0


Article

J. Eng. Gas Turbines Power. 2000;122(4):505. doi:10.1115/1.1323232.
Abstract
Topics: Ice
Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS—SPECIAL ICE SECTION: Engine Design

J. Eng. Gas Turbines Power. 2000;122(4):506-519. doi:10.1115/1.1290592.

Power cylinder friction is a major contributor to overall engine friction. For engines of the future to become more fuel efficient it will be necessary to reduce power cylinder friction. To be able to reduce the friction it is important to fully understand it. This paper is a review of power cylinder friction with a specific emphasis on diesel engines. This paper first describes how significant the contribution of power cylinder friction is compared to all the other losses of the engine. It compares the mechanical friction of the engine to the total energy produced by the engine. Then a comparison is made of the power cylinder friction to overall mechanical friction. A comparison of different methods of friction measurement is be made. The advantages and disadvantages are given for each method. There is also a comparison of motoring versus firing friction tests. An equation is given to estimate the effect of bore and stroke on power cylinder friction. Other equations for estimating power cylinder friction are also shown. More sophisticated cylinder kit models are reviewed. Finally a review is made of methods for reducing friction. These are based on a broad review from various companies. [S0742-4795(00)01604-5]

Topics: Friction , Engines , Cylinders
Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1999;122(4):520-525. doi:10.1115/1.1286674.

Durability is very important for current diesel engines. Diesel engine manufacturers are trying to make the engines live as long as possible before overhaul. The time to overhaul for an engine is usually dictated by high oil consumption or blowby. Therefore, it is necessary to understand how wear affects the cylinder kit dynamics, oil consumption, and blowby in an engine. This paper explores the effect of power cylinder component (rings and cylinder bore) wear by using a cylinder kit dynamics model. The model predicts how wear will affect ring motion, inter-ring gas pressure, blowby, etc. The parameters studied were: liner wear, ring face wear, and ring side wear. Two different engines were modeled. The characteristics of these two engines are very different. As a result, the effects of wear are different and the corresponding durability will be different. This illustrates the need to model each individual type of engine separately. The modeling shows that top ring face wear is very significant for maintaining good oil and blowby control. Liner wear is important, but does not have as large an effect as ring wear. The effects of side wear are significant for these two cases. [S0742-4795(00)00203-9]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1999;122(4):526-532. doi:10.1115/1.1290593.

The paper presents an original probabilistic model of the balance of internal combustion engines. The model considers the manufacturing tolerances and predicts the most probable value of the first-order residual unbalance for engines that—theoretically—have the first order forces and moments balanced. It has been found that, assuming normal distributions of the geometric and mass parameters of the reciprocating mechanisms of a multicylinder engine, the unbalancing forces and moments are statistically distributed according to a Rayleigh law. The mode of the Rayleigh distribution, which represents the most probable value of the residual unbalance, is expressed in terms of the statistical characteristics of the parameters subjected to manufacturing tolerances. In this way, the tolerances and, especially the ones admitted for the reciprocating masses, are directly correlated to the expected value of the residual unbalance making it possible to establish reasonable limits for these tolerances. Validation of the probabilistic balance model is demonstrated by computer simulation. [S0742-4795(00)01704-X]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS—SPECIAL ICE SECTION: Intake and Exhaust System Dynamics

J. Eng. Gas Turbines Power. 1998;122(4):533-540. doi:10.1115/1.1288706.

Recently a new TVD scheme was presented by the authors and a comparison was made with other algorithms for two engine related test cases (the shock tube and the tapered pipe). It was shown that the new scheme combines high accuracy with exact conservation of the mass flow, even in tapered pipes. In this paper the pressure waves in the inlet and exhaust system of a single cylinder engine are measured and compared to calculations with the new algorithm. The comparison is made under motoring and firing conditions of the engine with two different external mixture formation systems (different fuels: gasoline and methane). Modifications on intake and exhaust pipe configuration clearly show their influence on the pressure wave development. The importance of the loss coefficients for the flow through the inlet and exhaust valves (mass flow coefficient) is demonstrated. A test rig has been built to obtain these coefficients under steady-state conditions as a function of valve lift and mass flow rate. It is shown that for this engine configuration the measured steady-state loss coefficients are not reliable at low valve lifts. This can be explained by the influence of the Reynolds number and the appearance of a transition zone. For all mentioned comparisons the agreement is excellent. The next phase will be to evaluate the code for multi-cylinder engines under atmospheric and turbo-charged conditions. [S0742-4795(00)00204-0]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):541-548. doi:10.1115/1.1288771.

A comparison of different numerical algorithms used in commercial codes for the calculation of the one-dimensional unsteady flow in the pipes of the inlet and exhaust systems of internal combustion engines is presented in this work. The comparison is made between the Method Of Characteristics (MOC), different Lax-Wendroff schemes, first order upwind schemes and the newest TVD (Total Variation Diminishing) schemes. These algorithms are representative for the complete evolution noticed in the computer codes from the beginning of their use to the present state of the art. Two models of realistic problems in engine simulation tasks are considered: the shock tube calculation (so called Sod’s problem) and the calculation in a tapered pipe. The first test case simulates the exhaust valve opening and releasing a pressure (shock)wave in the exhaust manifold while the other test case covers any gradual variation in the cross section of the manifold pipes. For both test cases computed results are compared with an exact solution and computer time and accuracy are evaluated. None of the examined schemes is completely satisfactory. They either show too much overshoots (for the first test case), or they have local discretization errors (at the section changes of the second test case). A new TVD scheme is proposed that does not introduce any of the foregoing inaccuracies. With this scheme overshoots and dips are eliminated and mass balances are fulfilled, while maintaining high accuracy. [S0742-4795(00)00304-5]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):549-555. doi:10.1115/1.1290589.

The modelling of wave propagation in complex pipe junctions is one of the biggest challenges for simulation codes, particularly those applied to flows in engine manifolds. In the present work an inviscid two-dimensional model, using an advanced numerical scheme, has been applied to the simulation of shock-wave propagation through a three-pipe junction; the results are compared with corresponding schlieren images and measured pressure-time histories. An approximate Riemann solver is used in the shock-capturing finite volume scheme and the influence of the order of accuracy of the solver and the use of adaptive mesh refinement are investigated. The code can successfully predict the evolution and reflection of the wave fronts at the junctions whilst the run time is such as to make it feasible to include such a model as a local multi-dimensional region within a one-dimensional wave-action simulation of flow in engine manifolds. [S0742-4795(00)01304-1]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):556-561. doi:10.1115/1.1289387.

A four-stroke four-cylinder turbocharged engine can be fitted with two different types exhaust system: a simple common manifold fed by all cylinders, or a twin-branch manifold, where two selected cylinders, directed by the firing order, feed two separate turbine entries. In this case good utilization of the exhaust pressure pulse energy can be achieved at higher loads and lower engine speeds, leading to good overall turbocharger efficiency and favorable pressure distribution during the gas-exchange period. Improved engine scavenging capability affects quality and quantity of the fresh charge and consequently influences the exhaust gas emissions. If, in addition, valve overlap period is increased the benefit of this system is still more evident. Common manifold exhaust system shows its advantage through lower pumping losses at higher engine speeds and lower loads. Both systems were optimized and the results of numerical and experimental work are presented in the paper. [S0742-4795(00)00404-X]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):562-569. doi:10.1115/1.1290587.

This paper presents the SELENDIA code designed for the simulation of marine diesel engines. Various measured and simulated results are compared for the performance of a sequentially turbocharged marine diesel engine during a switch from one to two turbochargers. The results show a good agreement between measured and simulated data. Surge loops that are experimentally observed in case of an anomaly are analyzed using simulated results. Finally, the predictive capabilities of the simulation code are utilized to investigate the influence of the inlet manifold volume on the engine and air charging system performance with a special focus on compressor surge. [S0742-4795(00)01104-2]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS—SPECIAL ICE SECTION: In-Cylinder Processes

J. Eng. Gas Turbines Power. 2000;122(4):570-578. doi:10.1115/1.1290149.

Intake flow structure was studied using various port geometries in a four-valve heavy-duty diesel engine. Swirl ratio, LDV measurements of bulk flow and turbulence, and flow visualization experiments were conducted on a steady-state bench rig. In addition to the standard production port, archetypal intake port flows (swirl, anti-swirl and tumble) were created using intake valve shrouds. These flow types are not usually found in heavy-duty engines, which typically employ quiescent combustion chamber designs. However, recent CFD analyses have indicated that intake flow structures can significantly influence engine pollutant emissions (Fuchs and Rutland, 1998). Thus, it was of interest to characterize these flows in a heavy-duty engine. The measured swirl and axial velocity components were analyzed to reveal the swirl and tumble generation mechanisms, and the LDV data compared favorably with the swirl meter results. The flow visualization confirmed the existence of flow recirculation regions under the intake valves also seen in the LDV data. These flow structures help to explain the origins of the overall swirl and tumble flow fields. The results were also compared with available CFD predictions made using the same port configurations. The measured swirl levels were found to agree with the CFD trends. However, in some cases quantitative differences were found, presumably due to the effect of piston motion in the actual engine. These differences need to be accounted for when evaluating port designs from steady-flow measurements, especially in cases with high tumble flow components. [S0742-4795(00)00804-8]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):579-587. doi:10.1115/1.1290588.

LDV measurements have been taken in a disc chamber four-stroke reciprocating engine under motoring conditions. Two non-simultaneous velocity components have been recorded at three different locations on the mid-plane of the TDC clearance during the intake and compression strokes for three different speeds (600, 800, 1000 rpm). The locations are characterized by different flow conditions (near the intake valves; on the cylinder axis; near the exhaust valves). The combination of different engine speeds and different chamber locations enables one to look both at the global behavior of the flow and at the details of the turbulence time-evolution. The aim of the research is to identify the frequency which can be considered a separation between “true” turbulence and cycle-by-cycle variation of the mean flow and to analyze the variation of such a frequency with the measuring location and with the engine speed. The analysis has been carried out by using different tools: the non-stationary velocity autocorrelation function, the power spectrum and the cycle-resolved analysis based on the frequency filter. The various approaches offer complementary perspectives of the same phenomenon, which give a clear perception of the physical meaning of the most frequently used investigation tools. The results show that the cut-off frequency increases as the engine speed increases and as the measuring point moves away from the ordered jet coming out of the intake valves. [S0742-4795(00)01204-7]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1999;122(4):588-595. doi:10.1115/1.1290591.

The performance of two spray models for predicting liquid and vapor fuel distribution, combustion and emissions is investigated. The model predictions are compared with extensive data from in-cylinder laser diagnostics carried out in an optically accessible heavy-duty, D. I. diesel engine over a wide range of operating conditions. Top-dead-center temperature and density were varied between 800 K and 1100 K and 11.1 and 33.2 kg/m3, respectively. Two spray breakup mechanisms were considered: due to Kelvin-Helmholtz (KH) instabilities and to Rayleigh-Taylor (RT) instabilities. Comparisons of a wide range of parameters, which include in-cylinder pressure, apparent heat release rate, liquid fuel penetration, vapor distribution and soot distribution, have shown that a combination of the KH and the RT mechanisms gives realistic predictions. In particular, the limited liquid fuel penetration observed experimentally was captured by including these two competing mechanisms in the spray model. Furthermore, the penetration of the vapor fuel ahead of the liquid spray was also captured. A region of high soot concentration at the spray tip was observed experimentally and also predicted by the KH-RT spray breakup model. [S0742-4795(00)01504-0]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):596-602. doi:10.1115/1.1288705.

This investigation was conducted to enhance understanding of combustion in a direct injection (DI) diesel engine with square combustion chamber. The investigation included a bench study of spray and its interaction with the chamber and correlation with engine performance. The bench study was conducted by using a liquid injection technique (LIT). The technique relies on the use of instantaneous photo images of emulsified fuel spray patterns to deduce spray behavior. It captures spray images in forced swirling flow on a positive film, which was used to deduce fuel-air mixing by scattering radiation technique. Three different chamber configurations, with different ratios of arc radius (r) to inscribed circle radius (R), and several spray deflecting angles were used in the study. The best parameters were found to be a deflecting angle of about 30 deg and a ratio of r/R of about 0.65. The results of the bench test were used to compare engine performance at similar design parameters. The engine performance was found to be superior at the above values of r/R and the deflecting angle. Engine exhaust of NOx and exhaust smoke were found to be lower at these design parameters. The experimental technique of using emulsified spray with LIT can be used qualitatively to evaluate effects of combustion chamber and fuel system design variables on engine performance. [S0742-4795(00)00104-6]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS—SPECIAL ICE SECTION: Alternative Fuels Combustion and Emissions

J. Eng. Gas Turbines Power. 1999;122(4):603-610. doi:10.1115/1.1290585.

Recent testing of exhaust emissions from large bore natural gas engines has indicated that formaldehyde (CH2O) is present in amounts that are significant relative to hazardous air pollutant standards. In consequence, a detailed literature review has been carried out at Colorado State University to assess the current state of knowledge about formaldehyde formation mechanisms and evaluate its applicability to gas engines. In this paper the following topics from that review, which bear directly on formaldehyde formation in natural gas engines, are discussed: (1) post combustion equilibrium concentrations; (2) chemical kinetics; (3) flame propagation and structure; (4) partial oxidation possibilities; and (5) potential paths for engine out formaldehyde. Relevant data taken from the literature on equilibrium concentrations and in-flame temperatures and concentrations are presented in graphical form. A map of possible paths for engine out formaldehyde is used to summarize results of the review, and conclusions relative to formation and destruction mechanisms are presented. [S0742-4795(00)00904-2]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 1999;122(4):611-616. doi:10.1115/1.1290586.

Current research shows that the only hazardous air pollutant of significance emitted from large bore natural gas engines is formaldehyde (CH2O). A literature review on formaldehyde formation is presented focusing on the interpretation of published test data and its applicability to large bore natural gas engines. The relationship of formaldehyde emissions to that of other pollutants is described. Formaldehyde is seen to have a strong correlation to total hydrocarbon (THC) level in the exhaust. It is observed that the ratio of formaldehyde to THC concentration is roughly 1.0–2.5 percent for a very wide range of large bore engines and operating conditions. The impact of engine operating parameters, load, rpm, spark timing, and equivalence ratio, on formaldehyde emissions is also evaluated. [S0742-4795(00)01004-8]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):617-623. doi:10.1115/1.1289386.

This paper presents the results from an internal research study conducted at the Southwest Research Institute (SwRI) on the effects of stoichiometric mixtures of natural gas and synthesis gas with exhaust gas recirculation (EGR) on engine performance and exhaust emissions. Constant load performance and emissions tests were conducted on a modified, single-cylinder, Caterpillar 1Y540 research engine at 11.0 bar (160 psi) bmep. Engine performance and emissions comparisons between natural gas with EGR, and natural gas with syngas and EGR are presented. In addition, the performance characteristics of the fuel reforming catalyst are presented. Results show that thermal efficiency increases with increasing EGR for both natural gas operation and natural gas with syngas operation at constant load. The use of syngas with natural gas extended the EGR tolerance by 44.4 percent on a mass basis compared to natural gas only, leading to a 77 percent reduction in raw NOx emissions over the lowest natural gas with EGR NOx emissions. [S0742-4795(00)00504-4]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):624-631. doi:10.1115/1.1289385.

With the exception of rape seed oil which is the principal raw material for biodiesel Fatty Acid Methyl Esters, (FAME) production, sunflower oil, corn oil, and olive oil, which are abundant in Southern Europe, along with some wastes, such as used frying oils, appear to be attractive candidates for biodiesel production. In this paper fuel consumption and exhaust emission measurements from a single cylinder, stationary diesel engine are described. The engine was fueled with fuel blends containing four different types of biodiesel, at proportions up to 100 percent; the further impact of the usage of two specific additives was also investigated. The four types of biodiesel appeared to have equal performance and irrespective of the raw material used for their production, their addition to the traditional diesel fuel improved the particulate matter emissions. The results improve further when specific additive combinations are used. [S0742-4795(00)00604-9]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Ceramics

J. Eng. Gas Turbines Power. 2000;122(4):632-636. doi:10.1115/1.1287584.

Plasma-sprayed mullite (3Al2O3⋅2SiO2) and mullite/yttria-stabilized-zirconia (YSZ) dual layer coatings have been developed to protect silicon-based ceramics from environmental attack. Mullite-based coating systems show excellent durability in air. However, in combustion environments, corrosive species such as molten salt or water vapor penetrate through cracks in the coating and attack the Si-based ceramics along the interface. Thus the modification of the coating system for enhanced crack-resistance is necessary for long-term durability in combustion environments. Other key durability issues include interfacial contamination and coating/substrate bonding. Interfacial contamination leads to enhanced oxidation and interfacial pore formation, while a weak coating/substrate bonding leads to rapid attack of the interface by corrosive species, both of which can cause a premature failure of the coating. Interfacial contamination can be minimized by limiting impurities in coating and substrate materials. The interface may be modified to improve the coating/substrate bond. [S0742-4795(00)03203-8]

Commentary by Dr. Valentin Fuster
J. Eng. Gas Turbines Power. 2000;122(4):637-645. doi:10.1115/1.1287492.

Statistical methods for the design of ceramic components for time-dependent failure modes have been developed that can significantly enhance component reliability, reduce baseline data generation costs, and lead to more accurate estimates of slow crack growth (SCG) parameters. These methods are incorporated into the Honeywell Engines & Systems CERAMIC and ERICA computer codes. Use of the codes facilitates generation of material strength parameters and SCG parameters simultaneously, by pooling fast fracture data from specimens that are of different sizes, or stressed by different loading conditions, with data derived from static fatigue experiments. The codes also include approaches to calculation of confidence bounds for the Weibull and SCG parameters of censored data and for the predicted reliability of ceramic components. This paper presents a summary of this new fatigue data analysis technique and an example demonstrating the capabilities of the codes with respect to time-dependent failure modes. This work was sponsored by the U.S. Department of Energy/Oak Ridge National Laboratory (DoE/ORNL) under Contract No. DE-AC05-84OR21400. [S0742-4795(00)02103-7]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Coal, Biomass, and Alternative Fuels

J. Eng. Gas Turbines Power. 2000;122(4):646-650. doi:10.1115/1.1287491.

The Power Systems Development Facility (PSDF) is a Department of Energy (DOE) sponsored engineering scale demonstration of two advanced coal-fired power systems. Particulate cleanup is achieved by several High Temperature, High Pressure (HTHP) gas filtration systems. The PSDF was designed at sufficient scale so that advanced power systems and components could be tested in an integrated fashion to provide confidence and data for commercial scale-up. This paper provides an operations summary of a Siemens-Westinghouse Particulate Control Device (PCD) filtering combustion gas from a Kellogg, Brown, and Root (KBR) transport reactor located at the PSDF. The transport reactor is an advanced circulating fluidized bed reactor designed to operate as either a combustor or a gasifier. Particulate cleanup is achieved by using one of two PCDs, located downstream of the transport reactor. As of the end of 1998, the transport reactor has operated on coal as a combustor for over 3500 h. To date, filter elements from 3M, Blasch, Coors, Allied Signal (DuPont), IF&P, McDermott, Pall, Schumacher, and Specific Surface have been tested up to 1400 °F in the Siemens-Westinghouse PCD. The PSDF has a unique capability for the collection of samples of suspended dust entering and exiting the PCD with Southern Research Institute’s (SRI) in-situ particulate sampling systems. These systems have operated successfully and have proven to be invaluable assets. Isokinetic samples using a batch sampler, a cascade impactor and a cyclone manifold have provided valuable data to support the operation of the transport reactor and the PCD. Southern Research Institute has also supported the PSDF by conducting filter element material testing. [S0742-4795(00)02203-1]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Combustion and Fuel

J. Eng. Gas Turbines Power. 2000;122(4):651-658. doi:10.1115/1.1287164.

This paper reports results of experimental and numerical investigations on ethane-air two-stage combustion in a counterflow burner where the fuel stream, which is partially premixed with air for equivalence ratios from 1.6 to 3.0, flows against a pure air stream. Similar to methane, the two-stage ethane combustion exhibits a green fuel-rich premixed flame and a blue diffusion flame. Flame structures, including concentration profiles of stable intermediate species such as C2H4,C2H2 and CH4, are measured by a gas chromatography and are calculated by numerical integrations of the conservation equations employing an updated elementary chemical-kinetic data base. The implications of the results from these experimental measurements and numerical predictions are summarized, the flame chemistry of ethane two-stage combustion at different degrees of premixing (or equivalence ratio) is discussed, and the relationship between NOx formation and the degree of premixing is established. The present work helps to increase understanding of flame chemistry of hydrocarbon fuels, identify important reactions for pollutant formation and suggest means to reduce emissions. [S0742-4795(00)01303-X]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Controls and Diagnostics

J. Eng. Gas Turbines Power. 2000;122(4):659-663. doi:10.1115/1.1285845.

The development of a “stabilized” temperature sensor has led to significant increases in turbine operating efficiency by maximizing output when compared with present sensor technology. These stabilized type K and E thermocouples are superior to existing standard non-stabilized thermocouples because they are not prone to the typical aging effects in the 400 to 600°C (752 to 1112°F) temperature range that can result in measurements errors. A complete set of 18 stabilized type K thermocouples were installed on the exhaust of several gas turbines used for power generation. These thermocouples were subjected to normal operating conditions for a period of one year. During that year, the increase in turbine output has ranged from 0.5 percent to almost 2.0 percent. This increase in output also translates into significant cost savings. In addition, the stabilized thermocouples have given the turbine maintenance technicians more confidence in the accuracy of their temperature measurements and resulted in improved troubleshooting and decision making. [S0742-4795(00)02502-3]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Cycle Innovations

J. Eng. Gas Turbines Power. 2000;122(4):664-671. doi:10.1115/1.1287346.

The thermoeconomic analysis of gas turbine based cycles is presented and discussed in this paper. The thermoeconomic analysis has been performed using the ThermoEconomic Modular Program (TEMP V.5.0) developed by Agazzani and Massardo (1997). The modular structure of the code allows the thermoeconomic analysis for different scenarios (turbine inlet temperature, pressure ratio, fuel cost, installation costs, operating hours per year, etc.) of a large number of advanced gas turbine cycles to be obtained in a fast and reliable way. The simple cycle configuration results have been used to assess the cost functions and coefficient values. The results obtained for advanced gas turbine based cycles (inter-cooled, re-heated, regenerated and their combinations) are presented using new and useful representations: cost versus efficiency, cost versus specific work, and cost versus pressure ratio. The results, including productive diagram configurations, are discussed in detail and compared to one another. [S0742-4795(00)01903-7]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Heat Transfer

J. Eng. Gas Turbines Power. 2000;122(4):672-679. doi:10.1115/1.1287265.

A five times scale model of an engine brush seal has been manufactured. The bristle stiffness and pressure were chosen to satisfy close similarity of the relevant non-dimensional parameters, and the choice of parameters is described. The comparison of flow characteristics for the model seal and an engine seal confirmed the non-dimensional similarity. Detailed pressure measurements were performed within the bristle pack by employing hollow bristles. This novel measurement allowed insight to be obtained into the operation of both clearance and interference seals. In particular, the measured pressure variation in the region of the bristle tips was significant. The deflection of the bristles was determined by comparing the bristle tip pressures with the static pressures along the shaft. Hence the compaction of the pack in this region was found directly. A numerical modeling of brush seals employing anisotropic flow resistance has been developed. Predictions were compared with the measured pressure distributions within the pack. This enabled sensible selection of the pack resistance distribution to be made. Although uniform anisotropic resistance throughout the pack gave reasonable flow rate characteristics, the pressure distribution was not reproduced. A variation of resistance coefficient consistent with the observed compaction was required to give a solution comparable with the experiments. [S0742-4795(00)01703-8]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Marine

J. Eng. Gas Turbines Power. 2000;122(4):680-684. doi:10.1115/1.1287165.

The Royal Navy (RN) has in-service experience of both marinized industrial and aero derivative propulsion gas turbines since the late 1940s. Operating through a Memorandum of Understanding (MOU) between the British, Dutch, French, and Belgian Navies the current in-service propulsion engines are marinized versions of the Rolls Royce Tyne, Olympus, and Spey aero engines. Future gas turbine engines, for the Royal Navy, are expected to be the WR21 (24.5 MW), a 5 to 8 MW engine and a 1 to 2 MW engine in support of the All Electric Ship Project. This paper will detail why the Royal Navy chose gas turbines as prime movers for warships and how Original Equipment Manufacturers (OEM) guidance has been evaluated and developed in order to extend engine life. It will examine how the fleet of engines has historically been provisioned for and how a modular engine concept has allowed less support provisioning. The paper will detail the planned utilization of advanced cycle gas turbines with their inherent higher thermal efficiency and environmental compliance and the case for all electric propulsion utilizing high speed gas turbine alternators. It will examine the need for greater reliability/availability allowing single generator operation at sea and how by using a family of 3 engines a nearly flat Specific Fuel Consumption (SFC) down to harbour loads can be achieved. [S0742-4795(00)01203-5]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Structures and Dynamics

J. Eng. Gas Turbines Power. 2000;122(4):685-692. doi:10.1115/1.1287264.

This paper describes the experimental application of adaptive control to Hybrid Squeeze Film Damper (HSFD) supported rotors. The HSFD has been shown to be an adaptive damper capable of providing infinite damper configurations between short and long damper configurations. Previously, theoretical investigations of the adaptive control of HSFD concentrated on the development of the model reference adaptive control (MRAC) method, as well as development of a nonlinear reference model. Simulations of the performance of the adaptive controller during run-up and coast-down indicated the superior performance of the adaptive controller. In this paper, the adaptive controller is tested on a multi-mode rotor. A test rig is designed and developed using computer control. A simple reference model is investigated consisting of a second order system. Three forms for adaptation gain are studied. The results of the experimental investigation illustrated the performance capabilities of the adaptive controller applied to the HSFD, and moreover indicated the possibility of simple design for the adaptive controller. [S0742-4795(00)01603-3]

Commentary by Dr. Valentin Fuster

TECHNICAL PAPERS: Gas Turbines: Vehicular and Small Turbomachines

J. Eng. Gas Turbines Power. 2000;122(4):693-698. doi:10.1115/1.1287585.

The core of any hybrid propulsion system is a high power density, low weight, and fuel efficient electric energy producer. The LV100 recuperated turbine engine is such a system. This engine is well suited to provide electric power efficiently at a volume and weight significantly lower than current systems. Originally designed for vehicular use and environment to drive a Hydrokinetic transmission, the turbine’s high output speed lends itself to incorporate into the engine design an advanced generating device. This LV100 engine-based electric energy producer will provide in excess of 1MW of electric power in a volume of under one cubic meter at a weight of about 2500 pounds at fuel efficiencies comparable to advanced vehicular diesel engines. Recent state-of-the-art improvements in materials and component technology will permit further reductions in volume/weight and increase the system fuel efficiency. The technologies required to reach a volume of under one cubic meter, the system performance projections obtainable by technology upgrades and the program achievements to date are discussed. [S0742-4795(00)03103-3]

Commentary by Dr. Valentin Fuster

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In