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2015-06-15
Technical Paper
2015-01-2109
Rodrigo Domingos, Daniel Silva
This paper outlines a three-dimensional computer model named AIPAC suitable for bleed-air ice protection system parametric studies in support of system design and optimization. This 3D simulation code was derived from HASPAC, which is a 2D anti-icing model developed at Wichita State University in 2010. AIPAC is based on the Finite Volumes Method and, similarly to HASPAC, combines a commercial Navier-Stokes flow solver with a Messinger model based thermodynamic analysis that applies internal and external flows heat transfer coefficients, pressure distribution, wall shear stress, etc, to compute wing leading edge skin temperatures, 3D runback flow distribution, and the location, extent and rate of icing. In addition, AIPAC was built using a transient formulation and with the capability of extruding a 3D surface mesh into a volumetric domain, so that “single-shot” ice shapes can be predicted (a more accurate multiple-step ice growth methodology is currently being developed).
2015-06-15
Technical Paper
2015-01-2100
Yongsheng Lian, Yisen Guo
This paper investigated impingement of supercooled large droplets onto smooth solid surfaces to understand the mechanism of splashing and secondary droplets formation using a novel moment of fluid (MOF) method. Previous studies have established a splashing threshold, but the effect of ambient gas in liquid droplet splashing is not fully understood. Our numerical results of water droplet splashing with relatively low velocity were consistent with experimental results: splashing occurs at high pressure but not at low pressure. Our simulation revealed that a thin film was formed after the droplet contacted the solid surface. The thin film moved at a lower speed at the contact with the solid due to viscous effect while the film moved at a higher speed away from the solid. As a result, air was trapped under the film, making the film floating on the air. When the pressure was high, the air density was high hence the aerodynamic forces by the air on the thin film.
2015-06-15
Technical Paper
2015-01-2242
Ling Zheng, Zhanpeng Fang
The design optimization of interior noise in vehicle is addressed to reduce interior noise and improve customer satisfaction in this paper. The structural-acoustic model is established and the response of sound pressure in frequency domain is predicted by using finite element method. The minimization of sound pressure inside cabins depends on body structure and the thickness for each panel. The panel participation analysis is carried out to find out the key panels as design variables and improve the efficiency of optimization computation. Response Surface Method (RSM) is proposed and utilized to optimize the vibro-acoustic properties of body structure instead of complex structural-acoustic coupling finite element model. The accuracy of the proposed RSM is evaluated and discussed. Structural-acoustic problem is approximated by a series of quadratic polynomial using RSM. Geometric optimization problem of panels is described and solved to minimize the interior noise in vehicle.
2015-06-15
Technical Paper
2015-01-2244
Ulhas Dilipraj Mohite, Niket Bhatia, Prashant Bhavsar
Noise radiated from motorcycle engine is gaining significance not only to meet regulations but also to fulfil customer demands of quiet products. In IC engines, combustion pressure is one of the major excitations which is transmitted through powertrain to the casings and radiate noise. Early identification and correction of the casing critical areas contributing to noise will lead to substantial cost and development time reduction. In this paper the approach to predict engine noise under combustion forces is presented. This Methodology is divided into three stages: 1. Multi body dynamic (MBD) Simulation to determine excitation forces 2. Vibration analysis of engine under combustion load 3. Acoustic analysis of engine to predict Sound Pressure Level (SPL). Important parts of motorcycle engine with single cylinder are considered as flexible bodies for MBD simulation.
2015-06-15
Technical Paper
2015-01-2240
Gong Cheng, David W. Herrin
The theory of patch (or panel) contribution analysis is first reviewed and then applied to a motorcycle engine on a test stand. The approach is used to predict the sound pressure in the far field and the contribution from different engine components to the sound pressure at a point. First, the engine is divided into a number of patches. The transfer function between the sound pressure in the field and the volume velocity of a patch is determined by taking advantage of vibro-acoustic reciprocity. An inexpensive monopole source is placed at the receiver point and the sound pressure is measured at the center of each patch. With the engine idling, a P-U probe was used to measure particle velocity and sound intensity simultaneously on each patch. The contribution from each patch to the target point is the multiplication of the transfer function and the volume velocity, which can be calculated from particle velocity or sound intensity. There were two target points considered.
2015-06-15
Technical Paper
2015-01-2243
Yang Liu, Pingjian Ming, Wenping Zhang, Xinyu Zhang
Turbocharger is an important part of the turbocharged diesel engine. Due to the increase of mass flow rate and pressure ratio the turbocharger, aerodynamic noise of turbocharger has become more apparent. And turbocharger noise becomes one of the major noise sources of the main engine system of the ship. In the paper, Based on Lighthill acoustic analogy theory, by using Computational fluid mechanics(CFD) and indirect boundary element method(IBEM), the aerodynamic noise prediction of marine turbocharger compressor is developed. On the basis of finite volume method, using the single stator and rotor blade passages, unsteady viscous flow in the centrifugal Compressor was simulated. The compressor’s flow characteristic was predicted and agree well with the experimental value. The flow field characteristics and frequency spectrum of the fluctuating pressure which agree well with the theoretical value were analysed.
2015-06-15
Technical Paper
2015-01-2141
Markus Widhalm
This paper focuses on the numerical simulation of the motion of regular shaped ice particles and the computation of aerodynamic forces and torques on such particles. The shape of an ice crystal may deviate considerably from a sphere and can occur as thin needles or disk-shaped configurations, referred as regular non-spherical particles, or in irregular form as flakes or agglomerates. Ice crystals can be found at the upper boundary of the troposphere in anvils of cumulonimbus clouds, where strong winds exist and an altitude, where jet aircraft cruise at transonic speed, imposing a high flow Reynolds number. As the particle size grows from a few microns into several 100's of microns a high particle Reynolds number may be expected too.
2015-06-15
Technical Paper
2015-01-2142
Colin Hatch, Roger Gent, Richard Moser
Summary Initial results from a hybrid electro-thermal electro-mechanical simulation (HETEMS) analysis tool are presented and compared to data measured during a dedicated icing trial. Temperatures and ice shed prediction data are compared with the data measured on a full size wing tested in the CIRA Icing Wind Tunnel (IWT) Additional Test Section (ATS). Background The demand for low power ice protection systems was one of the components of the EU Clean Sky initiative [1]. Under Clean Sky a research programme HETEMS looked at the development of a tool to analyse electro-thermal (ET) and electro-mechanical (EM) ice protection systems (IPS). The tool was intended to analyse independent ET and EM systems or a hybrid system using both technologies combined. The aims and scope of the tool are presented in [2]. The HETEMS software was developed around open source tools for the aerodynamic analysis [3] and mechanical failure analysis [4] in conjunction with in-house software.
2015-06-15
Technical Paper
2015-01-2151
Reinhard F.A. Puffing, Wolfgang Hassler, Andreas Tramposch, Marian Peciar
For studying ice accretion processes experimentally and establishing a valuable validation basis for ice accretion simulation models it is desirable to document experimentally generated ice shapes as accurately as possible. The generated set of data then forms the basis for aerodynamic studies, the improvement of icing test facilities, the development of design criteria, the development of ice accretion simulation tools as well as a number of further applications. In the past, various ice shape documentation methods have been established. These include photography, cross-sectional tracing, molding and casting as well as 3D-scanning. Photography is the easiest and fastest documentation method but provides little quantitative information on the ice accretion process itself. Additional quantitative information can be obtained by using multiple cameras or calibrated camera positions which, however, implicates significant additional time and cost efforts.
2015-06-15
Technical Paper
2015-01-2093
Maxime Henno
A numerical tool has been developed for predicting the unsteady behavior of the thermal wing ice protection systems (WIPS). The code was developed to account for a multi-layer composite structure. The performance predictions of a WIPS integrated into a metallic or into a composite structure can thus be achieved. The tool enables the simulation of unsteady anti-icing operations, for example, the WIPS may be activated with delay after entering into the icing conditions. In this case, ice starts to accrete on the leading edge before the WIPS heats up the skin. Another example is the ground activation of the WIPS for several seconds to check its functionality: low external cooling may cause high thermal constraints that must be estimated with accuracy to avoid adverse effects on the structure. The simulations give further opportunities compared to the current practice.
2015-06-15
Technical Paper
2015-01-2094
William B. Wright, Peter Struk, Tadas Bartkus, Gene Addy
This paper will describe two recent modifications to the GlennICE software. First, a capability for modeling ice crystals and mixed phase icing has been modified based on recent experimental data. Modifications have been made to the ice particle bouncing and erosion model. This capability has been added as part of a larger effort to model ice crystal ingestion in aircraft engines. Comparisons have been made to ice crystal ice accretions performed in the NRC Research Altitude Test Facility (RATFac). Second, modifications were made to the runback model based on data and observations from thermal scaling tests performed in the NRC Altitude Icing Tunnel. Introduction Mason[1] describes a situation where an aircraft engine can encounter rollbacks and flameouts at high altitude conditions due to ice crystal ingestion. Numerous in-fight encounters had been observed. It was hypothesized that the cause of the incidents was the ingestion of a high volume of ice crystals into the engine.
2015-06-15
Technical Paper
2015-01-2157
Mengyao Leng, Shinan Chang, Yuanyuan Zhao
Aircraft icing causes a great threaten to flight safety. With the development of anti/de-icing systems for aeronautics, some attention is paid on coating strategies for reducing the total amount of water present on the surface. By application of hydrophobic or super-hydrophobic coatings, characterized by low surface wettability, shedding of liquid from the surface can be enhanced. The motivation behind this work is to identify the way that wettability affects the motion of runback water, and establish an empirical formula of critical departure diameter. In order to contain the effect of surface wettability, it is necessary to obtain an accurate model for calculating dynamic contact angle (DCA). Instead of average static contact angle or empirical equation, the formula used in this work is derived theoretically, as a function of the capillary number, advancing and receding contact angle, and the roughness of the solid surface.
2015-06-15
Technical Paper
2015-01-2117
Miki Shimura, Makoto Yamamoto
It is well known that SLD icing is very dangerous because it is more unpredictable than general icing caused by smaller droplets. In SLD conditions, extraordinary phenomenon occurs. For example, SLD largely deforms. Vargas et al. (2010) performed the experiments about the droplet deformation. In their experiments, it was confirmed that the droplet height increases and the droplet width decreases, as the droplets approach the leading edge of an airfoil Therefore, the assumption that a droplet behaves as a sphere is no longer valid. To predict the deformation and the breakup of a droplet, several mathematical models have been proposed. For example, Ibrahim et al. (1993) proposed a model for the droplet deformation and breakup (DDB) model. However, the DDB model has not found wide acceptance. Other models exist, in which the deformation is described with the change of drag coefficient.
2015-06-15
Technical Paper
2015-01-2110
Jozef Brzeczek, Janusz Pietruszka, Robert J. Flemming, Ben C. Bernstein
The PZL M28 05 airplane is an unpressurized twin-engine high-wing strut-braced monoplane of all-metal structure, with twin vertical tails and a tricycle non-retractable landing gear. It is certified to European Aviation Safety Agency (EASA) and Federal Aviation Administration (FAA) requirements. Airplane is certified to flight into known icing conditions in accordance with 14 CFR 23.1419 requirements, including flight in the icing conditions of Appendix C of 14 CFR 25. The PZL M28 05 airplane has characteristics that include short takeoff and landing (STOL) capability, high useful load, mission versatility and easy access through the rear cargo door. Depending on the equipment installed, the airplane can be operated with up to 19 passengers, as a cargo transport, in a mixed configuration, or in patrol version. The M28 is certificated in the Part 23 commuter category. The M28 05 maximum take off gross weight is 7500 kg (16534 lb) and the maximum operational airspeed (VMO) is 192 KIAS.
2015-06-15
Technical Paper
2015-01-2119
Shinan Chang, Chao Wang, Mengyao Leng
Drop deformation and breakup is an important issue that involved in the aircraft and engine icing field especially in the case of the supercooled large droplets (SLD). In this paper, the breakup modes of SLD are discussed in detail based upon the classical theories of the drop breakup and typical icing conditions. It is found that the breakup modes of SLD are mainly vibration breakup, bag-type breakup, multimode breakup and shear breakup. As the vibration breakup mode is rare, focuses are put on the bag-type breakup, multimode breakup and shear breakup. Because the drop Weber number is increasing gradually when the drops are approaching the leading edge of the airfoil and the drop Weber number differs in different locations of the airfoil surface, two or three breakup modes may appear simultaneously in a given environmental condition.
2015-06-15
Technical Paper
2015-01-2121
Yong Chen, Liang Fu
In helicopter, the icing rotor blades will decrease the effectiveness of the helicopter and endanger the lives of the pilots. The asymmetrical ice break-up and shedding could also lead to severe vibrations of the rotor blade. Ice break-up from the main rotor may strike the fuselage and tail rotor, even worse, find its way into the engine, which may cause serious aircraft accidents. An understanding of the mechanisms responsible for ice shedding process is necessary in order to optimize the helicopter rotor blade design and de-icing system to avoid hazardous ice shedding. In previous study, the ice shedding criteria was established by comparing the centrifugal force and the adhesion force. In most cases, part of the ice will shed before the centrifugal force equals to the adhesion force, because the adhesion stress between the ice and the blade is not uniform.
2015-06-15
Technical Paper
2015-01-2103
Christian Bartels, Julien Cliquet, Carlos Bautista
Icing is a phenomenon observed on aircraft airframes while flying through clouds of supercooled droplets. The phenomenon only occurs for ambient air temperatures below the freezing point. The droplets impinge on the aircraft surfaces and freeze, leading to ice accretion. The resulting change in aircraft geometry and surface roughness can modify the aircraft’s aerodynamic characteristics (lift loss, drag increase), it may affect air data probe measurements, and can even damage the engines by ice ingestion. In order to comply with certification regulations, airframers have to demonstrate safe operation of their aircraft in icing conditions. However, due to associated cost and time, it is prohibitive to cover the whole icing envelope by flight-testing or icing-tunnel testing. Therefore, aircraft manufacturers have developed, with support from research institutes, numerical prediction methods and tools to cover their prediction needs.
2015-06-15
Technical Paper
2015-01-2082
Andreas Tramposch, Wolfgang Hassler, Reinhard F.A. Puffing
Certain operating modes of the Environmental Control System (ECS) of passenger aircraft are accompanied with significant ice particle accretion in a number of pivotal parts of the system. Icing conditions particularly prevail downstream of the air conditioning packs and, as a consequence, ice particle accretion takes place in the Pack Discharge Duct (PDD) and in the mixing manifold. For a better understanding of these icing processes, numerical simulations using a multiphase model based on a coupled Eulerian-Lagrangian transport model in a generic PDD were performed. The obstruction of the PDD due to ice growth and the resulting change of the flow geometry were treated by deforming the computational mesh during the CFD simulations. In addition to the numerical investigations, a generic and transparent PDD was studied experimentally under several operating conditions in FH JOANNEUM’s icing wind tunnel.
2015-06-15
Technical Paper
2015-01-2161
Kazem Hasanzadeh, Dorian Pena, Yannick Hoarau, Eric Laurendeau
The paper will present the framework of fully automated two/three dimensional ice accretion simulation package NSMB3D-ICE, with emphasis on the remeshing step. The NSMB3D-ICE Navier-Stokes code, coupled to an Eulerian droplet module and iterative Messinger thermodynamic model, can perform multi time-steps ice accretion simulations via an automated multi-block elliptic/parabolic grid generation code (NSGRID3D). Attention is paid to the efficiency and robustness of the numerical procedure especially for complex 3D glaze ice simulation. The new automated multi time-step icing code NSMB3D-ICE/NSGRID3D is validated and verified using several icing case studies such as the GLC305-3D rime and glaze ice cases. The Navier-Stokes flow solver NSMB3D is a finite volume three-dimensional multi-block Euler/Navier-Stokes flow solver developed by J. Vos et al. [1-3].
2015-06-15
Technical Paper
2015-01-2135
Martin Schulz, Michael Sinapius
A designer of a new mechanical ice protection system for airplanes needs to know how much and in which way he has to deform the surface to break off the ice. The ice adhesion strength is often used as design value. To measure the adhesive strength several methods have been published. This paper presents a review about those methods and discusses the way the adhesion strength is derived. Finite Element Method is used to give a good insight into the stress state at failure for different load cases. The implication of these illustrations is that equations which use only ultimate force and total interfacial area to calculate adhesion strength miss the local stress state at the crack tip and the complex process of crack growing. Hence the derived adhesion strength may not be comparable with others, because they depend in fact on neglected parameters like specimen size, substrate thickness and stiffness.
2015-06-15
Technical Paper
2015-01-2139
E.J. Grift, E. Norde, E.T.A. Van der Weide, H.W.M. Hoeijmakers
In this study the characteristics of ice crystals on their trajectory in a single stage of a turbofan engine compressor will be determined. The particle trajectories are calculated with a Lagrangian method employing a classical fourth-order Runge-Kutta time integration scheme. The air flow field is provided as input and is a steady flow field solution governed by the Euler equations. The single compressor stage is represented using a cascaded grid. The grid consists of three parts of which the first and the last part are stator parts and the centre part is a rotor. This grid is linearly cascaded, i.e. repeated infinitely above and below the shown grid, to represent the other blades of this stator-rotor-stator stage. The rotor movement is accomplished by prescribing a relative velocity of the rotor part relative to the stator parts and the interface between rotor and stator is modelled by using a mixing plane assumption allowing a steady-state analysis.
2015-06-15
Technical Paper
2015-01-2140
Emiliano Iuliano
The presence of ice crystals in deep convective clouds has become a major threat for aviation safety. As recently highlighted, once inside the engine core, ice crystals encounter a high temperature environment, so that they can either melt by convection with the warm environment or melt upon impact onto hot static components of the low-pressure components. As a consequence, a liquid film may form which, in turn, is able to capture further ice crystals by sticking mechanism. This scenario results in a significant decrease of the local surface temperature and, hence, promotes the accretion of ice. Therefore, it is clear that icing simulation capabilities have to be updated in order to be able to predict such phenomena. The paper proposes an extension of CIRA icing tools to deal with ice crystals along with supercooled water droplets.
2015-06-15
Technical Paper
2015-01-2083
Daniel Silva, Thais Bortholin, J Allan Lyrio, Luis Santos
An important issue regarding landing performance is the reference speed which determines the approved fields lengths in which a landing can take place. The critical scenario is the accumulation of ice during the holding phase followed by descent, approach and landing. The effect of icing in the landing configuration, with the high-lift devices deployed, is relevant and should be anticipated during the early design phases by simulation. Due to the complex behaviour of the flowfield, 3D CFD methods has been used but that leads to a high computational cost which might be too intensive for the preliminary design phases . The purpose of this paper is to describe a lower cost procedure combining CFD and Quasi-3D modified Weissinger´s Method [3] which provides an accurate assessment of these effects to 5% margin in ∆CL , confirmed by wind tunnel testing.
2015-06-15
Technical Paper
2015-01-2088
Richard E. Kreeger, Lakshmi Sankar, Robert Narducci, Robert Kunz
The formation of ice over lifting surfaces can affect aerodynamic performance. In the case of helicopters, this loss in lift and the increase in sectional drag forces will have a dramatic effect on vehicle performance. The ability to predict ice accumulation and the resulting degradation in rotor performance is essential to determine the limitations of rotorcraft in icing encounters. The consequences of underestimating performance degradation can be serious and so it is important to produce accurate predictions, particularly for severe icing conditions. The simulation of rotorcraft ice accretion is a challenging multidisciplinary problem that until recently has lagged in development over its counterparts in the fixed wing community. But now, several approaches for the robust coupling of a computational fluid dynamics code, a rotorcraft structural dynamics code and an ice accretion code have been demonstrated.
2015-06-15
Technical Paper
2015-01-2138
E. Iuliano, E. Montreuil, E. Norde, E.T.A. Van der Weide, H.W.M. Hoeijmakers
In this study a comparison will be made between three Eulerian-based solvers that predict the ice crystal trajectories and impingement on a NACA-0012 airfoil. The codes are being developed within CIRA, ONERA and University of Twente, and are improvements to their in-house Eulerian codes called Imp2D/3D, CEDRE/Spiree and MooseMBIce, respectively. This cooperation between CIRA, ONERA and University of Twente was initiated in the framework of European funded project HAIC (High Altitude Ice Crystals), a large-scale integrated project which aims at enhancing aircraft safety when flying in mixed phase and glaciated icing conditions. The numerical codes differ by the general architecture and implementation of the cloud particle size distribution. Imp2D/3D and MooseMBIce are based on a finite volume approach for multi-block structured grid. CEDRE/Spiree also employs a finite volume approach but handles generalized unstructured grids.
2015-06-15
Technical Paper
2015-01-2115
Antonio Criscione, Suad Jakirlic, Zeljko Tukovic, Ilia Roisman, Cameron Tropea
Atmospheric icing occurs when supercooled large drops (SLD) of water come in contact with the surface of exposed structures. Excessive accumulation on structures and equipment is well known for causing serious problems in cold-climate regions which lead to material damage and high costs in various sectors of the economy. Hereby, SLD impact with the exposed structure results consequently in an ice layer growth covering the surface of the substrate. The present study enables, among other things, modeling of both stages of the solidification process of a supercooled large water drop on a cold substrate - the first rapid, recalescent stage and the second slower, quasi-isothermal stage. The different mechanisms underlying both freezing stages can be explained as follows: in the first stage the initial planar solidification front becomes morphologically unstable due to a high degree of supercooling. Small bumps/instabilities evolving at the interface propagate further into the liquid.
2015-06-15
Technical Paper
2015-01-2155
Tadas P. Bartkus, Peter Struk, Jen-Ching Tsao
This paper describes a numerical model that simulates the thermal interaction between ice particles, water droplets, and the flowing air applicable during icing wind tunnel tests where there is significant phase-change of the cloud. The model is compared to measurements taken during wind tunnel tests simulating ice-crystal and mixed-phase icing that relate to ice accretions within turbofan engines. This model, written in MATLAB, is based on fundamental conservation laws and empirical correlations. Due to numerous power-loss events in aircraft engines, potential ice accretion within the engine due to the ingestion of ice crystals is being investigated. To better understand this phenomenon and determining the physical mechanism of engine ice accretion, fundamental tests have been collaboratively conducted by NASA Glenn Research Center and the National Research Council of Canada (NRC).
2015-06-15
Technical Paper
2015-01-2131
Colin Bidwell, David Rigby
A flow and ice particle trajectory analysis was performed for the booster of the Honeywell ALF502 engine. The analysis focused on two closely related conditions one of which produced an icing event and another which did not during testing of the ALF502 engine in the Propulsion Systems Lab (PSL) at NASA Glenn Research Center. The flow analysis was generated using the NASA Glenn GlennHT flow solver and the particle analysis was generated using the NASA Glenn LEWICE3D v3.61 ice accretion software. The inflow conditions for the two conditions were similar with the main difference being that the condition that produced the icing event was 6.8 K colder than the non-icing event case. The particle analysis, which considered sublimation, evaporation and phase change, was generated for a 5 micron ice particle with a sticky impact model and for a 24 micron, 7 bin ice particle distribution with an SLD splash model used to simulate ice particle breakup.
2015-06-15
Technical Paper
2015-01-2122
Cameron Butler, Eric Loth
INTRODUCTION To support a collaborative research project aimed at studying icing on large-scale, swept wings, unsteady simulations were performed on test articles with and without icing in NASA Glenn’s Icing Research Tunnel (IRT). The models being tested are all swept hybrid models designed to have the same leading-edge geometry as a 65% scaled version of the Common Research Model (CRM). Three models were designed as hybrid airfoils where the leading edge geometry and flow field matched that of the CRM, but the rest of the airfoil was reduced substantially in length to accommodate the tunnel cross-section. This hybrid design allows for the largest leading-edge which avoids complex issues associated with geometric scaling in icing conditions. To investigate the effect of sweep along the wing, three different test models are investigated to represent different spanwise locations along the CRM, from inboard, mid-span and outboard.
2015-06-15
Technical Paper
2015-01-2084
Benedikt König, Ehab Fares, Andy P. Broeren
A new laser-scanning method was applied to capture the three-dimensional ice shapes created during ice-accretion test on a NACA 23012 airfoil conducted in the NASA Icing Research Tunnel. This facilitated the creation of high-fidelity digital surface representations of complex ice-shapes. Those digital shapes cannot only be used to create rapid-prototyping models for experimental simulations, but also serve as input for computational fluid dynamics (CFD) simulations. In the past, numerical simulations of iced airfoils and wings were typically based on simplified. But, independent of the complexity of the ice shape, current numerical methods often struggle with the complicated, highly unsteady separated flows occurring under iced conditions. In this work we present simulations based on the Lattice-Boltzmann methodology (LBM) and investigate it’s capability to simulate the flow around three-dimensional laser-scanned ice shapes.
Viewing 1 to 30 of 30067