A Bladeless Turbocompressor Concept: Shear Driven Gas Compression With Deformable Structures: Part 1 — Experimental Proof of Concept

2017 ◽  
Author(s):  
Hooshang Heshmat ◽  
James F. Walton
Keyword(s):  
Shear Flow ◽  
Parametric Study ◽  
Gas Turbines ◽  
Rotating Disk ◽  
Specific Power ◽  
Proof Of Concept ◽  
Foil Bearings ◽  
Compliant Surface ◽  
Gas Compression ◽  
Smooth Disk

A novel concept for shear flow driven gas compression that could enable next generation turbomachinery has been designed and experimentally demonstrated. In order to achieve this, a prototype proof-of-concept compliant foil-based bladeless turbo-compressor device was developed and used to conduct a gas compression parametric study. The principle underpinning the operation of this device is the conversion of shaft power into hydrodynamically generated pressure that occurs in the shear flow between a smooth rotating disk and a compliant surface. The present compliant foil bladeless turbocompressor (CFBT) is an evolutionary derivative of self-acting compliant foil bearings and seals, which operate in the hydrodynamic regime. Thus, as in these devices, the process of compression induced by shear flow is dominated by the balance between pressure and viscous forces, which are in turn enhanced and controlled by tribological effects arising between the shear layer and the deformable geometry of the compliant surface. The single shaft foil bearing based proof-of-concept CFBT presented is powered by a permanent magnet motor capable of reaching speeds up 360,000 rpm, and consists of two independent compression stages mounted on opposite ends of the shaft. Each compression stage consists of a smooth disk with the effective corresponding counterface of radii 7.6 mm < r < 14.1 mm, with one of each disk’s surfaces facing a four-pad compliant foil surface mounted on the housing. The nominal initial gap separating each of the disks from their corresponding compliant foils is nominally h0 = 0.025 mm and 0.4 mm, respectively. In this configuration, air is entrained from opposite directions through axial intakes and turned 90° as it undergoes shear between the rotating disk and the compliant foil pads of each of the stages, inducing a net radially-oriented outward flow, which is then collected in the quasi-volute of the respective stage. The system is heavily instrumented, with each of the quasi-volutes fitted with thermocouples, pressure probes and a flow meter. An experimental parametric study was performed compressing standard temperature and pressure air for varying speeds up to 360,000 rpm. Performance curves reporting flow vs. pressure as well as compression power requirements vs. speed were obtained for the individual compression stages. The experimental results on the proof of concept turbocompressor are analyzed in the context of the theoretical foundations presented in a companion paper (Heshmat and Cordova, 2017), showing excellent correlation. It is anticipated that due to its simple bladeless geometry, application of this novel technology in conjunction with foil bearings will result in low cost, ultra-high speed, high efficiency, high specific power, miniaturized turbocompressors and high power density oil-free and maintenance-free machines, such as compressors, meso-scale gas turbines, or turbogenerators. Attractive applications for this technology range from military micro-UAV propulsion and portable power systems, to domestic combined heat and power (CHP) turboalternators and medical devices such as portable oxygen concentrators and CPAP (Continuous Positive Air Pressure) machines.

A Bladeless Turbocompressor Concept: Shear Driven Gas Compression With Deformable Structures: Part 2 — Operating Principles and Theory

2017 ◽  
Author(s):  
Hooshang Heshmat ◽  
José Luis Córdova
Keyword(s):  
Shear Flow ◽  
High Speed ◽  
High Efficiency ◽  
Plate Theory ◽  
Operating Conditions ◽  
Fluid Film ◽  
Specific Power ◽  
Compliant Surface ◽  
Gas Compression ◽  
Smooth Disk

The theory underlying a novel method of gas compression driven by shear flow for next generation turbo-machinery is presented. The concept is based on the conversion of shaft power into hydrodynamic pressure and fluid flow that occur in the shear flow between a smooth rotating disk and a compliant surface counterface. This also holds for the inverse process, where gas expansion through the gap between the compliant surface and a shaft-mounted disk converts gas pressure into rotating power and torque. This is a logical evolutionary step that leverages the proven functionality of self-actuated fluid film compliant foil bearings and seals which operate in the hydrodynamic regime. Thus, as in these devices, the process of compression induced by shear flow is dominated by the balance between pressure and viscous forces which are in turn enhanced and controlled by tribological effects arising between the fluid film and the geometry of the counterface compliant surface. A model based on the compressible Reynolds equation coupled to the thin-plate theory formulation for compliant foil deflection is presented and parametrically solved to predict pressure, flow rate, and shear losses. The smooth disk and four-pad (sectored) compliant counterface effective size (7.6 mm < r < 14.1 mm), disk operating speed (50,000 to 360,000 rpm), nominal initial gap (0.03 mm < h0 < 0.635 mm), and overall operating conditions chosen for the parametric study correspond to those envisioned for eventual practical integration of miniaturized external combustion bladeless gas turbine engines and turbocompressors. Theoretical performance curves reporting flow versus pressure as well as compression power requirements versus speed were obtained. The predictions of the analysis are compared to results obtained experimentally on a proof of concept engine and presented in a companion paper. The simplicity of the bladeless geometry makes it amenable to deployment in multistage configurations, so that in conjunction with its foil bearing predecessors, this novel technology will result in low cost, ultra-high speed, high specific power and power density, high efficiency, oil-free and maintenance-free engines — attractive for many practical applications, ranging from military micro-UAV propulsion and portable power systems, to domestic combined heat and power turboalternators, and even micro-compressors for portable medical devices. As a point of reference, it is anticipated that a 10-stage bladeless compressor based on a compression stage as described herein would have a size comparable to that of a 355 mL soda can delivering a flow of 1 kg/min of compressed air.

Introduction and Performance Prediction of a Nutating-Disk Engine

1999 ◽  
Author(s):  
T. Korakianitis ◽  
L. Meyer ◽  
M. Boruta ◽  
H. E. McCormick
Keyword(s):  
Combustion Chamber ◽  
Gas Turbine ◽  
Gas Turbines ◽  
Combustion Engine ◽  
Thermodynamic Cycle ◽  
Rotating Disk ◽  
Simple Cycle ◽  
Specific Power ◽  
Engine Operation ◽  
Stroke Engine

A new type of internal combustion engine and its thermodynamic cycle are introduced. The core of the engine is a nutating non-rotating disk, with the center of its hub mounted in the middle of a Z-shaped shaft. The two ends of the shaft rotate, while the disk nutates. The motion of the disk circumference prescribes a portion of a sphere. A portion of the area of the disk is used for intake and compression, a portion is used to seal against a center casing, and the remaining portion is used for expansion and exhaust. The compressed air is admitted to an external accumulator, and then into an external combustion chamber before it is admitted to the power side of the disk. The accumulator and combustion chamber are kept at constant pressures. The engine has a few analogies with piston-engine operation, but like a gas turbine it has dedicated spaces and devices for compression, burning and expansion. The thermal efficiency is similar to that of comparably-sized simple-cycle gas turbines and piston engines. For the same engine volume and weight, this engine produces less specific power than a simple-cycle gas turbine, but approximately twice the power of a two-stroke engine and four times the power of a four-stroke engine. The engine has advantages in the 10 kW to 200 kW power range. This paper introduces the geometry and thermodynamic model for the engine, presents typical performance curves, and discusses the relative advantages of this engine over its competitors.

scholarly journals Gas Turbine Health State Determination: Methodology Approach and Field Application

2012 ◽  
Vol 2012 ◽  
pp. 1-14 ◽  
Author(s):  
Michele Pinelli ◽  
Pier Ruggero Spina ◽  
Mauro Venturini
Keyword(s):  
Gas Turbine ◽  
Gas Turbines ◽  
Field Measurements ◽  
Field Application ◽  
Diagnostic Process ◽  
Health State ◽  
Gas Compression ◽  
State Determination ◽  
Measurement Validation ◽  
Machine Health

A reduction of gas turbine maintenance costs, together with the increase in machine availability and the reduction of management costs, is usually expected when gas turbine preventive maintenance is performed in parallel to on-condition maintenance. However, on-condition maintenance requires up-to-date knowledge of the machine health state. The gas turbine health state can be determined by means of Gas Path Analysis (GPA) techniques, which allow the calculation of machine health state indices, starting from measurements taken on the machine. Since the GPA technique makes use of field measurements, the reliability of the diagnostic process also depends on measurement reliability. In this paper, a comprehensive approach for both the measurement validation and health state determination of gas turbines is discussed, and its application to a 5 MW gas turbine working in a natural gas compression plant is presented.

Tracings of Behavior of Myoblasts Cultured Under Couette Type of Shear Flow Between Parallel Disks

2021 ◽  
Author(s):  
Shigehiro Hashimoto ◽  
Hiroki Yonezawa
Keyword(s):  
Shear Stress ◽  
Shear Flow ◽  
Rotating Disk ◽  
Time Lapse ◽  
Mechanical Stimuli ◽  
Parallel Disks ◽  
Before And After ◽  
A Cell

Abstract A cell deforms and migrates on the scaffold under mechanical stimuli in vivo. In this study, a cell with division during shear stress stimulation has been observed in vitro. Before and after division, both migration and deformation of each cell were analyzed. To make a Couette-type shear flow, the medium was sandwiched between parallel disks (the lower stationary culture-disc and the upper rotating disk) with a constant gap. The wall shear stress (1.5 Pa &lt; τ &lt; 2 Pa) on the surface of the lower culture plate was controlled by the rotational speed of the upper disc. Myoblasts (C2C12: mouse myoblast cell line) were used in the test. After cultivation without flow for 24 hours for adhesion of the cells to the lower disk, constant τ was applied to the cells in the incubator for 7 days. The behavior of each cell during shear was tracked by time-lapse images observed by an inverted phase contrast microscope placed in the incubator. Experimental results show that each cell tends to divide after higher activities: deformation and migration. The tendency is remarkable at the shear stress of 1.5 Pa.

Physical Interpretation of Flow and Heat Transfer in Preswirl Systems

2006 ◽  
Vol 129 (3) ◽  
pp. 769-777 ◽  
Author(s):  
Paul Lewis ◽  
Mike Wilson ◽  
Gary Lock ◽  
J. Michael Owen
Keyword(s):  
Heat Transfer ◽  
Reynolds Number ◽  
Nusselt Number ◽  
Turbulent Flow ◽  
Gas Turbines ◽  
Flow Parameter ◽  
Rotating Disk ◽  
Turbine Rotor ◽  
Scaled Model ◽  
Flow Rates

This paper compares heat transfer measurements from a preswirl rotor–stator experiment with three-dimensional (3D) steady-state results from a commercial computational fluid dynamics (CFD) code. The measured distribution of Nusselt number on the rotor surface was obtained from a scaled model of a gas turbine rotor–stator system, where the flow structure is representative of that found in an engine. Computations were carried out using a coupled multigrid Reynolds-averaged Navier-Stokes (RANS) solver with a high Reynolds number k-ε∕k-ω turbulence model. Previous work has identified three parameters governing heat transfer: rotational Reynolds number (Reϕ), preswirl ratio (βp), and the turbulent flow parameter (λT). For this study rotational Reynolds numbers are in the range 0.8×106<Reϕ<1.2×106. The turbulent flow parameter and preswirl ratios varied between 0.12<λT<0.38 and 0.5<βp<1.5, which are comparable to values that occur in industrial gas turbines. Two performance parameters have been calculated: the adiabatic effectiveness for the system, Θb,ad, and the discharge coefficient for the receiver holes, CD. The computations show that, although Θb,ad increases monotonically as βp increases, there is a critical value of βp at which CD is a maximum. At high coolant flow rates, computations have predicted peaks in heat transfer at the radius of the preswirl nozzles. These were discovered during earlier experiments and are associated with the impingement of the preswirl flow on the rotor disk. At lower flow rates, the heat transfer is controlled by boundary-layer effects. The Nusselt number on the rotating disk increases as either Reϕ or λT increases, and is axisymmetric except in the region of the receiver holes, where significant two-dimensional variations are observed. The computed velocity field is used to explain the heat transfer distributions observed in the experiments. The regions of peak heat transfer around the receiver holes are a consequence of the route taken by the flow. Two routes have been identified: “direct,” whereby flow forms a stream tube between the inlet and outlet; and “indirect,” whereby flow mixes with the rotating core of fluid.

Arrangement and Optimisation Turbocompressors in an Off-Shore Natural Gas Extraction Station

2005 ◽  
Author(s):  
M. Pinelli ◽  
A. Mazzi ◽  
G. Russo
Keyword(s):  
Centrifugal Compressor ◽  
Gas Turbines ◽  
Optimization Procedure ◽  
Thermodynamic Cycle ◽  
Actual Operating ◽  
Gas Compression ◽  
Consequent Reduction ◽  
Suitable Arrangement ◽  
High Production ◽  
Definition Of

In this paper, a methodology for the optimization of a single off-shore gas compression station is developed. The station is composed of three gas turbines, each one driving a centrifugal compressor. The study concerns the feasibility of the most suitable arrangement to face the depletion of wells and the consequent reduction of the head top pressure. Once the arrangement is chosen, an optimization procedure is developed and carried out. The procedure, which is aimed at obtaining either high production rates or good station efficiency, is based on knowledge of the centrifugal compressor characteristics and on the availability of gas turbine thermodynamic cycle program, the latter allowing the definition of the machine actual operating state.

Analysis of the Thermodynamic Performance of Kalina Cycle System 11 (KCS11) for Geothermal Power Plant: Comparison With Kawerau ORMAT Binary Plant

2009 ◽  
Author(s):  
Xinli Lu ◽  
Arnold Watson ◽  
Joe Deans
Keyword(s):  
Power Generation ◽  
Power Plant ◽  
Heat Source ◽  
Gas Turbines ◽  
Effective Means ◽  
Specific Power ◽  
Kalina Cycle ◽  
Geothermal Power Plant ◽  
Thermodynamic Performance ◽  
Geothermal Power

Since the first geothermal power plant was built at Larderello (Italy) in 1904, many attempts have been made to improve conversion efficiency. Among innovative technologies, using the Kalina cycle is considered as one of the most effective means of enhancing the thermodynamic performance for both high and low temperature heat source systems. Although initially used as the bottoming cycle of gas turbines and diesel engines, in the late 1980s the Kalina cycle was found to be attractive for geothermal power generation [1, 2, 3]. Different versions (KSC11, KSC12 and KSC13) were designated. Comparison between Kalina cycle and other power cycles can be found in later studies [4, 5, 6]. Here we examine KSC11, because it is specifically designed for geothermal power generation, with lower capital cost [3]. We compare this design with the existing Kawerau ORMAT binary plant in New Zealand. In addition, parametric sensitivity analysis of KCS11 has been carried out for the specific power output and net thermal efficiency by changing the temperatures of both heat source and heat sink for a given ammonia-water composition.

Optimisation of CO Turndown for an Axially Staged Gas Turbine Combustor

2020 ◽  
Author(s):  
Jacob E. Rivera ◽  
Robert L. Gordon ◽  
Mohsen Talei ◽  
Gilles Bourque
Keyword(s):  
Residence Time ◽  
Parametric Study ◽  
Gas Turbines ◽  
Flow Reactor ◽  
Operating Conditions ◽  
Independent Effect ◽  
Inlet Temperature ◽  
Operating Characteristics ◽  
Two Stage ◽  
The Impact

Abstract This paper reports on an optimisation study of the CO turndown behaviour of an axially staged combustor, in the context of industrial gas turbines (GT). The aim of this work is to assess the optimally achievable CO turndown behaviour limit given system and operating characteristics, without considering flow-induced behaviours such as mixing quality and flame spatial characteristics. To that end, chemical reactor network modelling is used to investigate the impact of various system and operating conditions on the exhaust CO emissions of each combustion stage, as well as at the combustor exit. Different combustor residence time combinations are explored to determine their contribution to the exhaust CO emissions. The two-stage combustor modelled in this study consists of a primary (Py) and a secondary (Sy) combustion stage, followed by a discharge nozzle (DN), which distributes the exhaust to the turbines. The Py is modelled using a freely propagating flame (FPF), with the exhaust gas extracted downstream of the flame front at a specific location corresponding to a specified residence time (tr). These exhaust gases are then mixed and combusted with fresh gases in the Sy, modelled by a perfectly stirred reactor (PSR) operating within a set tr. These combined gases then flow into the DN, which is modelled by a plug flow reactor (PFR) that cools the gas to varying combustor exit temperatures within a constrained tr. Together, these form a simplified CRN model of a two-stage, dry-low emissions (DLE) combustion system. Using this CRN model, the impact of the tr distribution between the Py, Sy and DN is explored. A parametric study is conducted to determine how inlet pressure (Pin), inlet temperature (Tin), equivalence ratio (ϕ) and Py-Sy fuel split (FS), individually impact indicative CO turndown behaviour. Their coupling throughout engine load is then investigated using a model combustor, and its effect on CO turndown is explored. Thus, this aims to deduce the fundamental, chemically-driven parameters considered to be most important for identifying the optimal CO turndown of GT combustors. In this work, a parametric study and a model combustor study are presented. The parametric study consists of changing a single parameter at a time, to observe the independent effect of this change and determine its contribution to CO turndown behaviour. The model combustor study uses the same CRN, and varies the parameters simultaneously to mimic their change as an engine moves through its steady-state power curve. The latter study thus elucidates the difference in CO turndown behaviour when all operating conditions are coupled, as they are in practical engines. The results of this study aim to demonstrate the parameters that are key for optimising and improving CO turndown.

The Effect of Alternative Turbine Cooling Schemes on the Performance of Utility Gas Turbine Powerplants

1982 ◽  
Author(s):  
Arthur Cohn ◽  
Mark Waters
Keyword(s):  
High Temperature ◽  
Gas Turbines ◽  
Power Plants ◽  
Heat Rate ◽  
Combined Cycle ◽  
Specific Power ◽  
Cooling Effectiveness ◽  
Turbine Cooling ◽  
The Impact ◽  
Systems Studies

It is important that the requirements and cycle penalties related to the cooling of high temperature turbines be thoroughly understood and accurately factored into cycle analyses and power plant systems studies. Various methods used for the cooling of high temperature gas turbines are considered and cooling effectiveness curves established for each. These methods include convection, film and transpiration cooling using compressor bleed and/or discharge air. In addition, the effects of chilling the compressor discharge cooling gas are considered. Performance is developed to demonstrate the impact of the turbine cooling schemes on the heat rate and specific power of Combined–Cycle power plants.

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