Abstract Combined cycle power plants (CCPP) have many advantages compared to other fossil power plants: high efficiency, flexible operation, compact design, high potential for combined heat and power (CHP) applications and fewer emissions. However, fuel costs are relatively high compared to coal. Nevertheless, major qualities such as high operation flexibility and low emissions distinctly increase in relevance in the future, due to rising power generation from renewable energy sources. An accelerated start-up procedure of CCPPs increases the flexibility and reduces the NO x -emissions, which are relatively high in gas turbine low load operation. Such low load operation is required during a cold start of a CCPP in order to heat up the steam turbine. Thus, a warm-keeping of the thermal-limiting steam turbine results in an accelerated start-up times as well as reduced NO x -emissions and lifetime consumption. This paper presents a theoretical analysis of the potential of steam turbine warm-keeping by means of hot air for a typical CCPP, located in China. In this method, the hot air passes through the steam turbine while the power plant is shut off which enables hot start conditions at any time. In order to investigate an improved start-up procedure, a physical based simplified model of the water-steam cycle is developed on the basis of an operation data set. This model is used to simulate an improved power plant start-up, in which the steam turbine remains hot after at least 120 hours outage. The results show a start-up time reduction of approximately two-thirds in comparison to a conventional cold start. Furthermore, the potential of steam turbine warm-keeping is discussed with regards to the power output, NO x -emissions, start-up costs and lifetime consumption.

This paper discusses the impact of inlet flow distortions on centrifugal compressors based upon a large experimental data base in which the performance of several impellers in a range of corrected flows and corrected speeds have been measured after been coupled with different inlet plenums technologies. The analysis extends to centrifugal compressor inlets including a side stream, typical of Liquefied Natural Gas (LNG) applications. The detailed measurements allow a thorough characterization of the flow field and associated performance. The results suggest that distortions can alter the head by as much as 3% and efficiency of around 1%. A theoretical analysis allowed to identify the design features that are responsible for this deviation. In particular, an extension of the so-called “reduced-frequency”, a coefficient routinely used in axial compressors and turbine aerodynamics to weigh the unsteadiness generated by upstream to downstream blade rows, allowed to determine a plenum-to-impeller reduced frequency that correlates very well with the measured performance. The theory behind the new coefficient is discussed together with the measurement details, and validate the correlation that can be used in the design phase to determine the best compromise between the inlet plenum complexity and impact on the first stage.

The overall cooling effectiveness, which represents the distribution of dimensionless temperature on gas turbines surface, is an important parameter for conjugate heat transfer analysis of gas turbines. Generally, it is difficult to measure the overall cooling effectiveness in engine condition. However, the overall cooling effectiveness can be measured in the laboratory by matching the appropriate parameters to those of the actual turbine blade. Thus, it is important to evaluate the key parameters of matching methods. In this paper, the effects of adiabatic film effectiveness and Biot number on the overall cooling effectiveness were investigated with an impingement/effusion model by numerical simulation, in which 3-D steady RANS approach with the k–ω SST turbulence model were used. The tested plate had 8 cylinder hole rows of 30 degree inclined angle, and the internal cooling employed staggered array jet impingements. The matching performance was evaluated by comparing the results in both typical engine condition and laboratory condition. The analogy principles were discussed in detail, the results showed that the overall cooling effectiveness can be matched by using different matching principles in different lab condition. The theoretical analysis was verified by numerical results. The distribution and values of overall cooling effectiveness can be matched well between engine condition and lab condition by matching both temperature ratio, mainstream side Biot number and blowing ratio. If the temperature ratio is mismatched, the momentum flux ratio will be an important parameter for overall cooling effectiveness. Matching momentum flux ratio will reduce the difference of the adiabatic cooling effectiveness and heat transfer ratio between engine condition and laboratory condition.

Large turbine bearings are usually equipped with hydrostatic jacking mechanisms to separate bearing and shaft during transient start-stop procedures. They are turned off once hydrodynamic operation is reached. In some cases, under severe operating conditions, the hydrostatic oil supply is kept running although the rotor already runs in full speed. The supplied amount of jacking oil is very small compared to the regular oil supply. However, experimental data of a large tilting-pad bearing shows that this hybrid operation has a considerable impact on the load carrying capacity in terms of lower pad temperature and larger film thickness. In this paper, a theoretical investigation to analyse the effect of increased load carrying capacity of a large tilting-pad journal bearing in hybrid operation is presented. The increase is driven by three different aspects: 1) hydrostatic pressure component, 2) increase in lubricant viscosity due to the injection of cold oil, 3) decrease of temperature gradients and thus thermal pad deformation. Subject of the approach is a ø500 mm five-pad, rocker-pivot tilting-pad journal bearing in flooded lubrication mode. The experiments are carried out on the Bochum test rig for large turbine bearings. The theoretical analyses are performed with a simulation code solving the Reynolds and energy equations for the oil film and calculating the thermomechanical pad deformations simultaneously. By considering each of the three above aspects separately and in combination, their share of load increase can be assessed individually. Contrary to expectations, the results indicate that the increase is not mostly based on the hydrostatic pressure component. Instead, the advantageously decreased pad deformations make the largest contribution to the increased load carrying capacity while the alteration in viscosity shows the least impact.

Impact of the diverging cup angle of a swirling injector on the flow pattern and stabilization of technically premixed flames is investigated both theoretically and experimentally with the help of laser diagnostics. Recirculation enhancement with a lower position of the internal recirculation zone and a flame leading edge protruding further upstream in the swirled flow are observed as the injector nozzle cup angle is increased. A theoretical analysis is carried out to examine if this could be explained by changes of the swirl level as the diffuser cup angle is varied. It is shown that pressure effects need in this case to be taken into account in the swirl number definition and expressions for its variation through a diffuser are derived. They indicate that changes of the swirl level including or not the pressure contribution to the axial momentum flux cannot explain the changes observed of the flow and flame patterns in the experiments. The swirl number without the pressure term, designated as pressure-less swirl, is then determined experimentally for a set of diffusers with increasing quarl angles under non-reacting conditions and the values found corroborate the predictions. It is finally shown that the decline of axial velocity and the rise of adverse axial pressure gradient, both due to the cross section area change through the diffuser cup, are the dominant effects that control the leading edge position of the internal recirculation zone of the swirled flow. This in turn is used to develop a model for the change of this position as the quarl angle varies that shows good agreement with experiments.

Experimental results correlating combustion instability and staging ratio in a RP-3 fueled lean premixed pre-vaporized (LPP) combustor is presented. All the experiments are operated at high-pressure and high-temperature conditions, and processed data has been collected and classified by the staging ratio. A low-frequency oscillation is found in the conditions that the main stage and pilot stage work together. There are two discrete frequencies laying in 50∼120 Hz and 420∼470 Hz, the former changes with staging ratio (SR) while the latter remains constant. Sensitivity analysis of flame model reveals that the low-frequency oscillation at 50∼120 Hz is highly suspected to be caused by an intrinsic mode of this combustor. RANS simulation of flame structure finds that delay time could be extended by decreasing SR, which is consistent with the theoretical analysis.

A promising flow analytical way to offset the respective shortcomings for the experimental measure and numerical simulation methods is presented. First, general topological rules which are applicable to the skin-friction vector lines on the passage surface, to the flow patterns in the cross-section of the cascade as well as on the blade-to-blade surface were deduced for the turbomachinery cascades with/without suction/blowing slots in this paper. Second, the qualitative analysis theory of the differential equation was used to investigate the distribution feature of the flow singular points for the limiting streamlines equation. The topological structure of the flow pattern on the cascade passage surfaces was discussed in detail. Third, the experiment and numerical simulations results for a linear compressor cascade passage with highly-loaded compound-lean slotted blade, which were combined to topologically examine the flow structure with penetrating slot injections through the blade pressure side and suction side. The results showed that the general topological rules are applicable and effective for flow diagnosis in highly-loaded compressor blade passage with slots. Finally, an integrated vortex control model, in which the blade compound-lean effect and the injection flow through the slots were coupled, was presented. The model shows that reasonable slot injection configurations can effectively control the concentrated shedding vortices from the suction surface of a highly-loaded compressor cascades passage, thereby the aerodynamic performance for the blade passage is remarkably improved. The present work provides a novel theoretical analysis method and insights of the flow for the turbine blade passage with cooling structures, aspirated compressor blade passage and other applications with new flow control configurations in turbomachinery field.

Air often flows into compressors with inlet prewhirl, because it will obtain a circumferential component of velocity via inlet distortion or swirl generators such as inlet guide vanes. A lot of research has shown that inlet prewhirl does influence the characteristics of components, but the change of the matching relation between the components caused by inlet prewhirl is still unclear. This paper investigates the influence of inlet prewhirl on the matching of the impeller and the diffuser and proposes a flow control method to cure mismatching. The approach combines steady three-dimensional Reynolds-averaged Navier-Stokes (RANS) simulations with theoretical analysis and modeling. The result shows that a compressor whose impeller and diffuser match well at zero prewhirl will go to mismatching at non-zero prewhirl. The diffuser throat gets too large to match the impeller at positive prewhirl and gets too small for matching at negative prewhirl. The choking mass flow of the impeller is more sensitive to inlet prewhirl than that of the diffuser, which is the main reason for the mismatching. To cure the mismatching via adjusting the diffuser vanes stagger angle, a one-dimensional method based on incidence matching has been proposed to yield a control schedule for adjusting the diffuser. The optimal stagger angle predicted by analytical method has good agreement with that predicted by computational fluid dynamics (CFD). The compressor is able to operate efficiently in a much broader flow range with the control schedule. The flow range, where the efficiency is above 80%, of the datum compressor and the compressor only employing inlet prewhirl and no control are just 25.3% and 31.8%, respectively. For the compressor following the control schedule, the flow range is improved up to 46.5%. This paper also provides the perspective of components matching to think about inlet distortion.

Pre-swirl nozzle is regarded as an important part of preswirl system. Theoretical analysis shows that the temperature drop of pre-swirl system directly relates to the pre-swirl effectiveness of nozzle. When the inlet and outlet pressure are given, there are three ways to improve the nozzle pre-swirl effectiveness. Firstly, increase the discharge coefficient by optimizing the geometry of nozzle; secondly, decrease the preswirl angle; thirdly, minimize the deviation angle of outlet flow to decrease the actual throat area and then increase the tangential velocity. A new kind of pre-swirl nozzle called vane shaped hole (VSH) nozzle was presented and designed in this paper. The vane height/ pitch ratio of VSH nozzle could be adjusted to an appropriate value, which made its performance of acceleration and deflection better than that of cascade vane nozzle. With the same throat area, radial location and pre-swirl angle (15°), the performance of VSH nozzle was numerically analyzed and compared with three other traditional ones at pressure ratio range 1.1∼1.9, and Reynolds number range 1×10 5 ∼5×10 5 . The three traditional nozzles were the simple drilled nozzle, aerodynamic nozzle and cascade vane nozzle. To consider the mixing and rotating influence in the pre-swirl cavity downstream of nozzle, the rotating pre-swirl cavity and receiver hole were included in the computational models. Entropy generation analysis was also made for each nozzle to assess the source of irreversibility. Numerical results show that the discharge coefficient of aerodynamic nozzle increase 13.7% compared with that of simple drilled nozzle owing to the smaller pressure gradient at nozzle inlet. For cascade vane nozzle, pressure gradient generated in the course of acceleration and deflection would decrease due to the well-designed vane profile. The discharge coefficient of cascade vane nozzle can be as high as 0.97, whereas the preswirl effectiveness is only 0.86 because of a large deviation angle ( 2.42°). For VSH nozzle, higher vane height/pitch ratio and close to zero trailing edge radius lead to a further decrease of endwall secondary flow loss and trailing edge loss, which results in a very small deviation angle ( 0.56°). Consequently, the pre-swirl effectiveness of VSH nozzle is about 8% higher than that of cascade vane nozzle, though the discharge coefficient is about 5% lower. Since the volume of solid block in VSH is bigger than the volume of vane in cascade vane nozzle, which could reduce the difficulty in manufacturing but increase the total weight. Thus, the final nozzle design should comprehensively consider the aerodynamic performance, cost, manufacturing, and stress constraints.

As a component of delivering cooling air to turbine rotor blade at appropriate pressure, temperature and mass flow rate, pre-swirl system is very important to the cooling of turbine blades. It is attractive to the designers and scholars for its potential ability to reduce relative total temperature of cooling air as large as 100K. A pre-swirl system is actually an aero-thermodynamic system with energy transformation between work and heat. Theoretical analysis was carried out on an isentropic pre-swirl system to deduce equations for ideal temperature drop and power consumption. For an actual pre-swirl system, correlation between the actual temperature drop and power consumption was deduced, and a temperature drop effectiveness was defined also. Theoretical analysis shows that the system’s temperature drop increases linearly with the reduction of the power consumption. Numerical models were derived from a real engine pre-swirl system with small simplification. Standard k-ε turbulence model and Frozen-Rotor approach were applied in the three dimensional steady simulations. Inlet total pressure and total temperature, outlet static pressure, mass flow rate delivered to the blade and rotating speed of rotor were kept to be fixed for all the models. The influences of heat transfer and sealing flow coming from the inner seal were ignored in the simulations. Section averaged parameters like pressure, swirl ratio and total enthalpy were presented at each typical station throughout the flow path. The relationship between the temperature drop and the power consumption of all the models has been verified to be consistent with the deduced formula. For the pre-swirl system with low radial location of nozzle, these measures, such as adding impellers in the cover-plate cavity and inclining the receiver hole, were taken to reduce the power consumption and enlarge the temperature drop obviously. For this specific pre-swirl system, models with high radial location of nozzle are more recommended to decrease the loss caused by the large circumferential velocity difference between the airflow and the rotor.

The segmented carbon seal is regularly used for sealing bearing chambers of aeronautical turboengines or as part of a buffer seal in space turbopumps. The seal operates with contaminated air or with an inert gas and is made of many identic carbon segments (generally three or six) with reciprocally overlapping ends. The segments are serrated against the rotor by the pressure difference between the upstream and the downstream chambers and by a circumferential (garter) spring. The pressure difference and an axial spring press the segments also against the stator. The inner cylindrical surface of each segment is provided with pads that create an aerodynamic lift proportional to the rotor speed. Following this lift force, the segments of the seal are pushed away from the rotor and the seal opens. The contact between the rotor and the segments is lost and an axial leakage path is thus created. Although it was developed since long, a model for calculating the characteristics of the segmented seal is completely absent from the scientific literature. The goal of the present work is to fill this gap at least for the static characteristics (leakage and torque). The analysis is carried out for a single segment of the seal by supposing that all the segments have the same characteristics. Each segment has a planar motion (i.e. three degrees of freedom) and therefore the film thickness under each pad is not uniform. Given the stationary operating conditions (pressure difference and rotation speed), the present model calculates the equilibrium position of each segment on the bases of the lift and of the friction force acting on the pads, of the friction forces acting on the nose of the seal and of the radial and axial springs. Once found the static equilibrium position, the leakage and the torque of the seal are calculated. A parametric study enlightens the importance of the pad waviness, of the pocket depth and of the spring forces on the characteristics of the segmented seal.

In the turbo-compressor driving system, working fluid of large capacity and high pressure is stored in the system. Once an accident happened unexpectedly, the driving power of the rotor would be shut off quickly. Owing to the pressure difference between the inlet and the outlet of the compressor, the original downstream fluid might flow back from the volute to the impeller. The backflow might propel the impeller rotating reversely compared with its working status. It would damage the bearing and sealing system. Therefore, it is necessary to avoid the rotor reversal. With the development of the economies of scale, the capacity of the compressor unit becomes larger and larger, the possibility of the rotor reversal accident might be in consideration. The reverse performance of the centrifugal impeller is related to the mass flowrate of the backflow, the backflow pressure, moment of inertia as well as the initial working rotating speed of the rotor. In order to get the quantitative relation of the parameters, a test rig was set up with a centrifugal fan. The parameter was tested on the idle processes with different initial rotating speeds. Compared with the idle process, the reduction processes of the rotating speed driven by the backflow were tested. The processes varied with the pressure and the flowrate of the backflow. In addition, three-dimension simulation on the fan was performed. Corresponding to the experimental data, numerical performance of the fan was got to verify the numerical method. The flow information in the fan with backflow was analyzed. Even the backflow passing through the impeller, there is small flowrate to the volute by the operating fan. Combined with experimental data and the numerical parameters, the theoretical analysis on the reduction process of rotating speed was carried out. The critical values of the initial working rotating speed, the pressure and the flowrate of the backflow were derived to avoid the reverse rotation. Therefore, it can be used for the fan system in the design process to prevent the reverse rotation.

As a mainstream dynamic dry classifer, the turbo air classifier is widely used in powder preparation industries for its adjustable cut size, controllable product granularity and high classification performance. As an important indicator for evaluating the classification performance of a turbo air classifier, cut size is often predicted in advance to evaluate classification effect so that the operation parameters can be adjusted suitably according to the production requirement. There are two common ways to obtain cut size of turbo air classifiers. One is based on a theoretical formula; another is based on an experimentally derived formula. There are a few problems with the aforementioned ways of predicting cut size. The theoretical analysis often has some large deviations from the actual values. Analysis based on empirical formula can obtain an accurate predicted cut size at the cost of a large number of training samples. In this paper, a new strategy is introduced to determine the cut size based on numerical simulation of gas-solid two-phase flow in the turbo air classifier using ANSYS ® CFX, Release 15.0. The three-dimensional Reynolds-averaged Navier-Stokes equations along with the k-ε turbulence model are adopted to describe the gas flow, and the Lagrangian particle tracking technique is used to calculate the particle trajectory. According to its definition, cut size can be obtained by means of analyzing the particle trajectory. The effects of rotor cage rotational speed and particle density on cut size are also obtained based on analysis of the change of cut size. The simulation results are validated against the experimental data. Numerical simulation provides a new way to obtain the cut size of a turbo air classifier and serves as a method to regulate the operating parameters for classification. It also provides a reference method to study the cut size of various types of classifier.

The oil lubricated multi-leaf foil bearing is developed to meet the demand of high rotating speed for hydraulic turbo-pump, where the lubricated oil is easy to obtain. For the stability of this kind oil lubricated foil bearing needs to be guaranteed, the bearing with elastic supported bump foil structure is proposed to improve the performance of foil bearing. Theoretical analysis and numerical simulation is carried out in this paper. The film thickness expression of multi-leaf foil bearing is established for the cases with and without top foil deformation. The total flexibility matrix considering elastic supported bump foil structure is developed based on Castigliano’s theorem. By employing the Reynolds boundary condition, the oil cavitation effect is presented. The established flexibility matrix is substituting into classical incompressible Reynolds equation, then the deformation equation of the foil and Reynolds equations are solved coupling by successive over relaxation method. The static characteristics such as pressure distribution, bearing load and static equilibrium position are obtained. By employing the perturbation method to Reynolds equations and foil deformation equation, the dynamic characteristics of multi-leaf foil bearing with elastic supported bump foil structure are acquired. The stability of the bearing is analyzed and compared with other type bearings by Routh-Hurwitz method. The effects of bearing load and sommerfeld parameter on the stiffness and damping coefficients are studied. The results indicate that the performance of foil bearing with elastic supported bump foil structure is improved and this kind bearing is suitable for high rotating speed application.

This paper studies the unsteady aerodynamics of vibrating airfoils in the low reduced frequency regime with special emphasis in its impact on the scaling of the work per cycle curves using an asymptotic approach (Part I) and numerical simulations (Part II). A perturbation analysis of the linearized Navier-Stokes equations for real modes at low reduced frequency is presented and some conclusions are drawn. The first important result is that the loading of the airfoil plays an essential role in the trends of the phase and modulus of the unsteady pressure caused by the vibration of the airfoil. For lightly loaded airfoils the unsteady pressure and the influence coefficients scale linearly with the reduced frequency whereas the phase departs from π/2 and changes linearly with the reduced frequency. As a consequence the work-per-cycle scales linearly with the reduced frequency for any inter-blade phase angle and it is independent of its sign. For highly loaded airfoils the unsteady pressure modulus is fairly constant exhibiting only a small correction with the reduced frequency, while the phase departs from zero and varies linearly with it. In this case only the mean value of the work-per-cycle scales linearly with the reduced frequency. This behavior is independent of the geometry of the airfoil and the modeshape in first approximation. For symmetric cascades the work-per-cycle scales linearly with the reduced frequency irrespectively of whether the airfoil is loaded or not. Simulations using a frequency domain linearized Navier-Stokes solver have been carried out on a low-pressure turbine airfoil section, the NACA0012 and NACA65 profiles and a flat plate to show the generality and correctness of the analytical conclusions (Part II of the corresponding paper). Both, the traveling-wave and influence coefficient formulations of the problem are used in combination to increase the understanding and explore the nature of the unsteady pressure perturbations.

The present work is focused on the pneumatic hammer instability in an aerostatic bearing with shallow recesses and orifices of four different diameters. Operating conditions were zero rotation speed, zero load and different supply pressures. The diameters of the tested orifices were large compared to the usual practice and correspond to a combined inherent and orifice restriction. The theoretical analysis was based on the CFD evaluation of the ratio between the recess and the feeding pressure and on the “bulk flow” calculation of the rotordynamic coefficients of the aerostatic bearing. Calculations showed an increase of the direct stiffness with decreasing the orifice diameter and increasing the supply pressure and, on the other hand, a decrease toward negative values of the direct damping with decreasing the orifice diameter. These negative values of the direct damping coefficient indicate pneumatic hammer instabilities. In parallel, experiments were performed on a floating bearing test rig. Direct stiffness and damping coefficients were identified from multiple frequency excitations applied by a single shaker. Experiments were performed only for the three largest orifices and confirmed the decrease of the direct damping with the orifice diameter and the supply pressure. The identification of the rotordynamic coefficients was not possible for the smallest available orifice because the aerostatic bearing showed self-sustained vibrations for all feeding pressures. These self-sustained vibrations are considered the signature of the pneumatic hammer instability. The paper demonstrates that aerostatic bearings with shallow recesses and free of pneumatic hammer instabilities can be designed by adopting orifice restrictors of large size diameter.

Variable inlet prewhirl is an effective way to suppress compressor instability. Compressors usually employ a high degree of positive inlet prewhirl to shift the surge line in the performance map to a lower mass flow region. However, the efficiency of a compressor at high inlet prewhirl is far lower than that at zero or low prewhirl. This paper investigates the performances of a centrifugal compressor with different prewhirl, discusses the mechanisms thought to be responsible for the production of extra loss induced by high inlet prewhirl and develops flow control methods to improve efficiency at high inlet prewhirl. The approach combines steady three-dimensional Reynolds average Navier-Stockes (RANS) simulations with theoretical analysis and modeling. In order to make the study universal to various applications with inlet prewhirl, the inlet prewhirl was modeled by modifying the velocity condition at the inlet boundary. Simulation results show that the peak efficiency at high inlet prewhirl is reduced compared to that at zero prewhirl by over 7.6 percentage points. The extra loss is produced upstream and downstream of the impeller. Severe flow separation was found near the inlet hub which reduces efficiency by 2.3 percentage points. High inlet prewhirl works like a centrifuge gathering low-kinetic-energy fluid to hub, inducing the separation. A dimensionless parameter C is defined to measure the centrifugal component of flow. As for the extra loss produced downstream of the impeller, the flow mismatch of impeller and diffuser at high prewhirl causes a violent backflow near the diffuser vanes’ leading edges. An analytical model is built to predict diffuser choking mass flow which proves that the diffuser flow operates outside of stable conditions. Based on the two loss mechanisms, hub curve and diffuser stager angle were modified and adjusted for seeking higher efficiency at high prewhirl. The efficiency improvement of a modification of the hub is 1.1 percentage points and that of the combined optimization is 2.4 percentage points. During optimizing, constant distribution of inlet prewhirl was found to induce reverse flow at the leading edge of the blade root, which turned out being uncorrelated with blade angle. By revealing loss mechanisms and proposing flow control ideas, this paper lays a theoretical basis for overcoming the efficiency drop induced by high inlet prewhirl and for developing compressors with high inlet prewhirl.

The theoretical analysis, design, and experimental study of a high-speed combustion chamber are described. Such a burner may be used when the compressor outflow speed is so high that diffusion to the usual burner entrance conditions presents severe loss penalties. The study showed for a small mass flow-high pressure ratio turbomachine, that combined diffusor and combustor losses are minimum for a burner entrance Mach number of about 0.5. To design the burner a finite rate chemistry and turbulent mixing computer program was used; the combustor modeling and flame spread predictions are discussed. A series of experiments are described and burner pressure loss and temperature profiles are shown over a range of burner air-flow conditions.

Liquid Piston Pumps are considered to be systems involving the up and down oscillations of a fluid column contained in a vessel which is enclosed at the top. At the bottom a suitable arrangement of check valves converts the oscillatory motion to a pumping action. The oscillations may be generated by cyclic heating, inertia forces, or combinations of the two. Existing designs of LPP’s are reviewed. Experimental results, and a theoretical analysis, are given for a straight tube L.P.P. The design of a Solar LPP is presented, which appears to be a practical and simple means of converting heat energy from a solar panel to potential energy of a water reservoir.

Theoretical analysis and experiments were carried out on cylindrical oil squeeze film dampers. The finite element method (FEM) was applied for calculating pressure distribution in the dampers with end seals and oil grooves. Measurements of the viscous damping coefficient of several dampers were conducted and compared with theoretical values. The effects of the dampers on the vibrational characteristics of engines were reviewed through theoretical analysis and experiments on an engine model. Then, the effects of squeeze film dampers on an actual engine were evaluated for design information.