Uncertainty Quantification Approach on Numerical Simulation for Supersonic Jets Performance

Abstract

One of the main issues addressed in any engineering design problem is to predict the performance of the component or system as accurately and realistically as possible, taking into account the variability of operating conditions or the uncertainty on input data (boundary conditions or geometry tolerance). In this paper, the propagation of uncertainty on boundary conditions through a numerical model of supersonic nozzle is investigated. The evaluation of the statistics of the problem response functions is performed following ‘Surrogate-Based Uncertainty Quantification’. The approach involves: (a) the generation of a response surface starting from a DoE in order to approximate the convergent–divergent ‘physical’ model (expensive to simulate), (b) the application of the UQ technique based on the LHS to the meta-model. Probability Density Functions are introduced for the inlet boundary conditions in order to quantify their effects on the output nozzle performance. The physical problem considered is very relevant for the experimental tests on the UQ approach because of its high non-linearity. A small perturbation to the input data can drive the solution to a completely different output condition. The CFD simulations and the Uncertainty Quantification were performed by coupling the open source Dakota platform with the ANSYS Fluent® CFD commercial software: the process is automated through scripting. The procedure adopted in this work demonstrate the applicability of advanced simulation techniques (such as UQ analysis) to industrial technical problems. Moreover, the analysis highlights the practical use of the uncertainty quantification techniques in predicting the performance of a nozzle design affected by off-design conditions with fluid-dynamic complexity due to strong nonlinearity.

Uncertainty Quantification Analysis of Exhaust Gas Plume in a Crosswind

“…A more representative analysis is performed with the introduction of a normal probability density function (pdf) for the input variables, which can more realistically simulate the uncertainty related to the gas velocity found at the exit of an exhaust funnel. An example is shown in Figure 16: it has a mean value centered in the range of (20 [m/s]) with a standard deviation of 2 [m/s], which is the estimated uncertainty of the variable, selected from the experience of previous works [37][38][39]; the aim is to verify the effect of a small deviation from the mean. These results confirm the hypothesis that a relatively small change in the vf can cause a significant change in the QoI and, consequently, in the plume evolution.…”

“…Computational fluid dynamics (CFD) is one of the latest disciplines where UQ techniques have been exploited with increasing relevance. The recent developments in response surface methodology (RSM), which is normally very effective for optimization in design processes [35,36], have also led the way for the application of UQ to this field [37][38][39]. Several UQ methods have been applied in stochastic fluid dynamics problems, including Monte Carlo (MC-whose accuracy is affected by the sampling point number), perturbation method, moment method and surrogated models.…”

The Use of Uncertainty Quantification and Numerical Optimization to Support the Design and Operation Management of Air-Staging Gas Recirculation Strategies in Glass Furnaces

“…The purpose is to evaluate how uncertainty propagates in the physical system (or through simulations) and how it affects the output variables. A validated approach has been adopted by following previous work [45]. In this case, the two mass flow rates of the injectors have been considered as probabilistic input parameters with their pdfs and their impact on the output variable (bypass mass flow rate) has been analyzed.…”

Study on the Flow State of Circulating Cooling Water for the Industrial Heat Exchange Tube in the Electromagnetic Anti-Fouling Process

“…The effect of electromagnetic anti-fouling technology on fouling mitigation in a heat exchanger has gained wide attention . There are sufficient works on chemical and physical methods for fouling removal and inhibition, though the mechanism and effectiveness of electromagnetic water treatment technology have not been fully studied . This paper conducts numerical simulation research on the flow states of circulating cooling water, as well as experimental analysis for the characteristics of fouling resistance in the electromagnetic anti-fouling process, to further draw conclusions regarding the pace for fouling formation and adhesion of fouling on the surface of heat exchange equipment.…”