A new project has begun to examine the possibility of cooling the planet by means of Solar Radiation Management (SRM) . This work was prompted by a report from The Royal Society which recommended that geoengineering research be a UK priority. The EPSRC has funded the SPICE project to the tune of £1.8. The SPICE project investigates the benefits, risks, costs and feasibility of SRM through the deployment of reflective aerosols in the stratosphere. It addresses the three grand challenges: 1. How much, of what, needs to be injected where into the atmosphere to effectively and safely manage the climate system? 2. How do we deliver it there? 3. What are the likely impacts? These questions are addressed through three coordinated and inter-linked work packages which are summarised at SPICE ). We propose that particles can be delivered to the stratosphere through a high-pressure pipe suspended by a balloon tethered at an altitude of 20km. An ultra-high pressure pumping system would deliver a particulate slurry to be dispersed at altitude. The resulting particulate cloud would then lead to global cooling by increasing the albedo of the planet in just the same way as the planet cools after a large volcanic eruption. The feasibility of the SPICE system depends upon the long-term deployment globally of a small number of (say 60) balloons each delivering 5kg/s of aerosol - an estimated 10 million tonnes per year (for context, consider that global manmade CO2 output is 30,000 million tonnes per year). Our research examines the dynamics and stability of a proposed tethered aerostat at an altitude of 20km. The tether is to be 22km in length and is to be fixed to a ship at sea. High wind velocities of up to 300km/h can be experienced in the upper atmosphere, especially in the jet stream. A tether of circular cross section in these high winds will be subject to horizontal and downward drag forces that can act to bring the aerostat down. For this reason it is advantageous to consider a tether of an aerodynamic cross section whereby it is possible to reduce the drag substantially. One disadvantage of a non-circular tether is the possibility of flutter and galloping instabilities.
Despite use of the best in current design practices, high-speed shaft (HSS) bearings, in a wind-turbine gearbox, continue to exhibit a high rate of premature failure. As HSS bearings operate under low loads and high speeds, these bearings are prone to skidding. However, most of the existing methods for analyzing skidding are quasi-static in nature and cannot be used to study dynamic operating conditions. This paper proposes a dynamic model, which includes gyroscopic and centrifugal effects, to study the skidding characteristics of angular-contact ball-bearings. Traction forces between rolling-elements and raceways are obtained using elastohydrodynamic (EHD) lubrication theory. Underlying gross-sliding mechanisms for pure axial loads, and combined radial and axial loads are also studied. The proposed model will enable engineers to improve bearing reliability at the design stage, by estimating the amount of skidding.
The purpose of this project is to develop a method of including the effect of random mistuning into the analysis of turbocharger wheel geometry in order to assess the effect of mistuning on the performance and life of the wheel.
Recent expansion of high-speed railway networks has raised concern surrounding the generation of vibration by railway operations vibration isolation. Current work in the Department centres on the transmission of vibration from underground railways into buildings. The railway and adjacent buildings are modelled as structures of infinite length and this greatly simplifies the computation of vibration spectra. This work has resulted in the development of PiP , computationally-efficient software for the prediction of vibration from underground railways.
Wind and wave power are two of the UK's most promising sources of sustainable energy. As the need to reduce demand on carbon-based fuels progresses the need to develop simple and effective wave-power and wind-power devices grows. My research has led to the formation of OceeanGyro, a small company that is developing a modular gyroscopic wave-energy device. In addition I work to improve reliability and to reduce noise of wind turbines