D. H. Lieberman

Bio: D. H. Lieberman is an academic researcher from Exponent. The author has contributed to research in topics: Deflagration to detonation transition & Combustion. The author has an hindex of 1, co-authored 1 publications receiving 19 citations. Previous affiliations of D. H. Lieberman include California Institute of Technology.

Detonation interaction with a diffuse interface and subsequent chemical reaction

Abstract: We have investigated the interaction of a detonation with an interface separating a combustible from an oxidizing mixture. The ethylene-oxygen combustible mixture had a fuel-rich composition to promote secondary combustion with the oxidizer in the turbulent mixing zone that resulted from the interaction. Diffuse interfaces were created by the formation of a gravity current using a sliding valve that initially separated the test gas and combustible mixture. Opening the valve allowed a gravity current to develop before the detonation was initiated. By varying the delay between opening the valve and initiating the detonation it was possible to achieve a wide range of interface conditions. The interface orientation and thickness with respect to the detonation wave have a profound effect on the outcome of the interaction. Diffuse interfaces result in curved detonation waves with a transmitted shock and following turbulent mixing zone. The impulse was measured to quantify the degree of secondary combustion, which accounted for 1–5% of the total impulse. A model was developed that estimated the volume expansion of a fluid element due to combustion in the turbulent mixing zone and predicted the resulting impulse increment.

Detonation propagation in hydrogen-air mixtures with transverse concentration gradients

Abstract: The influence of transverse concentration gradients on detonation propagation in $$\hbox {H}_2$$ –air mixtures is investigated experimentally in a wide parameter range. Detonation fronts are characterized by means of high-speed shadowgraphy, OH* imaging, pressure measurements, and soot foils. Steep concentration gradients at low average $$\hbox {H}_2$$ concentrations lead to single-headed detonations. A maximum velocity deficit compared to the Chapman–Jouguet velocity of 9 % is observed. Significant amounts of mixture seem to be consumed by turbulent deflagration behind the leading detonation. Wall pressure measurements show high local pressure peaks due to strong transverse waves caused by the concentration gradients. Higher average $$\hbox {H}_2$$ concentrations or weaker gradients allow for multi-headed detonation propagation.

Gas-phase detonation propagation in mixture composition gradients.

Abstract: The propagation of detonations through several fuelair mixtures with spatially varying fuel concentrations is examined numerically. The detonations propagate through two-dimensional channels, insid...

Role of transversal concentration gradient in detonation propagation

Abstract: The role of a transversal concentration gradient in detonation propagation in a two-dimensional channel filled with an bump and thus the unreacted pocket behind the front, while the transverse wave causes mixing and burning of the residue fuel downstream. Nevertheless, for the steepened concentration gradient, a transverse detonation is present and consumes the fuel in the compressed and preheated zone by the leading shock; consequently, the detonation velocity deficit is not increased significantly for detonation with the single-head propagation mode close to the limit.

Deflagration-to-Detonation Transition and Detonation Propagation in H2-Air Mixtures with Transverse Concentration Gradients

Abstract: Explosion of H2-air mixtures portrays a major hazard in nuclear reactors during severe loss-of-coolant accidents. Spatial gradients in H2 concentration prevail in real-world scenarios. Mixture inhomogeneity can lead to significantly stronger explosions as compared to homogeneous mixtures. The present work identifies and quantifies the underlying physical mechanisms.

Deflagrations, Detonations, and the Deflagration-to-Detonation Transition in Methane-Air Mixtures

Abstract: : Explosions in mixtures of natural gas (NG) and air have been of intense practical concern for coal mines for many years. Potentially explosive mixtures of NG and air can accumulate in the active ventilated areas or in unventilated sealed areas of these mines. If an ignition source, such as a simple spark, ignites the NG-air mixture and creates a flame, the initially slow-moving flame can become turbulent, accelerate rapidly, develop extremely intense pressure waves, and potentially generate enormous stress on coal mine seals. In this work, we attempt to answer the question: Given a large enough volume of flammable mixture of NG and air, can a weak spark ignition develop into a detonation? Large-scale numerical simulations, in conjunction with experimental work conducted at the National Institute for Occupational Safety and Health?s Gas Explosion Test Facility, were performed to address four specific problems: flame acceleration and deflagration-to-detonation transition (DDT) in obstructed channels containing a stoichiometric methane-air mixture, flame acceleration and DDT in fuel-lean and fuel-rich mixtures, effects of spatially varying fuel concentrations on detonations, and stochastic effects on flame acceleration and DDT.