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Details of Grant 

EPSRC Reference: EP/N009037/1
Title: High Response Diamond Based Heat Transfer Gauge Development
Principal Investigator: McGilvray, Dr M
Other Investigators:
Researcher Co-Investigators:
Project Partners:
Element Six Fluid Gravity Engineering Ltd Japan Aerospace Exploratory Agency
The European Space Research and Tech Ctr
Department: Engineering Science
Organisation: University of Oxford
Scheme: First Grant - Revised 2009
Starts: 10 November 2015 Ends: 09 May 2017 Value (£): 99,395
EPSRC Research Topic Classifications:
Aerodynamics Design & Testing Technology
Heat & Mass Transfer
EPSRC Industrial Sector Classifications:
Aerospace, Defence and Marine
Related Grants:
Panel History:
Panel DatePanel NameOutcome
05 Aug 2015 Engineering Prioritisation Panel Meeting 5 August 2015 Announced
Summary on Grant Application Form
Humans' exploration of solar system brings one of the most challenging engineering feats, the design of spacecraft which can survive extreme heat loads while re-entering Earth's atmosphere, such as recent asteroid sample return mission Hyabusa, and to enter other planets atmospheres such as the Mars Science Laboratory. Currently, large uncertainties exist in the expected flight heat loads leading to spacecraft heat shields which are much heavier than necessary when every gram is critical. This projects aims to build a novel high response diamond based heat transfer sensor which can be used to accurately measure the heat transfer on subscale spacecraft models in high speed wind tunnels.

To slow a spacecraft to either enter into planetary orbit or land on the surface, aerodynamic braking in the planet's atmosphere causes a conversion of the vehicles kinetic energy to thermal energy, generating gas temperatures hotter than the surface of the sun (6000 degrees C) in front of the vehicle. This results in enormous heat transfer to the vehicle, in excess of 100's MW/m2. This requires the vehicle to use thermal protection systems (TPS), which apply advanced ablating materials which limits the heat conduction to the spacecraft's structure. As the TPS adds significantly to the lift-off mass, any reduction in TPS will result in an increase in available payload to achieve mission objectives or reduce launch costs while increasing reliability.

To directly replicate the flow conditions experienced in spacecraft entry in a ground based wind tunnel is extremely difficult due to the high energy and pressures involved. This has led to engineers developing impulsive wind tunnels, which generate appropriate flow conditions for periods on the order of milliseconds by a cascade of high energy processes. Current heat transfer measurement techniques for impulsive high speed wind tunnels have been shown to be inadequate in measuring the heat fluxes in the front of subscale models in these tunnels due to slow time response (thermocouples, IR) or are damaged by particulates and have interference from the ionised flow field (thin film heat transfer and atomic layer thermopiles).

Diamond is an incredible material, and has unique combination of thermal properties allow it to be used as a very fast acting calorimeter up to 1 MHz. The gauge measures the temperature rise of a thin piece of diamond (50-500 micrometres), and by measuring the temperature rise on the rear side of the diamond using thin film gauges, this protects the electronics from particle debris and the ionised gas, and also high accuracy. For the high heat transfer rates seen on spacecraft, the temperature rise achieved would be appropriate for reliable measurement using current thin film resistive gauge technology.

In summary, this project will develop and test diamond based heat transfer gauges for application in accurately measuring heat transfer rates on spacecraft models. This aligns with the EPSRC research areas of both Sensor development and Fluid Dynamics research, with the proposed research both having direct impact, as well as facilitating research into the future.

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Organisation Website: http://www.ox.ac.uk