This paper compares experimental static pressure measurement with CFD simulation in a centrifugal compressor at 12 points through the diffuser. Three mass flow rates are selected, each for three operating speeds giving nine total operating conditions. The results show that the CFD model generally slightly underpredicts the static pressure value as compared to the experimental...

The stability of typical rotating fluid machinery such as single ahd multi-stage pumps is evaluated by using the finite element method. The individual contribution of the impellers, bearings and seals to the stability and the dynamic interactions of these fluid elements are examined. Various types of bearings and seals, such as annular smooth, parallel grooved and damper seals...

Modern rotating machines such as turbomachines, either produce or absorb huge amount of power. Some of the common applications are: steam turbine-generator and gas turbine-compressor-generator trains produce power and machines, such as pumps, centrifugal compressors, motors, generators, machine tool spindles, etc., are being used in industrial applications. Condition-based...

The estimation of a model of the foundation of a rotary machine has been recently attempted by using the difference between two sets of response data at some of the bearing locations from two consecutive rundowns of the machine, with and without known unbalance weights at certain positions on the two balance discs of each rotor respectively. However, it would be a great advantage...

According to popular belief, air temperature effects on wind turbine power output are produced solely by air density variations, and power is proportional to air density. However, some cases have been reported, all involving stall-controlled wind turbines, in which unexpected high power output was observed at very low temperatures.

Gas turbines are extensively used for aircraft propulsion, land-based power generation, and industrial applications. Thermal efficiency and power output of gas turbines increase with increasing turbine rotor inlet temperature (RIT). The current RIT level in advanced gas turbines is far above the .melting point of the blade material. Therefore, along with high temperature material...

In this article case studies are presented involving rotordynamic instability of modern high-speed turbomachinery relating the field data to analytical methods. The studies include oil seal related field problems, instability caused by aerodynamic cross-coupling in high-pressure, high-speed compressors, and hydrodynamic bearing instability resulting in subsynchronous vibration of...

Considerable improvements of machines can be expected in the near future through the use ofelectronics in combination with control techniques. A key position will be held by the actuator systems that finally have to accomplish the controlled energy transfer according to the objectives. For rotating machine parts this is usually done via the bearings. Basically, there are two...

This work details the progress made in the development of aerodynamic models for studying Vertical-Axis Wind Turbines (VAWT's) with particular emphasis on the prediction of aerodynamic loads and rotor performance as well as dynamic stall simulations. The paper describes current effort and some important findings using streamtube models, 3-D viscous model, stochastic wind model...

A naphthalene sublimation technique was employed to study the mass transfer distributions over a turbine blade surface with secondary flows ejected in the spanwise direction through three rows of equally-spaced injection holes located in the leading edge region. The mass transfer measurements were conducted in a range of blowing ratios from 0.6 to 1.2 at two different mainstream...

The paper presents a method for estimation of a multi-bearing machine alignment on the basis of measured eccentricities of the shaft in machine bearings. The method uses a linear FEM model of the rotor and the non-linear models of machine bearings. In the presented example, the non-linear models of hydrodynamic bearings are used, but it is shown, that the method could be easily...

This paper presents a technique for quantifying the wear or damage of gear teeth in a transmission system. The procedure developed in this study can be applied as a part of either an onboard machine health-monitoring system or a health diagnostic system used during regular maintenance. As the developed methodology is based on analysis of gearbox vibration under normal operating...

In the development of an air-turbine with self-pitch-controlled blades for wave energy conversion, existence of hysteretic characteristics in a reciprocating flow has been examined. In order to clarify the validity of the analysis, a numerical simulation has been made by use of the experimental results obtained from a steady unidirectional flow condition. The comparison between...

Naphthalene sublimation technique and the heat/mass transfer analogy are used to determine the detailed local heat/mass transfer distributions on the leading and trailing walls of a twopass square channel with smooth walls that rotates about a perpendicular axis. Since the variation of density is small in the flow through the channel, buoyancy effect is negligible. Results show...

The vortex model of propellers is modified and applied to the high-speed horizontal axis turbines. The turbine blades are replaced by lifting lines and trailing vortices which shed along the blade span. The model is not a free wake model, but it is still a nonlinear one which should be solved iteratively. In addition to the regular case where the trailing vortices are constrained...

Cooling of high speed rotating components is a typical situation found in turbomachinery as well as in automobile engines. Accurate knowledge of discharge coefficients and heat transfer of related components is essential for the high performance of the whole engine. This can be achieved by minimized cooling air flows and avoidance of hot spots. In high speed rotating clutches for...

A computer code predicting the flows through the centrifugal compressor with the radial vaneless diffuser was developed and applied to investigate the detailed flowfields, i.e., secondary flows and jet-wake type flow pattern in design and off-design conditions. Various parameters such as slip factors, aerodynamic blockages, entropy generation and two-zone modeling which are...

The transient process which starts at the instability threshold of a rotor rotating in a fluid environment, and ends up in the limit cycle of self-excited vibrations known as fluid whirl or fluid whip, is discussed in this paper. A one-lateral-mode, isotropic, nonlinear model of the rotor with fluid interaction allows for exact particular solutions and an estimation of the...

This paper describes an efficient method to automatize vibration diagnosis for rotating machinery using a decision tree, which is applicable to vibration diagnosis expert system. Decision tree is a widely known formalism for expressing classification knowledge and has been used successfully in many diverse areas such as character recognition, medical diagnosis, and expert systems...

The increased use of small gas turbines and turbochargers in different technical fields has led to the development of highly-loaded centrifugal compressors with extremely thin blades. Due to high rotational speed and the correspondingly high centrifugal loads, the shape of the impeller hub must also be optimized. This has led to a reduction of the thickness of the impeller disc...

This study is to investigate the dynamics of a rotor, with a single degree of freedom (SDOF), mounted on nonlinear bearings. This system has piecewise-linear stiffness and is subjected to a forcing excitation due to residual mass imbalance as well as a parametric one due to an axial periodic thrust. The frequencies for each individual parametric and forcing excitations are not...

Synchronous elimination as one of the possible methods of cancelling any harmful vibration resulting from the unbalance of rotary machines is considered. This method, introduced by Fesca and Thearle, involves the placement of unbalanced elements (e.g. ring, pendulum, ball balancers) on the rotor axis, which can occupy any angular position in relation to the rotor. Under defined...

Numerical calculations on four blade passages are done using Q3D Navier-Stokes solver with a simple mixing length turbulence model and two more advanced transport-equation approaches. Mixing length is simple and cheap but crude, while more sophisticated transport approaches are more physical but more expensive. Predicted results using different turbulent models are discussed and...

The flow field in the stator of a clear torque converter was studied using laser velocimetry. Five planes in the stator were studied at a speed ratio of 0.800 and three planes were studied at a speed ratio of 0.065. Data complements previously available pump and turbine data. Flow in the stator inlet plane is highly non-uniform due to the complicated flow exiting the turbine. At...