Department of Mechanical Engineering

Image of Dr David Cleaver

Contact details

Room: 4E 2.42
Tel: +44 (0) 1225 385776
Email: d.j.cleaver@bath.ac.uk

Personal website

PhD supervision

Interested in supervising students studying:

  • Active flow control for wind turbines
  • Unsteady aerodynamics
  • Drag reduction techniques.

Dr David Cleaver

MEng, PhD

Profile

Dr Cleaver is a lecturer in Aerospace Engineering in the Department of Mechanical Engineering.

David started studying for a MEng in Aerospace Engineering in 2003, before going onto start a PhD in the field of experimental unsteady aerodynamics in 2007.

On graduation he went on to continue in the same field as a post-doctoral researcher, and then was awarded a lectureship of computational engineering at the University of Bath in 2012.

Research

David's research is within the field of unsteady aerodynamics. This is an exciting and novel research area which attempts to move beyond classic 'steady-state' aerodynamics so as to improve the efficiency of all forms of fluid dynamic device, from aircraft to gas turbines. In essence, all aero/ fluid dynamic problems are actually unsteady (variation with time) aerodynamic problems, but are usually assumed to be steady (constant with time).

This gap in understanding not only leads to inaccuracy but also lost opportunities. It is these lost opportunities that the unsteady aerodynamics community are trying to exploit through devices such as: plasma actuators, synthetic jet actuators, fluid-structure interactions, and so on.

Previously this research has focused on low Reynolds number oscillating rigid or plunging airfoils applicable to Micro Air Vehicles (MAVs). MAVs are small (<15cm) remote craft suited to search and rescue / reconnaissance applications, however currently there are no practical examples due to the challenges of low Reynolds number (small scale) aerodynamics.

This work took the example of natural flyers (birds / insects), but instead of using large-amplitude low frequency plunging motions it applied small-amplitude high-frequency motion which is more suited to electrical actuators.The results showed up to a 300 per cent increase in lift and thrust. In addition, the results elucidated several fundamental fluid dynamic phenomena such as new modes of vortex behaviour and wake bifurcations.

Currently the focus of David's work is on the application of unsteady aerodynamics to wind turbines. One of the major challenges facing wind turbine development is the large unsteady aerodynamic forces experienced by the blades in both their extreme-load and fatigue-load cases. mActive flow control presents a viable method of limiting these at the first point of contact, the fluid-structure interface, allowing operation at higher wind speeds with larger blades. In addition, appropriate actuation could also increase yields at low wind speeds expanding the performance envelope in all directions.

Teaching units

  • Advanced Helicopter Dynamics

Publications

Articles

Jones, R., Cleaver, D. and Gursul, I., 2017. Stall delay of two-wing configurations with decalage at low Reynolds numbers. AIAA Journal of Aircraft, 54 (2), pp. 847-852.

Cleaver, D., Calderon, D.E., Wang, Z. and Gursul, I., 2016. Lift enhancement through flexibility of plunging wings at low Reynolds numbers. Journal of Fluids and Structures, 64, pp. 27-45.

Jones, R., Cleaver, D. J. and Gursul, I., 2015. Aerodynamics of biplane and tandem wings at low Reynolds numbers. Experiments in Fluids, 56 (6), 124.

Cleaver, D., Gursul, I., Calderon, D. and Wang, Z., 2014. Thrust enhancement due to flexible trailing-edge of plunging foils. Journal of Fluids and Structures, 51, pp. 401-412.

Calderon Robayo, D., Cleaver, D. J., Gursul, I. and Wang, Z., 2014. On the absence of asymmetric wakes for periodically plunging finite wings. Physics of Fluids, 26, 071907.

Gursul, I., Cleaver, D. J. and Wang, Z., 2014. Control of low Reynolds number flows by means of fluid–structure interactions. Progress in Aerospace Sciences, 64, pp. 17-55.

Cleaver, D., Wang, Z. and Gursul, I., 2013. Investigation of mechanisms of high lift for a flat-plate airfoil undergoing small-amplitude plunging oscillations. AIAA Journal, 51 (4), pp. 968-980.

Cleaver, D., Calderon, D. E., Wang, Z. and Gursul, I., 2013. Periodically plunging foil near a free surface. Experiments in Fluids, 54 (3), 1491.

Cleaver, D. J., Wang, Z. and Gursul, I., 2012. Bifurcating flows of plunging airfoils at high Strouhal numbers. Journal of Fluid Mechanics, 708, pp. 349-376.

Cleaver, D. J., Wang, Z., Gursul, I. and Visbal, M. R., 2011. Lift enhancement by means of small-amplitude airfoil oscillations at low Reynolds numbers. AIAA Journal, 49 (9), pp. 2018-2033.

Conference or Workshop Items

Chiereghin, N., Cleaver, D. and Gursul, I., 2017. Unsteady force and flow measurements for plunging finite wings. In: 47th AIAA Fluid Dynamics Conference, 2017-06-05 - 2017-06-09, Denver.

Heathcote, D., Gursul, I. and Cleaver, D., 2017. Frequency Response of Aerodynamic Load Control through Mini-tabs. In: 55th AIAA Aerospace Sciences Meeting, 2017-01-09 - 2017-01-13, Gaylord Texan. American Institute of Aeronautics and Astronautics.

Chiereghin, N., Cleaver, D. and Gursul, I., 2017. Unsteady Measurements for a Periodically Plunging Airfoil. In: 55th AIAA Aerospace Sciences Meeting, 2017-01-09 - 2017-01-13, Gaylord Texan.

Lai, G., Plummer, A., Cleaver, D. and Zhou, H., 2016. Parallel kinematic mechanisms for distributed actuation of future structures. In: 13th International Conference on Motion and Vibration Control, 2016-07-03 - 2016-07-06, University of Southampton.

Cleaver, D., Chiereghin, N., Heathcote, D., Bull, S. and Gursul, I., 2016. Unsteady Aerodynamic Loads and Their Control through Mini-tab Actuation. In: Vertical Lift Network 2nd Annual Workshop, 2016-05-09 - 2016-05-10, Shrigley Hall.

Al-Battal, N., Cleaver, D. and Gursul, I., 2016. Aerodynamic Load Control through Blowing. In: AIAA SciTech 2016, 2016-01-04 - 2016-01-08, Manchester Grand Hyatt, San Diego, California.

Heathcote, D., Gursul, I. and Cleaver, D., 2016. An Experimental Study of Mini-Tabs for Aerodynamic Load Control. In: AIAA SciTech 2016, 2016-01-04 - 2016-01-08, Manchester Grand Hyatt, San Diego, California.

Heathcote, D., Al-Battal, N., Gursul, I. and Cleaver, D., 2015. Control of Wing Loads by Means of Blowing and Mini-Tabs. In: European Drag Reduction and Flow Control Meeting, 2015-03-23 - 2015-03-25, Sidney Sussex College, Cambridge.

Jones, R., Cleaver, D. and Gursul, I., 2015. Fluid-structure interactions for flexible and rigid tandem-wings at low Reynolds numbers. In: 53rd AIAA Aerospace Sciences Meeting (AIAA SciTech 2015), 2015-01-05. American Institute of Aeronautics and Astronautics.

Cleaver, D., Wang, Z. and Gursul, I., 2013. Oscillating flexible wings at low Reynolds numbers. In: 51st AIAA Aerospace Sciences Meeting, 2013-01-07 - 2013-01-10.

Cleaver, D. J., Calderon, D.E., Wang, Z. and Gursul, I., 2013. Low aspect ratio oscillating flexible wings at low Reynolds numbers. In: 43rd AIAA Fluid Dynamics Conference, 2013-06-24 - 2013-06-27.

Calderon, D.E., Cleaver, D. J., Wang, Z. and Gursul, I., 2013. Wake structure of plunging finite wings. In: 43rd AIAA Fluid Dynamics Conference, 2013-06-24 - 2013-06-27.

Cleaver, D., Wang, Z. and Gursul, I., 2012. Effect of airfoil shape on flow control by small-amplitude oscillations. In: 50th AIAA Aerospace Sciences Meeting Including The New Horizons Forum and Aerospace Exposition, 2012-01-09 - 2012-01-12.

Cleaver, D., Calderon Robayo, D., Wang, Z. and Gursul, I., 2012. Rigid and Flexible Foils Oscillating Near a Free Surface. In: 50th AIAA Aerospace Sciences Meeting Including The New Horizons Forum and Aerospace Exposition, 2012-01-09 - 2012-01-12.

Cleaver, D. J., Wang, Z. and Gursul, I., 2010. Vortex mode bifurcation and lift force of a plunging airfoil at low reynolds numbers. In: 48th AIAA Aerospace Sciences Meeting, 2010-01-07 - 2010-01-10.

Cleaver, D., Wang, Z. and Gursul, I., 2009. Lift enhancement on oscillating airfoils. In: 39th AIAA Fluid Dynamics Conference, 2009-06-22 - 2009-06-25.

Cleaver, D., Wang, Z. and Gursul, I., 2009. Delay of stall by small amplitude airfoil oscillation at low reynolds numbers. In: 47th AIAA Aerospace Sciences Meeting, 2009-01-05 - 2009-01-08.

Thesis

Cleaver, D., 2011. Low Reynolds number flow control through small-amplitude high-frequency motion. Thesis (Doctor of Philosophy (PhD)). University of Bath.

Non-academic press

Iravani, P., Cleaver, D. and Du Bois, J., 2015. The design decisions behind Amazon’s strange-looking delivery drone. The Conversation

This list was generated on Thu Oct 19 22:41:43 2017 IST.