Compressible Flowfield Characteristics of Butterfly Valves

1989 ◽  
Vol 111 (4) ◽  
pp. 400-407 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Flow Separation ◽  
Pressure Ratio ◽  
Disk Surface ◽  
Surface Flow ◽  
Operating Conditions ◽  
Local Geometry ◽  
Operating Pressure ◽  
Butterfly Valve ◽  
Pressure Distributions ◽  
Flow Separation And Reattachment

The results of an experimental investigation into the flowfield characteristics of butterfly valves under compressible flow operating conditions are reported. The experimental results include Schlieren and surface flow visualizations and flowfield static pressure distributions. Two valve disk shapes have been studied in a planar, two-dimensional test section: a generic biconvex circular arc profile and the midplane cross-section of a prototype butterfly valve. The valve disk angle and operating pressure ratio have also been varied in these experiments. The results demonstrate that under certain conditions of operation the butterfly valve flowfield can be extremely complex with oblique shock waves, expansion fans, and regions of flow separation and reattachment. In addition, the sensitivity of the valve disk surface pressure distributions to the local geometry near the leading and trailing edges and the relation of the aerodynamic torque to flow separation and reattachment on the disk are shown.

Numerical and Experimental Investigation of Pulsating Flow Effect on a Nozzled and Nozzleless Mixed Flow Turbine for an Automotive Turbocharger

2014 ◽  
Author(s):  
M. H. Padzillah ◽  
M. Yang ◽  
W. Zhuge ◽  
R. F. Martinez-Botas
Keyword(s):  
Pressure Ratio ◽  
Turbine Blades ◽  
Computational Cost ◽  
Operating Conditions ◽  
Pulsating Flow ◽  
Angle Distribution ◽  
Operating Pressure ◽  
Flow Conditions ◽  
Flow Angle ◽  
Turbine Speed

To achieve better flow guidance into the turbine blades, nozzle vanes were added as an integral part of the stator design. However, the full investigation that directly addresses the comparison between the two turbine arrangements under pulsating flow conditions is still not available in literature. This work represents the first attempt to observe differences, particularly in the circumferential flow angle distribution between both volute arrangements under steady and pulsating flow operating conditions. Experimentally validated Computational Fluid Dynamics (CFD) simulations have been conducted in order to achieve this aim. As the experimental data within the Turbocharger Group at Imperial College are extensive, the simulation procedures are optimized to achieve the best compromise between the computational cost and prediction accuracy. A single operating pressure ratio is selected for the steady and pulsating environment in order to provide consistent comparison for both volute arrangements. The simulation results presented in this work are conducted at the turbine speed of 48000rpm and 60Hz flow frequency for the pulsating flow simulations. The results indicated that there are significant differences in the flow angle behavior for both volutes regardless of the flow conditions (steady or unsteady). It is also found that the differences in flow angle distribution between increasing and decreasing pressure instances during pulsating flow operation is more prominent in the nozzleless volute than its nozzled counterpart.

Numerical Investigation of Negative Flow Characteristics in a Centrifugal Compressor with Vaned Diffuser and Internal Volute

2021 ◽  
Author(s):  
Bing Qiao ◽  
Yaping Ju ◽  
Chuhua Zhang
Keyword(s):  
Centrifugal Compressor ◽  
Flow Separation ◽  
Incidence Angle ◽  
Pressure Ratio ◽  
Surface Flow ◽  
Flow Dynamics ◽  
Suction Surface ◽  
Vaned Diffuser ◽  
Flow Rates ◽  
Compressor Aerodynamics

Abstract Negative flow from the outlet through the volute, diffuser, and impeller to the inlet of the centrifugal compressor can occur continuously as a result of system accidents. A physical comprehension of negative flow dynamics is crucial in evaluating the compressor characteristics under abnormal working conditions, and is also important in exploring the compressor aerodynamics over the entire flow range. However, limited research on the negative flow dynamics in centrifugal compressors, particularly with the consideration of vaned diffusers and volutes, can be found. This study aims to determine the compressor characteristics, including the negative flow rates of a centrifugal compressor, and to clarify the negative flow mechanism under the interaction of the volute, diffuser, and impeller. The last stage of a four-stage centrifugal compressor, including an internal volute, a vaned diffuser, and a closed impeller was simulated under both positive and negative flow conditions using a computational fluid dynamics (CFD) model. The results show that the pressure ratio-negative flow characteristic is almost matched with a parabolic curve. At negative flow rates, the backflow generated on the hub and shroud sides in the impeller expands upstream and causes flow separation in the diffuser. The negative flow enters the impeller at a large incidence angle and results in jet wall impingement on the pressure surface, flow spillage over the trailing edge, and flow separation near the suction surface. The impeller partially acts as a turbine impeller and performs negative work on the fluid. This work is of scientific significance to enrich the compressor aerodynamics in accident scenarios and of engineering value to improve the advanced design of compressor protection systems.

Aerodynamic Torque Characteristics of Butterfly Valves in Compressible Flow

1989 ◽  
Vol 111 (4) ◽  
pp. 392-399 ◽  
Author(s):  
M. J. Morris ◽  
J. C. Dutton
Keyword(s):  
Compressible Flow ◽  
Pressure Ratio ◽  
Three Dimensional ◽  
Operating Pressure ◽  
Pressure Gradients ◽  
Flow Conditions ◽  
Trailing Edges ◽  
Operating Points ◽  
Aerodynamic Torque ◽  
Flow Separation And Reattachment

The results of an experimental investigation of the aerodynamic torque characteristics of butterfly valves under compressible flow conditions are reported. Both three-dimensional prototype valves and two-dimensional planar models have been studied at choked and unchoked operating points. Other parameters investigated include the operating pressure ratio across the valve, the valve disk angle, and the disk shape. The results demonstrate the importance of flow separation and reattachment phenomena on the valve aerodynamic torque characteristics, the importance of disk shape at intermediate angles, and the sensitivity of the torque to the valve disk geometry near the leading and trailing edges where extreme pressure gradients can occur.

Thermodynamic design of a reciprocating Joule cycle engine

2003 ◽  
Vol 217 (3) ◽  
pp. 239-246 ◽  
Author(s):  
M. A. Bell ◽  
T Partridge
Keyword(s):  
Thermal Efficiency ◽  
Pressure Ratio ◽  
Volume Ratio ◽  
Thermodynamic Cycle ◽  
Operating Conditions ◽  
Specific Work ◽  
Operating Pressure ◽  
Regenerative Heat ◽  
Pressure Drops ◽  
Swept Volume

This paper describes a first-order model of a Reciprocating Joule Cycle (RJC) engine, which is then used to investigate its thermodynamic design with a view to establishing its optimum performance for a given set of operating conditions. The RJC engine is essentially the reciprocating counterpart of the gas turbine. Its performance is determined by the characteristics of a reciprocating, as opposed to a rotodynamic, compressor and expander. The thermodynamic cycle investigated incorporates regenerative heat exchange. An air standard model modified to include the effects of friction, combustion, clearance volumes, leakage and pressure drops, shows that the performance of the RJC engine is strongly dependent on its operating pressure ratio and dependent to a much lesser extent on its expander to compressor swept volume ratio. It is shown that a thermal efficiency approaching 50 per cent might be achievable under realistic conditions. Using a maximum operating temperature of 1300 K, optimum thermal efficiency with a high specific work output occurs when its nominal operating pressure ratio is in the range 6 to 8, and its expander to compressor swept volume ratio is in the range 2 to 3. The RJC engine is proposed as a suitable prime mover for micro-CHP systems, small stand-alone power units, or hybrid vehicles.

Effect of operating conditions on rejection of anionic pollutants in the water environment by nanofiltration especially in very low pressure range

1996 ◽  
Vol 34 (9) ◽  
pp. 149-156 ◽  
Author(s):  
C. Ratanatamskul ◽  
K. Yamamoto ◽  
T. Urase ◽  
S. Ohgaki
Keyword(s):  
Water Environment ◽  
Chloride Ions ◽  
Operating Conditions ◽  
Transmembrane Pressure ◽  
Operating Pressure ◽  
Nanofiltration Membranes ◽  
Single Solution ◽  
Crossflow Velocity ◽  
Membrane Type ◽  
New Generation

The recent development of new generation LPRO or nanofiltration membranes have received attraction for application in the field of wastewater and water treatment through an increasingly stringent regulation for drinking purpose and water reclamation. In this research, the application on treatment of anionic pollutants (nitrate, nitrite, phosphate, sulfate and chloride ions) have been investigated as functions of transmembrane pressure, crossflow velocity and temperature under very much lower pressure operation range (0.49 to 0.03 MPa) than any other previous research used to do. Negative rejection was also observed under very much low range of operating pressure in the case of membrane type NTR-7250. Moreover, the extended Nernst-Planck model was used for analysis of the experimental data of the rejection of nitrate, nitrite and chloride ions in single solution by considering effective charged density of the membranes.

scholarly journals Large Eddy Simulations of Strongly Non-Ideal Compressible Flows through a Transonic Cascade

Energies ◽  
2021 ◽  
Vol 14 (3) ◽  
pp. 772
Author(s):  
Jean-Christophe Hoarau ◽  
Paola Cinnella ◽  
Xavier Gloerfelt
Keyword(s):  
Compressible Flows ◽  
Flow Behavior ◽  
Pressure Ratio ◽  
Organic Rankine Cycle ◽  
Ideal Gas ◽  
Operating Conditions ◽  
Large Eddy Simulations ◽  
Working Fluid ◽  
Viscous Effects ◽  
Large Eddy

Transonic flows of a molecularly complex organic fluid through a stator cascade were investigated by means of large eddy simulations (LESs). The selected configuration was considered as representative of the high-pressure stages of high-temperature Organic Rankine Cycle (ORC) axial turbines, which may exhibit significant non-ideal gas effects. A heavy fluorocarbon, perhydrophenanthrene (PP11), was selected as the working fluid to exacerbate deviations from the ideal flow behavior. The LESs were carried out at various operating conditions (pressure ratio and total conditions at inlet), and their influence on compressibility and viscous effects is discussed. The complex thermodynamic behavior of the fluid generates highly non-ideal shock systems at the blade trailing edge. These are shown to undergo complex interactions with the transitional viscous boundary layers and wakes, with an impact on the loss mechanisms and predicted loss coefficients compared to lower-fidelity models relying on the Reynolds-averaged Navier–Stokes (RANS) equations.

Improvement of the Static and Dynamic Characteristics of Magnetic Head Sliders by Optimum Design

1999 ◽  
Vol 122 (1) ◽  
pp. 280-287 ◽  
Author(s):  
Hiromu Hashimoto ◽  
Yasuhisa Hattori
Keyword(s):  
Objective Function ◽  
Optimum Design ◽  
Amplitude Ratio ◽  
Optimization Technique ◽  
Hard Disk Drives ◽  
Maximum Amplitude ◽  
Disk Surface ◽  
Operating Conditions ◽  
Magnetic Head ◽  
Design Variables

The aim of this paper is to develop a general methodology for the optimum design of magnetic head sliders in improving the spacing characteristics between a slider and disk surface under static and dynamic operating conditions of hard disk drives and to present an application of the methodology to the IBM 3380-type slider design. To generate the optimal design variables, the objective function is defined as the weighted sum of the minimum spacing, the maximum difference in the spacing due to variation of the radial location of the head, and the maximum amplitude ratio of the slider motion. Slider rail width, taper length, taper angle, suspension position, and preload are selected as the design variables. Before the optimization of the head, the effects of these five design variables on the objective function are examined by a parametric study, and then the optimum design variables are determined by applying the hybrid optimization technique, combining the direct search method and successive quadratic programming. From the obtained results, the effectiveness of optimum design on the spacing characteristics of magnetic heads is clarified. [S0742-4787(00)03701-2]

Designing CO2 Transmission Pipelines Without Crack Arrestors

2010 ◽  
Author(s):  
Graeme G. King ◽  
Satish Kumar
Keyword(s):  
Wall Thickness ◽  
Carbon Capture ◽  
Power Plants ◽  
Oil And Gas ◽  
Cost Optimization ◽  
Operating Conditions ◽  
Operating Pressure ◽  
Design Work ◽  
Industrial Facilities ◽  
Pipeline Network

Masdar is developing several carbon capture projects from power plants, smelters, steel works, industrial facilities and oil and gas processing plants in Abu Dhabi in a phased series of projects. Captured CO2 will be transported in a new national CO2 pipeline network with a nominal capacity of 20×106 T/y to oil reservoirs where it will be injected for reservoir management and sequestration. Design of the pipeline network considered three primary factors in the selection of wall thickness and toughness, (a) steady and transient operating conditions, (b) prevention of longitudinal ductile fractures and (c) optimization of total project owning and operating costs. The paper explains how the three factors affect wall thickness and toughness. It sets out code requirements that must be satisfied when choosing wall thickness and gives details of how to calculate toughness to prevent propagation of long ductile fracture in CO2 pipelines. It then uses cost optimization to resolve contention between the different requirements and arrive at a safe and economical pipeline design. The design work selected a design pressure of 24.5 MPa, well above the critical point for CO2 and much higher than is normally seen in conventional oil and gas pipelines. Despite its high operating pressure, the proposed network will be one of the safest pipeline systems in the world today.

Morphological Adaptation for Speed Control of Pipeline Inspection Gauges MC-PIG

2021 ◽  
Author(s):  
Sujet Phodapol ◽  
Tachadol Suthisomboon ◽  
Pong Kosanunt ◽  
Ravipas Vongasemjit ◽  
Petch Janbanjong ◽  
...  
Keyword(s):  
Fluid Velocity ◽  
Operating Conditions ◽  
Pi Control ◽  
Operating Pressure ◽  
Acceptable Error ◽  
Valve Unit ◽  
Pipeline Inspection ◽  
Flow Adjustment ◽  
Valve Angle ◽  
Moving Speed

Abstract Passive and active hybrid pipeline inspection gauges (PIGs) have been used for in-pipe inspection. While a passive PIG cannot control its speed, the hybrid version can achieve this by using an integrated valve specifically designed and embedded in the PIG. This study proposes a generic new method for speed adaptation in PIGs (called MC-PIG) by introducing a generic, modular, controllable, external valve unit add-on for attaching to existing conventional (passive) PIGs with minimal change. The MC-PIG method is based on the principle of morphological computation with closed-loop control. It is achieved by regulating/computing the PIG's morphology (i.e., a modular rotary valve unit add-on) to control bypass flow. Adjustment of the valve angle can affect the flow rate passing through the PIG, resulting in speed regulation ability. We use numerical simulation with computational fluid dynamics (CFD) to investigate and analyze the speed of a simulated PIG with the valve unit adjusted by proportional-integral (PI) control under various in-pipe pressure conditions. Our simulation experiments are performed under different operating conditions in three pipe sizes (16″, 18″, and 22″ in diameter) to manifest the speed adaptation of the PIG with the modular valve unit add-on and PI control. Our results show that the PIG can effectively perform real-time adaptation (i.e., adjusting its valve angle) to maintain the desired speed. The valve design can be adjusted from 5 degrees (closed valve, resulting in high moving speed) to a maximum of 45 degrees (fully open valve, resulting in low moving speed). The speed of the PIG can be regulated from 0.59 m/s to 3.88 m/s in a 16″ pipe at 4.38 m/s (in-pipe fluid velocity), 2500 kPa (operating pressure), and 62 °C (operating temperature). Finally, the MC-PIG method is validated using a 3D-printed prototype in a 6″ pipe. Through the investigation, we observed that two factors influence speed adaptation; the pressure drop coefficient and friction of the PIG and pipeline. In conclusion, the results from the simulation and prototype show close characteristics with an acceptable error.

Numerical Analysis of Non-Radial Blading in a Low Speed and Low Pressure Turbine for Electric Turbocompounding Applications

2021 ◽  
Author(s):  
Eva Alvarez-Regueiro ◽  
Esperanza Barrera-Medrano ◽  
Ricardo Martinez-Botas ◽  
Srithar Rajoo
Keyword(s):  
Numerical Analysis ◽  
Numerical Simulations ◽  
Thermal Stresses ◽  
Waste Heat ◽  
Pressure Ratio ◽  
Low Pressure ◽  
Turbine Rotor ◽  
Operating Conditions ◽  
Blade Angle ◽  
Low Speed

Abstract This paper presents a CFD-based numerical analysis on the potential benefits of non-radial blading turbine for low speed-low pressure applications. Electric turbocompounding is a waste heat recovery technology consisting of a turbine coupled to a generator that transforms the energy left over in the engine exhaust gases, which is typically found at low pressure, into electricity. Turbines designed to operate at low specific speed are ideal for these applications since the peak efficiency occurs at lower pressure ratios than conventional high speed turbines. The baseline design consisted of a vaneless radial fibre turbine, operating at 1.2 pressure ratio and 28,000rpm. Experimental low temperature tests were carried out with the baseline radial blading turbine at nominal, lower and higher pressure ratio operating conditions to validate numerical simulations. The baseline turbine incidence angle effect was studied and positive inlet blade angle impact was assessed in the current paper. Four different turbine rotor designs of 20, 30, 40 and 50° of positive inlet blade angle are presented, with the aim to reduce the losses associated to positive incidence, specially at midspan. The volute domain was included in all CFD calculations to take into account the volute-rotor interactions. The results obtained from numerical simulations of the modified designs were compared with those from the baseline turbine rotor at design and off-design conditions. Total-to-static efficiency improved in all the non-radial blading designs at all operating points considered, by maximum of 1.5% at design conditions and 5% at off-design conditions, particularly at low pressure ratio. As non-radial fibre blading may be susceptible to high centrifugal and thermal stresses, a structural analysis was performed to assess the feasibility of each design. Most of non-radial blading designs showed acceptable levels of stress and deformation.

Sign in / Sign up

Export Citation Format

Share Document