Contrail formation remains one of the least understood yet most climate-relevant impacts of aviation. Persistent contrails can evolve into cirrus-like clouds that significantly affect Earth's radiative balance, but the physical mechanisms governing their formation particularly in the near-field region immediately downstream of aircraft engines remain poorly characterised. This fully funded PhD studentship is part of a Leverhulme Trust Research Project entitled Bridging the scale gap: From non-equilibrium thermodynamics to contrails. The project combines laboratory-scale experiments with high-fidelity numerical modelling to investigate vapour-liquid-solid phase transitions in aircraft exhaust plumes under controlled conditions, with particular relevance to emerging low-soot propulsion technologies such as sustainable aviation fuels and hydrogen. The PhD project focuses on the experimental investigation of early contrail formation, using a dedicated facility that generates contrail-relevant exhaust flows by injecting a high-speed moist jet into a controlled, cold environment. The student will contribute to the development and application of advanced optical and laser-based diagnostics to characterise condensation, freezing, and particle populations in the evolving plume. The project includes close interaction with numerical simulations, enabling quantitative comparison between experiment and CFD and supporting physical interpretation of the measured processes. While the primary focus of the PhD is experimental, the student will gain experience working at the interface of experiment and high-fidelity modelling in a collaborative research environment. Applicants should have (or expect to obtain by the start date) at least a good 2.1 degree in Engineering or a related discipline, and a strong interest in experimental fluid dynamics. Experience with laboratory instrumentation, data acquisition, and coding for experiment control or data analysis (e.g. LabVIEW, MATLAB, or Python) would be beneficial. Applicants should have (or expect to obtain by the start date) at least a good 2.1 degree in Engineering or a closely related subject. A strong interest in experimental fluid mechanics and thermodynamics is essential. The project involves multiphase and particle-laden flows relevant to contrail formation; prior experience in these areas is welcome but not required. Experience with laboratory instrumentation, data acquisition, or optical diagnostics is desirable but not essential. Familiarity with coding or data analysis (e.g. MATLAB, Python, LabVIEW) would be an advantage. Good written and spoken English communication skills are expected. The studentship is fully funded and includes tuition fees and a tax-free stipend at the UKRI rate. The expected start date is 1 October 2026. Applications should include a CV, academic transcripts, and a brief statement outlining the applicant's motivation and relevant background. Informal enquiries are welcome. Applications should be submitted via the University of Cambridge Applicant Portal https://www.postgraduate.study.cam.ac.uk/courses/directory/egegpdpeg/finance, with Andrew Wheeler ( aw329@cam.ac.uk ) identified as the potential supervisor. Applications may close early if the position is filled before the advertised date. Please note there is a £20 application fee attached to using the Cambridge Applicant Portal. Informal enquiries can be made to either Andrew Wheeler ( aw329@cam.ac.uk ) or Katharina Tegethoff ( kt568@cam.ac.uk ) The University actively supports equality, diversity and inclusion and encourages applications from all sections of society. Key information