Imran Qureshi | University of Oxford (original) (raw)
Papers by Imran Qureshi
International Journal of Precision Engineering and Manufacturing-Green Technology, 2019
Titanium alloys are generally known as difficult-to-machine materials because of their low machin... more Titanium alloys are generally known as difficult-to-machine materials because of their low machinability ratings. Their usage is favored for demanding sectors because of their high strength to weight ratio, high corrosion resistance and ability to operate at elevated temperatures. Machining of titanium alloys results in higher environmental burden, because they require high energy and generous amount of cutting fluids during machining. It is a well-known fact that most of the cutting fluids are toxic and non-biodegradable in nature and their disposal is costly. Therefore, researchers in metal cutting are keen to explore the potential of minimum quantity lubrication (MQL) and minimum quantity cooling lubrication (MQCL) based cooling techniques as an alternate to conventional flood cooling. When MQL and MQCL techniques are used by employing biodegradable vegetable based oils then there is an encouraging potential of replacing the non-biodegradable cutting fluids. This study documents the recent experimental and numerical advances achieved in the MQL and MQCL assisted techniques for machining titanium alloys. The study also highlights the current challenges in this area and recommends future work to address these challenges.
Flow Measurement and Instrumentation, 2019
The range of flow angles that can be measured accurately using multi-hole probes is restricted du... more The range of flow angles that can be measured accurately using multi-hole probes is restricted due to limitations, such as singularity, in the calibration techniques used. Several modified techniques have been proposed for five and seven-hole probes to extend their usable range of operation. However fewer techniques are available in the literature for four-hole probe, which has an advantage over its counterparts because of its smaller size. This research fills the gap by reviewing the techniques implemented successfully on either five or seven-hole probes operating in non-nulling mode to extend their calibration maps and then adapting those techniques for four-hole probes. Three techniques, in addition to the traditional technique, are adapted for a four-hole probe by suitable modification. The adapted techniques have been implemented on the calibration data set of actual flow angles and raw pressures from a four-hole probe. The results from the validation of all three techniques are compared with the results from traditional technique to evaluate the resulting extension in the calibration maps. Overall, all methods showed an extension in the region of usable calibration map compared to the traditional technique. However, the results showed an advantage for the new zonal method technique, which offered a significant extension in the calibration map of a four-hole probe. It is the first time that such a consolidated effort has been done to extend the calibration map of a four-hole probe for measuring high flow angles.
Sustainable Energy Technologies and Assessments, 2021
Due to reduction of feed in tariff, the exploration of design solutions for smart cost-effective ... more Due to reduction of feed in tariff, the exploration of design solutions for smart cost-effective energy system is required to enable the consumers to select the optimum capacity of renewable energy system. This study investigates an innovative reward-penalty mechanism which is specifically designed to promote net zero energy buildings and net zero energy communities. Two different strategies (i.e. the building-level-based strategy and the community-level-based strategy) are developed regarding the application of the proposed reward-penalty mechanism. The electricity loads of family-houses in Ireland ranging from 1,286 kWh/y to 36,802 kWh/y are used to study the effect of the proposed strategies. The results show that both strategies lead to a similar cost versus zero-energy-building level relationship, i.e. a higher profit is related to a higher zero-energy-building level whilst a heavier financial penalty is related to a lower zero-energy-building level. The difference between the costs for the entire community (100 family-houses) predicted by the two different strategies is observed to be less than 10%. The building-level-based strategy is observed to produce the change rate of cost versus zero-energy-building level curve that often deviates significantly from the expected parabolic curve designed in this study, thus the community-level-based strategy provides an advantage over the building-level-based strategy. In addition, the Monte Carlo sampling method is used to quantify the uncertainty of the proposed reward-penalty function. © 2021 Elsevier Lt
![Research paper thumbnail of Errata to “Analysis on the Effect of a Nonuniform Inlet Profile on Heat Transfer and Fluid Flow in Turbine Stages” [Journal of Turbomachinery, 134(1), 011012]](https://attachments.academia-assets.com/95858014/thumbnails/1.jpg)
](Journal of Turbomachinery, 2013
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 2011
Tighter aircraft emissions regulations have let to considerable improvement in gas turbine combus... more Tighter aircraft emissions regulations have let to considerable improvement in gas turbine combustion in the past few decades. Modern combustors employ aggressive swirlers to increase mixing and to improve flame stability during the combustion process. The flow at combustor exit can therefore have high residual swirl. The impact of this swirl on the aerodynamic and heat transfer characteristics of the HP turbine stage has not yet received much attention. In order to investigate the effects of swirl on the HP turbine stage, an inlet swirl simulator has been designed and commissioned in an engine scale, short duration, rotating transonic turbine facility. The test facility simulates engine representative Mach number, Reynolds number, non-dimensional speed and gas-to-wall temperature ratio at the turbine inlet. The target swirl profile at turbine stage inlet was based upon extreme exit swirl conditions for a modern low-NO x combustor with peak yaw and pitch angles over ±40°. A number o...
Journal of Turbomachinery, 2012
Swirling flows are now widely being used in modern gas turbine combustors to improve the combusti... more Swirling flows are now widely being used in modern gas turbine combustors to improve the combustion characteristics, flame stability, and reduce emissions. Residual swirl at the combustor exit will affect the performance of the downstream high-pressure (HP) turbine. In order to perform a detailed investigation of the effect of swirl on a full-scale HP turbine stage, a combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK, as the Turbine Test Facility (TTF). The swirl simulator is capable of generating engine-representative combustor exit swirl distributions at the turbine inlet, with yaw and pitch angles of up to 6 40 deg. The turbine test facility is an engine scale, short duration, rotating transonic turbine facility, which simulates the engine representative M, Re, Tu, nondimensional speed, and gas-to-wall temperature ratio at the turbine inlet. The test turbine is a highly loaded unshrouded design (the MT1 turbine). This paper presents time-averaged experimental heat transfer measurements performed on the rotor casing surface, and on the rotor blade surface at 10%, 50%, and 90% span. Time-averaged rotor casing static pressure measurements are also presented. Experimental measurements with and without inlet swirl are compared. The measurements are discussed with the aid of three-dimensional steady and unsteady CFD simulations of the turbine stage. Numerical simulations were conducted using the Rolls-Royce in-house code HYDRA, with and without inlet swirl.
Journal of Turbomachinery, 2012
Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve... more Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve flame stability. The flow at combustor exit can therefore have high residual swirl. A good deal of research concerning the flow within the combustor is available in open literature. The impact of swirl on the aerodynamic and heat transfer characteristics of an HP turbine stage is not well understood, however. A combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK. The swirl simulator is capable of generating an engine-representative combustor exit swirl pattern. At the turbine inlet plane, yaw and pitch angles of over 640 deg have been simulated. The turbine research facility used for the study is an engine scale, short duration, rotating transonic turbine, in which the nondimensional parameters for aerodynamics and heat transfer are matched to engine conditions. The research turbine was the unshrouded MT1 design. By design, the center of the vortex from the swirl simulator can be clocked to any circumferential position with respect to HP vane, and the vortex-to-vane count ratio is 1:2. For the current investigation, the clocking position was such that the vortex center was aligned with the vane leading edge (every second vane). Both the aligned vane and the adjacent vane were characterized. This paper presents measurements of HP vane surface and end wall heat transfer for the two vane positions. The results are compared with measurements conducted without swirl. The vane surface pressure distributions are also presented. The experimental measurements are compared with full-stage three-dimensional unsteady numerical predictions obtained using the Rolls Royce in-house code Hydra. The aerodynamic and heat transfer characterization presented in this paper is the first of its kind, and it is hoped to give some insight into the significant changes in the vane flow and heat transfer that occur in the current generation of low NO x combustors. The findings not only have implications for the vane aerodynamic design, but also for the cooling system design.
… of the Institution of Mechanical Engineers, …, Jan 1, 2008
Journal of Turbomachinery, Jan 1, 2009
Journal of Engineering for Gas Turbines …, Jan 1, 2011
This paper presents an investigation of the aerothermal performance of a modern unshrouded high-p... more This paper presents an investigation of the aerothermal performance of a modern unshrouded high-pressure (HP) aero-engine turbine subject to nonuniform inlet temperature profile. The turbine used for this study was the MT1 turbine installed in the QinetiQ turbine test facility based ...
International Journal of Precision Engineering and Manufacturing-Green Technology, 2019
Titanium alloys are generally known as difficult-to-machine materials because of their low machin... more Titanium alloys are generally known as difficult-to-machine materials because of their low machinability ratings. Their usage is favored for demanding sectors because of their high strength to weight ratio, high corrosion resistance and ability to operate at elevated temperatures. Machining of titanium alloys results in higher environmental burden, because they require high energy and generous amount of cutting fluids during machining. It is a well-known fact that most of the cutting fluids are toxic and non-biodegradable in nature and their disposal is costly. Therefore, researchers in metal cutting are keen to explore the potential of minimum quantity lubrication (MQL) and minimum quantity cooling lubrication (MQCL) based cooling techniques as an alternate to conventional flood cooling. When MQL and MQCL techniques are used by employing biodegradable vegetable based oils then there is an encouraging potential of replacing the non-biodegradable cutting fluids. This study documents the recent experimental and numerical advances achieved in the MQL and MQCL assisted techniques for machining titanium alloys. The study also highlights the current challenges in this area and recommends future work to address these challenges.
Flow Measurement and Instrumentation, 2019
The range of flow angles that can be measured accurately using multi-hole probes is restricted du... more The range of flow angles that can be measured accurately using multi-hole probes is restricted due to limitations, such as singularity, in the calibration techniques used. Several modified techniques have been proposed for five and seven-hole probes to extend their usable range of operation. However fewer techniques are available in the literature for four-hole probe, which has an advantage over its counterparts because of its smaller size. This research fills the gap by reviewing the techniques implemented successfully on either five or seven-hole probes operating in non-nulling mode to extend their calibration maps and then adapting those techniques for four-hole probes. Three techniques, in addition to the traditional technique, are adapted for a four-hole probe by suitable modification. The adapted techniques have been implemented on the calibration data set of actual flow angles and raw pressures from a four-hole probe. The results from the validation of all three techniques are compared with the results from traditional technique to evaluate the resulting extension in the calibration maps. Overall, all methods showed an extension in the region of usable calibration map compared to the traditional technique. However, the results showed an advantage for the new zonal method technique, which offered a significant extension in the calibration map of a four-hole probe. It is the first time that such a consolidated effort has been done to extend the calibration map of a four-hole probe for measuring high flow angles.
Sustainable Energy Technologies and Assessments, 2021
Due to reduction of feed in tariff, the exploration of design solutions for smart cost-effective ... more Due to reduction of feed in tariff, the exploration of design solutions for smart cost-effective energy system is required to enable the consumers to select the optimum capacity of renewable energy system. This study investigates an innovative reward-penalty mechanism which is specifically designed to promote net zero energy buildings and net zero energy communities. Two different strategies (i.e. the building-level-based strategy and the community-level-based strategy) are developed regarding the application of the proposed reward-penalty mechanism. The electricity loads of family-houses in Ireland ranging from 1,286 kWh/y to 36,802 kWh/y are used to study the effect of the proposed strategies. The results show that both strategies lead to a similar cost versus zero-energy-building level relationship, i.e. a higher profit is related to a higher zero-energy-building level whilst a heavier financial penalty is related to a lower zero-energy-building level. The difference between the costs for the entire community (100 family-houses) predicted by the two different strategies is observed to be less than 10%. The building-level-based strategy is observed to produce the change rate of cost versus zero-energy-building level curve that often deviates significantly from the expected parabolic curve designed in this study, thus the community-level-based strategy provides an advantage over the building-level-based strategy. In addition, the Monte Carlo sampling method is used to quantify the uncertainty of the proposed reward-penalty function. © 2021 Elsevier Lt
Journal of Turbomachinery, 2013
Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, 2011
Tighter aircraft emissions regulations have let to considerable improvement in gas turbine combus... more Tighter aircraft emissions regulations have let to considerable improvement in gas turbine combustion in the past few decades. Modern combustors employ aggressive swirlers to increase mixing and to improve flame stability during the combustion process. The flow at combustor exit can therefore have high residual swirl. The impact of this swirl on the aerodynamic and heat transfer characteristics of the HP turbine stage has not yet received much attention. In order to investigate the effects of swirl on the HP turbine stage, an inlet swirl simulator has been designed and commissioned in an engine scale, short duration, rotating transonic turbine facility. The test facility simulates engine representative Mach number, Reynolds number, non-dimensional speed and gas-to-wall temperature ratio at the turbine inlet. The target swirl profile at turbine stage inlet was based upon extreme exit swirl conditions for a modern low-NO x combustor with peak yaw and pitch angles over ±40°. A number o...
Journal of Turbomachinery, 2012
Swirling flows are now widely being used in modern gas turbine combustors to improve the combusti... more Swirling flows are now widely being used in modern gas turbine combustors to improve the combustion characteristics, flame stability, and reduce emissions. Residual swirl at the combustor exit will affect the performance of the downstream high-pressure (HP) turbine. In order to perform a detailed investigation of the effect of swirl on a full-scale HP turbine stage, a combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK, as the Turbine Test Facility (TTF). The swirl simulator is capable of generating engine-representative combustor exit swirl distributions at the turbine inlet, with yaw and pitch angles of up to 6 40 deg. The turbine test facility is an engine scale, short duration, rotating transonic turbine facility, which simulates the engine representative M, Re, Tu, nondimensional speed, and gas-to-wall temperature ratio at the turbine inlet. The test turbine is a highly loaded unshrouded design (the MT1 turbine). This paper presents time-averaged experimental heat transfer measurements performed on the rotor casing surface, and on the rotor blade surface at 10%, 50%, and 90% span. Time-averaged rotor casing static pressure measurements are also presented. Experimental measurements with and without inlet swirl are compared. The measurements are discussed with the aid of three-dimensional steady and unsteady CFD simulations of the turbine stage. Numerical simulations were conducted using the Rolls-Royce in-house code HYDRA, with and without inlet swirl.
Journal of Turbomachinery, 2012
Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve... more Modern lean burn combustors now employ aggressive swirlers to enhance fuel-air mixing and improve flame stability. The flow at combustor exit can therefore have high residual swirl. A good deal of research concerning the flow within the combustor is available in open literature. The impact of swirl on the aerodynamic and heat transfer characteristics of an HP turbine stage is not well understood, however. A combustor swirl simulator has been designed and commissioned in the Oxford Turbine Research Facility (OTRF), previously located at QinetiQ, Farnborough UK. The swirl simulator is capable of generating an engine-representative combustor exit swirl pattern. At the turbine inlet plane, yaw and pitch angles of over 640 deg have been simulated. The turbine research facility used for the study is an engine scale, short duration, rotating transonic turbine, in which the nondimensional parameters for aerodynamics and heat transfer are matched to engine conditions. The research turbine was the unshrouded MT1 design. By design, the center of the vortex from the swirl simulator can be clocked to any circumferential position with respect to HP vane, and the vortex-to-vane count ratio is 1:2. For the current investigation, the clocking position was such that the vortex center was aligned with the vane leading edge (every second vane). Both the aligned vane and the adjacent vane were characterized. This paper presents measurements of HP vane surface and end wall heat transfer for the two vane positions. The results are compared with measurements conducted without swirl. The vane surface pressure distributions are also presented. The experimental measurements are compared with full-stage three-dimensional unsteady numerical predictions obtained using the Rolls Royce in-house code Hydra. The aerodynamic and heat transfer characterization presented in this paper is the first of its kind, and it is hoped to give some insight into the significant changes in the vane flow and heat transfer that occur in the current generation of low NO x combustors. The findings not only have implications for the vane aerodynamic design, but also for the cooling system design.
… of the Institution of Mechanical Engineers, …, Jan 1, 2008
Journal of Turbomachinery, Jan 1, 2009
Journal of Engineering for Gas Turbines …, Jan 1, 2011
This paper presents an investigation of the aerothermal performance of a modern unshrouded high-p... more This paper presents an investigation of the aerothermal performance of a modern unshrouded high-pressure (HP) aero-engine turbine subject to nonuniform inlet temperature profile. The turbine used for this study was the MT1 turbine installed in the QinetiQ turbine test facility based ...