimized subsonic stages section for a new low-pressure steam turbine. Simulation results of a conventional subsonic stages section are presented for comparison. Stages of the optimized subsonic section have a number of features: increased disposable heat drop, enlarged relative pitch, spline representation of sections of blade profiles, 3D airfoil design. The comparison of normalized integral basic characteristics, plots of the main parameters on the blade height, diagrams of the normalized pressure in individual cylindrical sections is given for optimized and conventional cases. Copyright © 2013 by Solar Turbines Incorporated. Source


Lebedev A.,OJSC Power Machines | Simin N.,OJSC Power Machines | Grinevich V.,OJSC Power Machines
Proceedings of the ASME Turbo Expo | Year: 2010

Our company has tested annular combustion chamber, being one of main components of hot gas path for GTE-65 gas turbine in mid power class. In order to arrange gaseous fuel oxidation process a method of lean homogenized air-fuel mixture burning is realized in the combustor. The same type two-contour burner modules are installed on the combustor cap in two rows by 60 burners in a row (120 burners in all). To optimize control algorithm and confirm main performances a model compartment, representing 1/12 part (segment) of actual combustion chamber, was produced. The tests have been conducted with using GP "Ivchenko-Progress" and OJSC "Power Machines" test rigs on modes from ignition to full load. Stable firing mode and pollutant emissions have been determined and the liner temperature condition and temperature field unevenness have been checked. The combustor control algorithm was optimized. As a result of the conducted tests there were confirmed environmental requirements to the combustor NOx emissions (less than 25 ppm). Mathematical simulating machine was being used to predict the combustor operation performances at the gas turbine operating in field conditions. 3D numerical analysis was carried out to predict the temperature and NOx fields before the experiment preparation. In order to meet the numerical model with the test conditions after the experiment the boundary conditions were specified (fuel / air temperature and mass flow rate) Full and partial load calculations were performed for simulation and field operation conditions. The calculation results were compared with experimental data obtained in the course of bench test. Errors obtained by comparison with numerical and experimental data were as follows:• full model pressure drop: ∼ 3-4%; • ratio of peripheral and radial non-uniformities of temperature fields: ∼ 2%; • nitrogen oxides at various operation modes: maximum 25 ppm. The obtained results make it possible to go on the combustor testing in field conditions. Copyright © 2010 by ASME. Source


Krivonosova V.,OJSC Power Machines | Lebedev A.,OJSC Power Machines | Simin N.,OJSC Power Machines | Zolotogorov M.,JSC NPO CKTI | Kortikov N.,Saint Petersburg State Polytechnic University
Proceedings of the ASME Turbo Expo | Year: 2011

This paper presents the results of experimental and numerical investigations of cooling effectiveness of the film cooled turbine nozzle. The nozzle is with two internal cavities. Front cavity of the nozzle is fed with high pressure cooling air from compressor diffuser with minimal losses of pressure for ensuring film cooling of the leading edge. Rear cavity is with impingement tube for high effective convective cooling. Experimental measurements of cooling flow capacity and cooling effectiveness were carried out on experimental facility of OSC "NPO CKTI". Investigations included isothermal internal flow tests and hot tests with internal flow and metal temperature measurements. Test results were compared with flow and thermal field CFD predictions. Temperature fields of body and platforms of nozzle were predicted by conjugate heat transfer simulation. Computation domain includes vane-to-vane path flow, vane solid body with shrouds and holes for cooling air injection. Heat transfer conditions inside vane were calculated with one dimension internal flow model. Isothermal internal flow test results were used to validate one dimension internal flow model. Comparison of the experimental and simulation results enabled to modify calculation models to obtain good agreement. Turbine vane temperature fields calculations in different operation conditions were carried out with validated numerical models. Copyright © 2011 by ASME. Source


Kolesnikov A.,OJSC Power Machines | Nikiforov A.,OJSC Power Machines
IOP Conference Series: Earth and Environmental Science | Year: 2014

Spherical valves are supplied for high-head turbines. The drive of spherical valves designed and manufactured by Power Machines/LMZ provides opening by means of servomotors, and closing under the action of the moment created by counterweights. Selection of parameters for the spherical valve and its design are based on the assumption continuity of the water flow entering the turbine through the penstock. In case, when two or more hydro-units are installed at the HPP, the penstocks usually have pipe bifurcations (Fig.1). The design of the penstock should provide a uniform supply of water to all units without spin, rupture of continuity and pulsation. Given in the paper is an example of the HPP with two (2) hydro-units equipped with inlet spherical valves. In the course of operation valve rotor oscillations with different periods in time (T 15 sec.) were detected. When analyzing, no faults in the valve design and its mechanism of operation were detected. In the course of the tests, vibration parameters of the spherical valves were determined in the following operating conditions: each of the hydro-units running separately and both of them running simultaneously for different power output values. Based on the test results, operating conditions with maximum vibration of were located. The reasons of surging of perturbing forces acting on the rotor of the spherical valve were detected in the course of analysis of the penstock design. Possibility of accumulation of air at the penstock pipe bifurcations was found. When the air transported by the water achieved its critical value, this air appeared to be the cause of instability in the valve operation. The attention was drawn to necessity of taking into account this circumstance when designing penstock pipe bifurcations. © Published under licence by IOP Publishing Ltd. Source

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