Open Testcases (DLR)
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The Institute of Space Propulsion of the DLR provides the following testcases:
- Testcase HF-1/4: Damping in Cavities,
- Testcase HF-6: LOX/H2-Combustion under Forced Acoustic Excitation,
- Testcase HF-7: LOX/H2-Combustion with Self-Sustained Acoustic Excitation,
- Testcase HT-1: Heat Transfer in Cooling Channels with H2 and CH4 and
- Testcase IN-1: Droplet Characterization in Cryogenic Flash Boiling Liquid Nitrogen Sprays at High-altitude Conditions.
If you are interested in using the data, please download the corresponding license agreement. Please return the signed license agreement to us afterwards. We will then provide you with a download of the data.
The testcase HF-1/4 serves to evaluate the ability of simulation tools to predict the acoustic attenuation in a combustion chamber equipped with λ/4 absorbers. The combustion chamber is filled with air and there is no convective flow. At low acoustic disturbances, the main damping mechanism is viscous and thermal dissipation in the acoustic boundary layers. Since the thickness of these boundary layers in rocket engines is typically less than 0.1 mm, the computational effort to resolve such boundary layers is unaffordable for industrial tools and the dissipation mechanisms must be modeled.
The DLR has carried out extensive experimental measurements of the "cold" damping of the "Common Research Chamber" (CRC), which has a cylindrical geometry and is equipped with one or more damping cavities of variable length.
Oschwald, M., Farago, Z., Searby, G. "Resonance frequencies and damping of a cylindrical combustor acoustically coupled to an absorber", Journal of Propulsion and Power, Vol. 24, pp. 524-533, 2007
The purpose of the testcase is to verify the predictability of numerical simulation tools for thermo-acoustic interactions in rocket combustion chambers. The conditions in the combustion chamber are representative for upper stage engines.
At the DLR Institute of Space Propulsion the combustion chamber BKH is used to experimentally investigate the interaction of LOX/H2 combustion and acoustics. The experiments on which this testcase is based were carried out on the P8 test bench for cryogenic high-pressure combustion.
The BKH has a rectangular cross-section and can be excited with a siren at acoustic frequencies typical for high frequency instabilities. The combustion chamber can be operated at pressures up to 60 bar, i.e. oxygen at supercritical pressure. The five injection elements are representative of upper stage engines in terms of dimension, flow rate and configuration. Windows allow optical access to the combustion chamber.
Tests have so far been conducted with hydrogen as fuel at ambient and low temperatures. High-speed visualization was used to capture the spatial and temporal response of the LOX spray and flame to the forced acoustic excitation.
- Hardi, J., Oschwald, M., Dally, B. "Flame response to acoustic excitation in a rectangular rocket combustor with LOX/LH2 propellants", CEAS Space Journal, 2, 2011, pp. 41–49
- Hardi, J., Oschwald, M., Dally, B. "Acoustic characterisation of a rectangular rocket combustor with liquid oxygen and hydrogen propellants", Proceedings of the Institution of Mechanical Engineers, Part G: Journal of Aerospace Engineering, Volume 227, Issue 3, March 2013, Pages 436-446
- Hardi, J., Beinke, S., Oschwald, M., Dally, B. "Coupling of LOX/H2 Flames to Longitudinal and Transverse Acoustic Instabilities", Journal of Propulsion and Power, Vol. 30, No.4, 2014
- Hardi, J., Gomez Martinez, H.C., Oschwald, M. "LOX Jet Atomization under Transverse Acoustic Oscillation", Journal of Propulsion and Power, Vol. 30, No. 2, pp. 337-349, 2014
- Webster, S., Hardi, J., Oschwald, M. "Characterization of Acoustic Energy Content in an Experimental Combustion Chamber with and without External Forcing", CEAS Space Journal, Vol. 7, pp. 37-51, 2015
- Hardi, J., Oschwald, M. "Cryogenic Oxygen Jet Response to Transverse Acoustic Excitation With the First Transverse and the the First Combined Longitudinal –Transverse Modes", Progress in Propulsion Physics, Vol. 8, pp. 75-94, 2016
- Webster, S., Hardi, J., Oschwald, M. "Measurement of Acoustic Dissipation in an Experimental Combustor Under Representative Conditions", Journal of Sound and Vibration, Vol. 390, pp. 39-54, 2017
- Webster, S. "Analysis of Pressure Dynamics, Forced Excitation and Damping in a High Pressure LOX/H2 Combustor", Dissertation, RWTH Aachen University, Germany, 2016
The cylindrical combustion chamber D (BKD) has an injection head with 42 coaxial injectors and is operated with liquid oxygen and hydrogen at pressures of up to 80 bar. In test campaigns specifically designed to investigate the stability behaviour of the combustion chamber as a function of the operating conditions, it was found that the BKD can be operated both at stable load points and at load points with self-excited high-frequency acoustic excitations.
Due to the complexity of the test setup, the testcase was divided into three parts. The objectives of this first part focus on the acoustic eigenmodes, their amplitudes and their damping for two selected operating points LP1 and LP2. In the second part the amplitude of the oscillations of the 1T-mode and the line width of the 1T-mode shall be simulated for these two load points.In the third part, the simulations of parts one and two shall be applied to the two load points LP3 and LP4. The two load points of the third stage are characterised by a colder hydrogen temperature.
- Gröning, S., Hardi, J., Suslov, D., Oschwald, M. "Influence of hydrogen temperature on the stability of a rocket engine combustor operated with hydrogen and oxygen", CEAS Space Journal, Vol. 9, pp. 59-76, 2017
- Gröning, S., Hardi, J., Suslov, D., Oschwald, M. "Injector-Driven Combustion Instabilities in a Hydrogen/Oxygen Rocket Combustor", Journal of Propulsion and Power, Vol. 32, pp. 560-573
- Gröning, S., Hardi, J., Suslov, D., Oschwald, M. "Analysis of phase shift between oscillations of pressure and flame radiation intensity of self-excited combustion instabilities", 6th EUCASS, Krakow, Poland, 2015
- Gröning, S., Hardi, J., Suslov, D., Oschwald, M. "Influence of hydrogen temperature on the acoustics of a rocket engine combustion chamber operated with LOX/H2 at representative conditions", Space Propulsion Conference, Cologne, Germany, 2014
- Gröning, S. "Untersuchung selbsterregter Verbrennungsinstabilitäten in einer Raketenbrennkammer", Dissertation, RWTH Aachen University, Germany, 2017
The HARCC testcase makes experimental results available to improve numerical simulation tools to predict the heat transfer in cooling channels of regenerative cooled thrust chambers. The conditions are representative for upper stage engines.
The combustion chamber BKD with the HARCC-segment is used to experimentally study the cooling capabilities of hydrogen and methane in rocket engines. The experiments for this testcase took place at the P8 test bench in Lampoldshausen.
The HARCC-Segment is a cylindrical combustion chamber segment that is divided into four sectors around the circumference, each containing certain cooling channel geometry. Those are rectangular cooling channel with different aspect ratio (height-to-width ratio) ranging from 1.7 (Q1) up to 30 (Q3). One goal of the test campaign was the investigation of thermal stratification that occurs in cooling channels with a high aspect ratio. For methane as cooling fluid, due to the vicinity to the critical point, it may come to a separation of a hot gas-like layer at the wall and the cold liquid-like bulk flow. This effect is known as heat transfer deterioration (HTD) and leads to a locally disturbed heat transfer and a rising hot gas side wall temperature. This effect was also investigated during the experiments.
The structural temperature of the HARCC-segment was measured with 80 thermocouples that were placed in different axial and radial positions. These data allow a detailed survey of numerical simulation tools.
The testcase consist of a stationary load point for the cooling with hydrogen and two stationary load points for the cooling with methane, one suitable to examine the HTD-effect.
- Haemisch, J., Suslov, D., Oschwald, M. "Experimental Investigations of Heat Transfer Processes in Cooling Channels for Cryogenic Hydrogen and Methane at Supercritical Pressure", in: di Mare F., Spinelli A., Pini M. (eds) Non-Ideal Compressible Fluid Dynamics for Propulsion and Power. NICFD 2018. Lecture Notes in Mechanical Engineering. Springer, Cham. https://doi.org/10.1007/978-3-030-49626-5_1
- Haemisch, J., Suslov, D., Oschwald, M. "Experimental and Numerical Investigation of Heat Transfer Processes in Rocket Engine Cooling Channels Operated with Cryogenic Hydrogen and Methane at Supercritical Conditions", 32nd International Symposium on Space Technology and Science (ISTS) Conference, Fukui city, Japan 2019
- Haemisch, J., Suslov, D., Oschwald, M. "Experimental Study of Methane Heat Transfer Deterioration in a Subscale Combustion Chamber", Journal of Propulsion and Power, Vol. 35, No.4, 2019, https://doi.org/10.2514/1.B37394
- Haemisch, J. "Wärmeübergang von Wasserstoff und Methan in Kühlkanälen regenerativ gekühlter Schubkammern kryogener Raketentriebwerke", Dissertation, RWTH Aachen University, Germany, 2020
The flash boiling process of superheated liquid nitrogen (LN2) under high-altitude conditions was investigated with the help of a cryogenic temperature adjustment system and injection system at the test bench M3.3 at DLR Lampoldshausen.
The test fluid LN2 reaches its superheated condition by varying the injection temperature or by a low-pressure environment in the vacuum chamber of the test bench. This cylindrical chamber with an inner diameter of 300 mm provides four optical accesses to visualize the sprays and their morphology by high-speed shadowgraphy and by laser-based Phase-Doppler diagnostics (PDA).
For the present testcase, highly superheated LN2 sprays with constant injection conditions were generated. By means of PDA the local distributions of the mean droplet velocities and diameters within the flash boiling sprays were measured.
- Rees, A., Salzmann, H., Sender, J. and Oschwald, M. "Investigation of flashing LN2-jets in terms of spray morphology, droplet size and velocity distributions", 8th EUCASS Conference, Madrid, Spain, 2019.
- Rees, A., Araneo, L., Salzmann, H., Kurudzija, E., Suslov, D., Lamanna, G., Sender, J. and Oschwald, M. "Investigation of velocity and droplet size distributions of flash boiling LN2-jets with phase Doppler anemometry", 29th ILASS-Europe Conference, Paris, France, 2019.
- Gärtner, J.W., Kronenburg, A., Rees, A., Sender, J., Oschwald, M. and Lamanna, G. "Numerical and experimental analysis of flashing cryogenic nitrogen", Int. J. Multiph. Flow, 130:103360, 2020.
- Rees, A., Araneo, L., Salzmann, H., Lamanna, G., Sender, J. and Oschwald, M. "Droplet velocity and diameter distributions in flash boiling liquid nitrogen jets by means of phase Doppler diagnostics", Exp Fluids, 61, 2020.
- Rees, A., Salzmann, H., Sender, J. and Oschwald, M. "About the morphology of flash boiling liquid nitrogen sprays", At. Sprays, accepted September 2020.
- Rees, A. "Experimentelle Untersuchung der Flashverdampfung infolge der Einspritzung von kryogenem Stickstoff unter Höhenbedingungen", Dissertation, RWTH Aachen University, October 2020.