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Projects: Projects for Investigator
Reference Number	NIA_NGGT0035
Title	Investigation of flow physics in gas pipe network
Status	Completed
Energy Categories	Fossil Fuels: Oil Gas and Coal(Oil and Gas, Refining, transport and storage of oil and gas) 100%;
Research Types	Applied Research and Development 100%
Science and Technology Fields	PHYSICAL SCIENCES AND MATHEMATICS (Physics) 50%; ENGINEERING AND TECHNOLOGY (Mechanical, Aeronautical and Manufacturing Engineering) 50%;
UKERC Cross Cutting Characterisation	Not Cross-cutting 100%
Principal Investigator	Project Contact No email address given National Grid Gas Transmission
Award Type	Network Innovation Allowance
Funding Source	Ofgem
Start Date	01 October 2014
End Date	01 May 2018
Duration	43 months
Total Grant Value	£169,000
Industrial Sectors	Technical Consultancy
Region	London
Programme	Network Innovation Allowance
Investigators	Principal Investigator	Project Contact , National Grid Gas Transmission (100.000%)
Web Site	http://www.smarternetworks.org/project/NIA_NGGT0035
Objectives	This project aims to create comprehensive fast transient models (using computational fluid dynamics (CFD) methods) of National Transmission System (NTS) components to enable a fuller understanding of the expected impact of quick flow changes on the system. This will also facilitate validation of the default 50 MW/minute ramp rate. Publication of a technical paper / thesis on the work with discussions on the findings, recommendations and suggestions for further work. Production of detailed models of local NTS components. Proposal of a new default ramp rate or provision of analysis data to justify the existing value. Integration of existing network modeling software with CFD models.
Abstract	Drastic changes in flow rates can have adverse impact on pipes and associated network equipment such as Compressors and Valves. This can be attributed to manifestation of fast transient effects such as flow (hence pressure) spikes, flow/pressure oscillations (pressure waves) and high velocity. Normally the largest flow changes occur during start-up and shutdown. As such when new Customers wish to connect to the NTS, they are assigned, default, 50 MW/minute as the maximum rate at which they can increase or decrease their flow rate, i.e. the default "Ramp Rate". Where a Customer wishes to have a Ramp Rate higher than the default value, a feasibility study, that includes Fast Transient Analysis, is carried out to investigate whether a requested Ramp Rate would create a large disturbance in the local pipe flows which could have undesirable effect on the local and/or neighbouring pipework and plant equipment. National Grid has identified the need to decrease requirements for ramp rate studies using an adjusted default value, along with a reduction in the time currently required to carry out a Fast Transient Analysis, while maintaining, or even improving, the quality of the output forms. A need has also been intensified to increase knowledge and appreciation of the impact of fast transient on the local transmission system; define and standardise fast transient analysis outputs; and to extend/compliment the capability of existing network modelling tools. This project will look at comprehensive fast transient models using computational fluid dynamics (CFD) methods to allow a fuller understanding of the expected impact of quick flow changes on the system. This work will allow for validation of default 50 MW/minute ramp rate. In this collaborative project between National Grid and the University of Manchester, a recently developed technique known as Embedded Large Eddy Simulation (ELES), coupled with the Large Eddy Simulation (LES), will be applied in conjunction with the Reynolds-averaged Navier-Stokes (RANS) equation model. It is anticipated that this approach will enable a breakthrough in the Reynolds-number range accessible with high-accuracy flow, noise and vibration simulations. Deliverable 1: Validation of Method Development and application of the ELES approach to examine in detail the impact of an unsteady flow (i.e. surge) through precise representation of local pipework and specific equipment. Benchmarking exercise with existing results, for external CFD reports or internal network modelling. Performing a sensitivity analysis, by studying a range of flow parameters around those typically assumed, in order to quantifiably assess the sensitivity and likely bounds of error. Deliverable 2: Reassessment of the 50MW/min trigger point Perform simulations with ELES to enable a high level of detail to be obtained about the flow physics during a surge situation for the first time. Scenario analysis to examine in detail the flow associated with a range of different ramp-up rates, in order to investigate the hypothesis that the current trigger is too conservative. Detailed study will be undertaken of regions of unsteady separated flow in order to link to potential modes of structural vibration. Provide a framework for the calibration of the reduced order modelling employed in network-scale analysis. In this way the accuracy of 1-D or 2-D network models can be improved for specific junctions, configurations. Deliverable 3:Integration of tool into NG workflow Developed ELES method further, with potential to automating the workflow further. Identify trigger points arising from low order modelling that indicate the need for more detailed simulation. Generation of the mesh, the definition of the limits of the embedded region, the initialization of the unsteady flow and the time-averaging will all be automated, in order to establish a reliable, repeatable prediction tool. Deliverable 4: Knowledge transfer The software used will be open-source to enable knowledge transfer within National Grid for future scenarios to be run in-house once the research is complete, and to provide learnings to other licensees.Note : Project Documents may be available via the ENA Smarter Networks Portal using the Website link above
Publications	(none)
Final Report	(none)
Added to Database	21/08/18